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Luminance is an essential quality of a TFT-LCD display. Manufacturers have attempted to improve the soft-to-hard lamination stage to enhance the luminance of their TFT-LCD displays. In addition, many customers have complained about the insufficient luminance of the TFT-LCD displays of the case company. While product engineers have kept tuning the control factors in the soft-to-hard lamination stage through the trial and error method, the improvement of the luminance was not good enough. This study aims to assist the product engineers to fine-tune the settings of the control factors using a new method composed of the Taguchi method, a neural network, and a genetic algorithm. The confirmation experiments showed that the proposed method had increased the average luminance of the TFT-LCD displays from 17.03 to 25.15, which was higher than the required luminance value of 25. As a result, the number of complaints on the TFT-LCD displays had been significantly reduced.

Orientadores: Éder Lima de Albuquerque, Paulo Sollero Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica Resumo: Este trabalho apresenta um método de elementos de contorno para a análise de estabilidade de placas de materiais compósitos laminados. A formulação do método proposto não necessita de discretização do domínio, nem de soluções particulares para a solução do problema. Isto torna a formulação proposta diferente das formulações de elementos de contorno existentes, aplicadas à análise de estabilidade estrutural. O método é aplicado a um problema importante em engenharia computacional, que é a estabilidade de placas de materiais isotrópicos e de compósitos laminados. O desempenho é avaliado através de comparação com os resultados de elementos finitos e resultados analíticos, mostrando boa concordância com os mesmos. No entanto, a vantagem em relação ao método dos elementos finitos, especificamente, em análise de estabilidade de placas de materiais compósito laminados, é que se torna um problema de autovalor com um número reduzido de graus de liberdade, uma vez que somente o contorno e poucos pontos internos são necessários na discretização do problema Abstract: This work presents a boundary element method to the analysis of buckling plates. Neither domain discretization, nor particular solutions are necessary in the proposed formulation. This becomes the proposed formulation different from the existent boundary element formulations applied to structural stability analysis. The method is applied to an important problem in computational engineering that is the stability of perforated and non perforated plates of composite laminate materials. The performance is assessed through comparison with finite element results. The proposed formulation agrees quite well with finite element. However, the stability analysis is a much smaller eigenvalue problem if boundary elements are used instead of finite elements, provided that only the boundary and fewer internal points are necessary in the discretization Doutorado Mecânica dos Sólidos e Projeto Mecânico Doutor em Engenharia Mecânica

Orientadores: Eder Lima de Albuquerque, Paulo Sollero Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica Resumo: Este trabalho apresenta uma formulação dinâmica do método dos elementos de contorno para o cálculo de tensões e critério de falhas de placas finas anisotrópicas. As formulações utilizam soluções fundamentais da elasto-estática e os termos de inércia são tratados como forças de corpo. As integrais de domínio provenientes de forcas de corpo são transformadas em integrais de contorno usando o método da integração radial (RIM). No RIM, a função de aproximação "thin plate spline"de placas finas e usada na aproximação das forças de corpo. São implementados formulações para análise transiente de placas finas. A integração no tempo é realizada usando o método de Houbolt. Uma equação integral para a segunda derivada de deslocamento é desenvolvida e todas as derivadas da solução fundamental são calculadas analiticamente. Apenas o contorno é discretizado. Os resultados numéricos apresentaram boa concordância com os resultados disponíveis na literatura e também com resultados do método dos elementos finitos Abstract: This work presents a dynamic formulation of the boundary element method for stress and failure criterion analyses of anisotropic thin plates. Formulations use elastostatic fundamental solutions and inertia terms are treated as body forces. Domain integrals that come from body forces are transformed into boundary integrals using the radial integration method (RIM). In the RIM, the augmented thin plate spline is used as the aproximation function. A formulation for transient analysis is implemented. The time integration is carried out using the Houbolt method. Integral equations for the second derivatives of deflection are developed and all derivatives of fundamental solutions are computed analitically. Only the boundary is discretized in the formulation. Numerical results show good agreement with results available in literature as well as finite element results Mestrado Mecânica dos Sólidos e Projeto Mecânico Mestre em Engenharia Mecânica

Turbinas eólicas são máquinas capazes de converter energia cinética do vento em eletricidade. As pás da turbina são responsáveis por converter as forças aerodinâmicas em torque para o gerador. Na maioria dos casos, as pás são fabricadas com materiais compósitos e sua rigidez e comportamento têm influência direta no desempenho da turbina, e, por sua vez, o material e sequência de laminação influenciam na rigidez da pá. Tirando proveito do acoplamento flexão-torção proporcionado pela sequência de laminação dos materiais compósitos, é possível produzir um controle passivo do ângulo de arfagem das pás de geradores eólicos de pequeno porte. Esse controle passivo tem por objetivo melhorar o rendimento das pás para velocidades de vento superiores à que a velocidade nominal de projeto. Dentro deste contexto, o presente trabalho tem como objetivo obter a melhor configuração de empilhamento para o projeto de uma pá de turbina eólica de material compósito laminado utilizando uma técnica de otimização baseada em metamodelagem. Para isso, utiliza-se o método dos elementos finitos para modelar o comportamento mecânico de uma pá. O modelo é parametrizado de forma a simular diferentes configurações de laminados e avaliar o comportamento da pá com diferentes velocidades de vento. A partir de resultados de simulações do modelo de elementos finitos é construído um metamodelo, utilizando funções de base radial. Adotam-se como variáveis de entrada as orientações das lâminas do material compósito e, como saída, o coeficiente de potência da turbina eólica. Em posse do metamodelo, realizase um processo de otimização para encontrar a sequência de laminação que fornece o melhor coeficiente de potência. Essa sequência é comparada com as demais configurações de laminado, assim como as respostas obtidas através do metamodelo são verificadas com as respostas do modelo de elementos finitos. Os resultados encontrados demonstram que a metodologia de otimização utilizando metamodelos é eficiente, além disso, o controle passivo do ângulo de arfagem de pás de geradores eólicos pode ser empregado gerando ganho de rendimento da turbina, usando para isso o acoplamento flexão-torção dos materiais compósitos. Wind turbines are machines capable of transforming wind kinetic energy into electricity. The turbine blades are responsible for converting aerodynamic forces into torque for the generator. In most cases, blades are made of composite materials and their stiffness and behavior affect the turbine performance, on the other hand, the material and layup orientation influence the blade stiffness. By taking advantage of the bendtwist coupling that is offered by the layup sequence of composite materials, it is possible to produce a passive control of the pitch angle in small size wind turbines. The passive control aims to improve the blade performance for higher wind speeds than the nominal design speed. Within this context, this research aims to obtain the best layup sequence of a wind turbine blade made of laminated composite material using metamodeling based optimization. For this, the finite element method is used to model the mechanical behavior of the wind turbine blade. The model is parameterized in order to simulate several layup configurations and to evaluate the behavior of the blade undergoing different wind speeds. From the simulation responses of the finite element model, a surrogate model is generated, using radial basis functions. Ply orientations are adopted as input variables, and the power coefficient of the wind turbine as output. In possession of the metamodel, an optimization process is carried out to find the layup sequence that offers the highest power coefficient. The optimized layup sequence is compared with other layup configurations, as well as the surrogate model responses with the finite element model itself. The results demonstrate that the optimization methodology using metamodels is efficient, moreover, the passive control of the pitch angle of wind turbine blades can be applied and generates a better performance for the turbine, using for that the bend-twist coupling of composite materials.

This work is made to ascertain the effects of mineral fillers, namely calcium carbonate and talc, on the morphology and properties of multilayer polypropylene (PP)/high-density polyethylene (HDPE) porous membranes. Multilayer membranes were prepared using the three-stage Melt-Extrusion, Annealing and Uniaxial Stretching (MEAUS) process. The orientation of PP&rsquo, s crystalline phase was affected by both the flow-induced crystallization and the heterogeneous nucleation promoted by the fillers. A synergistic effect was observed in the filled samples due to the generation of pores after the stretching-induced lamellae separation and the debonding of mineral fillers from the polymeric matrix. The fillers increased the porous surface, leading to an increase of permeance to air, being this effect more marked at higher filler contents. Talc showed a higher efficiency to create porous surfaces when compared to calcium carbonate. The thermal stability of the membranes increased with filler addition, as well as their stiffness and strength.

Laminated glass beams without metallic or polymeric reinforcements generally lack post-breakage strength and ductility. This paper aims to perform a comparative study by testing five different fully transparent laminated glass beam designs in order to see how parameters such as the number and thickness of glass sheets (3 x 10 mm or 5 x 6 mm), the interlayer material (PVB Clear or SentryGlas), and the thermal treatment of glass (annealed or heat-strengthened) affect the pre-breakage performance and post-breakage safety. A buckling analysis is also performed using a numerical model with ABAQUS CAE. The study includes a comparison between the results of different experimental mechanical tests on laminated glass beams, including the tests presented in this paper, as well as other tests found in the literature. All designs presented a linear elastic behaviour until initial breakage. The interlayer material mainly affected the crack shape of laminated glass beams. Beams with five sheets of annealed glass had a more progressive breakage, and therefore a safer behaviour, than beams with three sheets of annealed or heat-strengthened glass. The work was partially funded by CRISTEC with CDTI funds (IDI-20160588). The authors at the University of Lleida would like to thank the Catalan Government for the quality accreditation given to their research group GREiA (2017 SGR 1537). GREiA is certified agent TECNIO in the category of technology developers from the Government of Catalonia. This work is partially supported by ICREA under the ICREA Academia programme. The financing support given by the Spanish Ministry of Economy and Competitiveness through the project BIA2014-53774-R is gratefully appreciated. Xavier Centelles would like to thank University of Lleida for his research fellowship and to the University of Oviedo for hosting his secondment during 2019. Funding Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature.

Laminated epoxy dielectric graded material is a commonly used insulating material with broad application prospects in power equipment. The interlaminar interfaces of laminated epoxy dielectric material between different layers form during its lamination process, and these interfaces are the crucial characteristic structures determining the mechanical and dielectric properties of laminated materials. Therefore, in order to gain a thorough understanding of physic properties behind a certain structural motif, it is necessary to study how these interfacial structures influence the mechanical and dielectric performances of graded materials. In this study, double-layered epoxy resin samples with an interlaminar interface are prepared to study their mechanical and dielectric strength. More importantly, the formation mechanism of the interface, as well as its influence on the mechanical and dielectric strength of this laminated material, is discussed. We found that a cross-linking reaction may take place between epoxy resins at the interlaminar interface, and the degree of cross-linking at the interface should be less than that in the bulk. The mechanical strength of the interlaminar interface is weaker than that of the bulk, and it is reduced by less than 40%. Moreover, the interlaminar interface is inclined to trap carriers, which improves the breakdown strength and arc ablation resistance of the laminated material. Our study of interlaminar interface properties could help in designing epoxy dielectric graded materials with better mechanical and dielectric properties.

The quest for impact damage tolerant laminates by tailoring stacking sequences has led to nonconventional laminates whose ply sequences are not limited to 0, ±45 and 90°. Departing from the hypothesis that compression after impact (CAI) strength is impaired by the presence of delaminations, a ply sequence was defined by selecting the mismatch angles between plies so as to maintain a central sublaminate with no, or small, delaminations. An experimental test campaign was devoted to validate this hypothesis. To that purpose, baseline and blocked-ply laminates were included in the study. Specimens were tested under low velocity impact followed by compression according to ASTM standards. Delaminations were identified with Ultrasonic C-Scan. The results show delamination locations being successfully predetermined by controlling the mismatch angle, as well as the ensuing improvement in compressive strength retention after impact The authors acknowledge the financial support of the Spanish Ministerio de Ciencia e Innovación under the project MAT2015-69491-C3-1-R (MINECO/FEDER, UE)

Bu çalışmada, günden güne pazar payı artan ahşap mühendislik ürünlerinden CLT'nin Türkiye'deki yerli ağaç türlerinden üretilmesi ve en uygun üretim şartlarının ortayakoyulacağı üretim parametrelerinin belirlenmesi amaçlanmıştır.Ağaç malzeme olarak Sarıçam (Pinus sylvestris L.), Doğu Ladini (Picea orientalisL.) ve Göknar (Abies nordmanniana), 2 farklı kereste kalınlığı ve iki farklı tutkallama şekliuygulanarak CLT paneller üretilmiştir. CLT üretiminde kullanılan kerestelerin eğilmedirenci TS 2474, elastikiyet modülü testleri TS 2478, liflere paralel basınç direnci testleriTS 2595 ve pürüzlülük ölçümleri DIN 4768 standartlarına göre yürütülmüştür. ÜretilenCLT panellere uygulanan eğilme direnci ve eğilmede elastikiyet modülü testleri,ANSI/APA PRG 320 standardına göre yürütülmüştür. Çalışma kapsamında CLT duvaranalizi testi ASTM E 72 standardına göre doğrusal yük altında gerçekleştirilmiştir. Ayrıca,yapay sinir ağları (YSA) modeli kurularak, çalışma kapsamındaki perde duvar gruplarınınoptimizasyonu yapılmıştır. Sonuç olarak, Karadeniz Bölgesi yerli ağaç türlerinden CLTüretilebileceği ve önemli bir katma değer sağlayacak performansa sahip olduğugörülmüştür. Yapılan mekanik testler neticesinde yerli türlerden üretilen CLT ürünlerinAvrupa standartlarına uygun kalitede olduğu tespit edilmiştir. In this study, the engineered wood products market share increasing from day to dayCLT's the production of native tree species in Turkey and aimed to determine theproduction parameters to outline the optimal production conditions.As wood material, Scots Pine (Pinus sylvestris L.), Eastern Spruce (Picea orientalisL.) and Eastern Black Sea Fir (Abies nordmanniana), 2 different timber thickness and twodifferent gluing forms are applied and CLT panels are produced. The bending strength ofthe timber used in the production of CLT was TS 2474, the modulus of elasticity tests TS2478, the pressure resistance tests in parallel with the fibers TS 2595 and the roughnessmeasurements were conducted according to DIN 4768 standards. Bending strength andmodulus of elasticity tests applied to CLT panels were conducted according to ANSI /APA PRG 320 standard. CLT wall analysis test was performed under linear load accordingto ASTM E 72 standard. In addition, artificial neural networks (ANN) model has beenestablished and the CLT wall groups in the scope of the study have been optimized. As aresult, it is seen that CLT can be produced from indigenous tree species in the Black SeaRegion and has a performance that will provide a significant added value. As a result of themechanical tests, CLT products produced from domestic species were found to be incompliance with European standards. 122

Amaç: Bukkal yüzeyde hazırlanan lamina vener destekli tam seramik RBFDP'ninklinik başarısı, yapılan araştırmaların yetersizliğinden dolayı tam olarakbilinmemektedir. Bu çalışmanın amacı, alt kesici dişler üzerinde farklı konnektörkalınlığına sahip lamina vener destekli köprülerde könnektör kalınlığının kırılmadirenci üzerindeki etkisini değerlendirmektir.Materyal ve Metot: Alt çene periodontal ligament yapısına sahip, alt sağ orta ve solyan kesici dişi içeren üç boyutlu sonlu elemanlar analiz modeli hazırlandı. Dahasonra, farklı konnektör kalınlığına sahip (1 mm kannektör kalınlığı grubu ve 2 mmkonnektör kalınlığı grubu) üç üyeli lamina vener destekli köprüden oluşan 2 grupoluşturuldu. Yapıştırıcı siman kalınlığı her iki grupta da aynı hazırlandı. Her ikigruba da ısırma kuvvetlerini taklit edecek 100 N'luk yük 3 üyeli köprülerin gövdeleriüzerine bukkal yüzden 45 derecelik açı ile uygulandı. Kırılma kuvvetlerikarşılaştırıldı.Bulgular: Konnektör kalınlığı 2 mm olan gruptaki gerilim kuvvetleri, 1 mmkonektör kalınlığına sahip gruba göre daha düşük değerler elde edildi.Sonuç: Bu çalışmanın klinik sonucuna göre, 2 mm konnektör kalınlığına sahip üçüyeli RBFDP'lerin, 1 mm konektör kalınlığına sahip olan RBFDP'ler den dahagüvenilir olduğu sunucuna varılmıştır. Bukkal yüzde hazırlanan lamina destekliköprüler hem estetik hem de dayanıklılık açısından tercih edilebilirler.Anahtar Kelimeler: (Lamina vener, Konnektör, Sonlu Elemanlar Analizi) Aim: Laminate retained all-ceramic RBFDP's clinical success is unknown due to lack of insufficient studies about them. The purpose of this study is to evaluate the Effect of the connector thickness on fracture resistance in laminate veneers retained bridges in the lower central incisor region via finite element method.Material and Method: A three-dimensional finite element analysis model will be developed including mandible, prepared lower right central and left lateral incisor with periodontal ligament structures. Then a 2 groups of a three unit buccally retained laminate veneer bridge was virtually constructed with different thickness of connector a (1mm connector thickness group and 2mm connector thickness group), also a uniform thickness was designed for cement. A load of 100 N applied to the buccal surface at 45 degree, 2mm below the incisal edge of the pontic on both 2 groups three unit to stimulate biting force. The results were compared.Findings: Stresses on connector in the 2mm connector group is lower than stresses on connector in the 1mm connector thickness group. Results: clinical significance of this study shows three unit (double abutments) buccally-retained RBFDPs with 2mm connector thickness are more reliable than three unit (double abutments) buccally-retained RBFDPs with 1mm connector thickness since main reported failure of RBFDPs are in connector areas. The advantage of using buccally retained RBFDPs is more retentive enamel area for cement and higher esthetic outcome.Key Words: (laminates, buccally-retained RBFDPs, FEA) 79

138 páginas. Maestría en Ciencias e Ingeniería de Materiales. En el presente trabajo se describe la estrategia de síntesis de materiales híbridos mediante la asociación de una matriz inorgánica y una molécula biológicamente activa. Los materiales sintetizados fueron evaluados como sistemas de liberación modulada de la molécula biológicamente activa. La matriz inorgánica consiste en una hidroxisal laminar de MgZn o FeZn y se utilizó para la encapsulación de ácido nalidíxico o ácido pipemídico, quinolonas de primera generación con actividad biológica contra bacterias Gram-negativas, así como algunas bacterias Gram-positivas. Los materiales híbridos así obtenidos fueron protegidos por un recubrimiento ácidorresistente, consistente de alginato de sodio. La eficacia del sistema recubierto fue evaluada en la liberación modulada de la molécula biológicamente activa a condiciones de temperatura y pH controlados. La caracterización de los materiales se llevó a cabo mediante difracción de rayos-X, análisis termogravimétrico, espectroscopia de infrarrojo por transformada de Fourier, microscopía electrónica de barrido y espectroscopia de dispersión de energía. Por otro lado, las pruebas de evaluación para el seguimiento de la liberación de las moléculas biológicamente activas se realizaron mediante un espectrofotómetro de ultravioleta visible utilizando membranas de diálisis con tamaño de poro de 1 k Da en agua destilada y en agua de peptona tamponada; en medios sintéticos de jugo gástrico biliar y en fluidos sintéticos del intestino delgado. Finalmente, se evaluó la actividad y sensibilidad bactericida de aquellos materiales asociados a las moléculas biológicamente activas. Adicionalmente algunas de las hidroxisales dobles laminares se caracterizaron mediante espectroscopia fotoelectrónica de rayos-X. Se realizó un análisis complementario de evaluación para la determinación cuantitativa del contenido del ácido nalidíxico en una de las hidroxisales de FeZn mediante un disolutor y se caracterizó por cromatografía líquida de alta eficiencia. Estos resultados se muestran en el apéndice B. Investigación realizada con el apoyo del Consejo Nacional de Ciencia y Tecnología (México). CONACYT.

Orientador: Carlos Henrique Daros Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica Resumo: Quando a sequência de empilhamento das lâminas não é simétrica em relação ao plano médio da placa laminada, os fenômenos de flexão e alongamento tornam-se inevitavelmente acoplados, o que proporciona um considerável aumento da complexidade das equações diferenciais governantes. Portanto, o acoplamento desses efeitos deve ser levado em consideração a fim de estabelecer uma formulação capaz de analisar laminados gerais, sejam esses simétricos ou assimétricos. Recentemente, uma formulação em elementos de contorno para a análise de placas finas laminadas que leva em consideração o referido acoplamento foi desenvolvida. As equações integrais de contorno foram obtidas com o auxílio do teorema da reciprocidade de Betti-Rayleigh e as respectivas soluções fundamentais foram derivadas por meio de um formalismo complexo análogo ao de Stroh. Neste trabalho, essa formulação é estendida, mediante o emprego da técnica de sub-regiões, para a análise de estruturas tridimensionais formadas a partir da associação de placas finas laminadas. Seguindo essa abordagem, cada placa é analisada separadamente e então unida às demais por meio da imposição das condições de equilíbrio e de compatibilidade de deslocamentos ao longo das interfaces. Além disso, as integrais de domínio relacionadas com forças distribuídas na superfície da placa são transformadas em integrais de contorno por meio do método da integração radial. Alguns exemplos são apresentados e os resultados obtidos são comparados com soluções analíticas e numéricas encontradas na literatura técnica ou, na ausência dessas, com valores fornecidos por um software comercial de elementos finitos, o que permite verificar a validade, confiabilidade e precisão da formulação apresentada. Por fim, uma vez que os códigos desenvolvidos são capazes de simular estruturas compostas por laminados com sequências de empilhamento arbitrárias, são formulados alguns problemas de otimização utilizando o fator de segurança associado com o critério de falha de Tsai-Wu como função objetivo e as orientações angulares das fibras de cada uma das lâminas como variáveis de projeto Abstract: When the laminae stacking sequence is non-symmetrical with respect to the midplane of the laminated plate, the coupling of in-plane and plate bending problems unavoidably arises, increasing the complexity of the governing differential equations. Thus, the coupling effects must be taken into account in order to establish a formulation able to cover all sorts of symmetric or unsymmetric laminates. Recently, a boundary element formulation for the coupled stretching-bending analysis of thin laminated plates has been developed. The related boundary integral equations were obtained with the aid of the Betti-Rayleigh reciprocal theorem and the fundamental solutions were derived through the use of a Stroh-like complex variable formalism. Here, this formulation is extended to cover problems of assembled thin laminated plate structures by means of the subregions technique. Following this approach, each plate is considered separately and then joined together by imposing equilibrium conditions and displacement compatibility along interface edges. Furthermore, domain integrals related to distributed loads are transformed into boundary integrals using the radial integration method. Some examples are presented and obtained results are compared with analytical and numerical solutions found in the technical literature or, in the absence of these solutions, with values provided by a finite element software, certifying the validity, reliability, and accuracy of the present formulation. Finally, since the resulting boundary element code is able to simulate structures composed by laminates with arbitrary stacking sequences, some optimization problems are stated, using the safety factor associated with the Tsai-Wu failure criteria as objective function and fibers orientation angles as design variables Mestrado Mecânica dos Sólidos e Projeto Mecânico Mestre em Engenharia Mecânica FAPESP 2017/12205-7 CAPES 33003017

Laminated glass combines glass layers, which provide strength and durability, with transparent polymeric interlayers, which provide coupling between glass layers and prevent glass shards from scattering in case of breakage. The main goal of this paper is to present, through COMSOL Multiphysics simulations, how the mechanical performance (bending stiffness and stress distribution) of laminated glass plates is affected by the shear stiffness of the interlayer material. The simulation results were validated with experimental tests. The laminated glass specimens presented a linear elastic behaviour until glass breakage, and its mechanical performance was affected by the interlayer material selection, as well as the load duration and the working temperature. The work was partially funded by CRISTEC with CDTI funds (IDI-20160588). The authors would like to thank the Catalan Government for the quality accreditation given to their research group GREiA (2017 SGR 1537). GREiA is certified agent TECNIO in the category of technology developers from the Government of Catalonia. This work is partially supported by ICREA under the ICREA Academia programme. Xavier Centelles would like to thank University of Lleida for his research fellowship.

A thermodynamically consistent damage model for the simulation of progressive delamination under variable mode ratio is presented. The model is formulated in the context of the Damage Mechanics. The constitutive equation that results from the definition of the free energy as a function of a damage variable is used to model the initiation and propagation of delamination. A new delamination initiation criterion is developed to assure that the formulation can account for changes in the loading mode in a thermodynamically consistent way. The formulation proposed accounts for crack closure effets avoiding interfacial penetration of two adjacent layers after complete decohesion. The model is implemented in a finite element formulation. The numerical predictions given by the model are compared with experimental results

A damage model for the simulation of delamination propagation under high-cycle fatigue loading is proposed. The basis for the formulation is a cohesive law that links fracture and damage mechanics to establish the evolution of the damage variable in terms of the crack growth rate dA/dN. The damage state is obtained as a function of the loading conditions as well as the experimentally-determined coefficients of the Paris Law crack propagation rates for the material. It is shown that by using the constitutive fatigue damage model in a structural analysis, experimental results can be reproduced without the need of additional model-specific curve-fitting parameters

Available failure criteria for the design of laminated composite structures do not explicitly take into account the occurrence of delaminations induced by matrix cracks. However, depending on the material properties, laminate stacking sequence and ply thickness, this failure mode may appear and compromise the structural integrity of the structure. In this work, a failure criterion for predicting matrix cracking induced delamination in laminated composites is presented. The failure criterion is developed within the framework of Fracture Mechanics, by comparing the energy release rate available for delamination extension near a matrix crack and the fracture toughness of the interface. The predicted failure loads agree well with experimental data available in the literature, thus supporting the introduction of this failure criterion into the set of failure criteria usually considered in composite's structural design This work was funded by AIRBUS under the project iComp - integrated method for the structural design of Composite components. The authors gratefully acknowledge the support provided by AIRBUS. In addition, the support of the Spanish government through DG-CICYT under Contract DPI2012-34465 and MAT2012-37552-C03-03, is acknowledged

CAPES A otimização global eficiente (ego, do inglês efficient global optimization), apresentada por Donald R. Jones no final da década de 90, tem como proposta solucionar problemas de otimização nos quais, devido a um elevado custo computacional da função objetivo, o número de avaliações desta é severamente limitado. ego baseia-se na otimização pelo uso de superfícies de resposta ou metamodelos, que são funções de baixo custo computacional que se ajustam aos dados “experimentais” (de experimentos físicos, cálculos analíticos ou simulações numéricas) obtidos em pontos escolhidos no domínio de projeto. Como no trabalho original de Jones, o metamodelo de Kriging é aqui utilizado. A eficiência e robustez do método reside no balanceamento entre a necessidade de minimização (ou maximização) da superfície de resposta média com a necessidade de melhoria da aproximação que esta fornece. Nesta dissertação, usa-se o ego para encontrar as orientações curvas de laminados de rigidez variável com geometrias relativamente complexas. Os problemas mostrados possuem número moderado de variáveis (em geral 12) e geometrias que variam de uma simples placa quadrada com furo central a painéis reforçados semelhantes a seções de fuselagem de uma aeronave comercial. Através desses problemas, são abordadas a otimização global com e sem restrições e a otimização multiobjetivo sem restrições. Para contemplar restrições e multiobjetivos, foi necessária a implementação de modificações no algoritmo original de Jones. Para a maior parte dos problemas, o orçamento computacional é restringido em apenas 60 avaliações dos modelos de alta fidelidade (modelos de elementos finitos desenvolvidos no software ansys). Os resultados obtidos mostram que o framework proposto é capaz de encontrar bons projetos para um orçamento computacional limitado. Em relação aos compósitos de rigidez variável, o uso de fibras curvas mostrou ganhos estruturais substanciais. Por exemplo, para a estrutura semelhante à de uma fuselagem de aeronave, chegou-se a observar um aumento de até 47% na carga de flambagem sob carregamento de compressão uniaxial, quando comparada à mesma estrutura com apenas fibras retas comerciais. The efficient global optimization (ego), presented by Donald R. Jones at the end of the 90s, propose to solve optimization problems where, due to the high computational burden of the cost function, the number of evaluations is severely limited. ego is based on the concept of surrogate models, that are fast-to-compute functions that adjust the “experimental” data (physical, analytic or simulations). In the current work, as well as in the Jones’s one, the Kriging metamodel is used. The efficiency and robustness of the method lays at the balance between exploration and exploitation of the surrogate response. Here, ego is used to find the optimized parameters for curved fiber structures with relatively complex geometry. The number of variables are moderately (in general 12) for the various problems presented and the geometries vary from simple square plates with a central hole to an airplane fuselage-like section. Trough these problems, single objective optimizations with and without constraints and an unconstrained multiobjective optimization are performed. For the constraints and multiobjectives, adaptations to the original framework were made. For most of the problems, the computational budget is set to just 60 evaluations of the high fidelity model (finite element model built using ANSYS software). The results showed that the framework is capable of finding good designs with a limited computational budget. Considering the variable stiffness composites, the use of curved fibers presented substantial structural improvements. For example, for the fuselage-like structure, it was observed an improvement of 47% in the buckling load when compared to straight fibers optimal solution.

Delaminations at the free-edges of a laminated composite under tension can be triggered by transverse cracks or by high interlaminar stresses. The capability for predicting these phenomena when the ply thickness is reduced (thin-ply laminates) is particularly challenging because damage mechanisms are delayed or even suppressed. In this work, an existing energy-based failure criterion and a simplified finite element model with cohesive elements are combined to develop a computationally inexpensive predictive tool. Its comparison with experimental data demonstrates that this approach captures the trends of the critical strain for delamination with respect to ply thickness and ply location and the quantitative agreement with the predictions is satisfactory The authors acknowledge the financial support of the Spanish government through the Ministerio de Economía y Competitividad under the contracts DPI2012-34465 and MAT2012-37552-C03-03, which is partially funded by the FEDER funds of the EC. The first author acknowledges the support of the Generalitat de Catalunya with the pre-doctoral grant FI-DGR (2014FI B1 00123). The company CHOMARAT (Ardèche, France) is acknowledged for providing the NCF material and Aldila (Poway, California, USA) for the epoxy system pre-preg. The company AIRBUS partially funded this work through the 2genCOMP project

This paper looks at the results of measurement of thermal resistance by testing laminated materials. In this case, new original patented system of measurement was used to determine static and dynamic thermal properties of fabric surfaces, composition and clothes. As we mentioned before, this patented system of measurement was developed, installed and calibrated in Laboratory for process parameters in Department of clothing technology Faculty of Textile technology of the University of Zagreb. Its fundamental feature is technically complete connectivity, so as originality and accuracy and compatibility of tested parameters.

This thesis work consists of two main parts: Deter-mination of residual stresses in composites laminates ±θ, introduced by the thermal cycle during the manufacturing process of laminates and Study of their influences on the mechanical behavior of these laminates. Limited by the current theory, the exper-imental determination of residual stresses in the laminates ±θ was very difficult. In this work, the incremental hole drilling method was performed for the residual stresses relaxation and then the gener-ated strains around the hole were measured with strain gages. The new approach proposed in this thesis allows associating the strains around the hole and the residual stresses in the laminates ±θ. The calibration coefficients were determined by the numerical simulation. With this approach, we found a linear relationship between the residual stresses and the fiber orientation angle θ for the composite laminates [02/θ2]s. By adapting a thermoelastic ma-terial model, the results obtained by our new ap-proach were modelized by the numerical study. Then we studied the influence of laminate thickness, curing cycle and hydrothermal ageing on the distri-bution of residual stresses. With the help of acoustic emission technique, the influences of the residual stresses on the damage and the mechanical behavior of composite laminates were studied through tensile tests. Finally, the importance of the residual stresses on the transverse failure of composite laminates was demonstrated comparing with the theoretical results, Cette thèse comprend deux parties : Détermination des contraintes résiduelles dans les composites stratifiés ±θ induites par le cycle thermique de fabrication et Étude de leurs influences sur le comportement mécanique de ces stratifiés. Limitée par la théorie actuelle, la détermination expérimentale des contraintes résiduelles dans les stratifiés ±θ a été très difficile. Dans notre étude, la méthode du trou incrémental a été employée afin de relaxer les contraintes résiduelles et les déformations provoquées ont été mesurées par les jauges de déformation. Une nouvelle approche proposée dans cette thèse permet d’associer les déformations autour du trou et les contraintes résiduelles au sein du stratifié ±θ. Les coefficients de calibration ont été déterminés par la simulation numérique. Grâce à l’approche développée, nous avons constaté une relation linéaire entre les contraintes résiduelles et l’angle θ du stratifié [02/θ2]s. En adaptant un modèle thermoélastique du matériau, les résultats expérimentaux ont pu être modélisés numériquement. Ensuite, nous avons étudié l’influence de l’épaisseur du stratifié, du cycle de cuisson et du vieillissement hydrothermique sur la distribution des contraintes résiduelles. A l’aide de la technique d’émission acoustique, les influences des contraintes résiduelles sur l’endommagement et le comportement mécanique des stratifiés ont été étudiées grâce aux essais de traction. Enfin, l’importance des contraintes résiduelles sur la rupture transversale du stratifié a été mise en évidence en comparant avec les résultats théoriques

Submitted by Paulo Frazão (pfrazao@lnec.pt) on 2015-03-19T10:07:39Z No. of bitstreams: 1 Feasibility of Creosote Treatment for Glued-Laminated Pine-Timber Railway Sleepers.pdf: 3420148 bytes, checksum: 5a81d6a87142bcdb988a4032ad6211b1 (MD5) Approved for entry into archive by Ana Duarte (aduarte@lnec.pt) on 2015-03-19T12:10:32Z (GMT) No. of bitstreams: 1 Feasibility of Creosote Treatment for Glued-Laminated Pine-Timber Railway Sleepers.pdf: 3420148 bytes, checksum: 5a81d6a87142bcdb988a4032ad6211b1 (MD5) Made available in DSpace on 2015-03-19T12:10:33Z (GMT). No. of bitstreams: 1 Feasibility of Creosote Treatment for Glued-Laminated Pine-Timber Railway Sleepers.pdf: 3420148 bytes, checksum: 5a81d6a87142bcdb988a4032ad6211b1 (MD5) Previous issue date: 2015-03 Made available in DSpace on 2017-04-12T13:44:10Z (GMT). No. of bitstreams: 2 license.txt: 1824 bytes, checksum: 0e8f0a2b3297cbff76e4756d4aa25e10 (MD5) Feasibility of Creosote Treatment for Glued-Laminated Pine-Timber Railway Sleepers.pdf: 3420148 bytes, checksum: 5a81d6a87142bcdb988a4032ad6211b1 (MD5) Previous issue date: 2015-03 11p The authors would like to thank the company Tecnocarril - Sociedade de Serviços Industriais e Ferroviários, Lda. for providing access to their treatment facilities, as well as support and assistance during the treatment 27, issue 3 DE/NCE Journal of Materials in Civil Engineering

Nowadays the use of composite materials is really common in industries because of its low weight in comparison with its structural benefits. In aeronautic industries, there is a constant interest in lightening all of its components. Especially on civil aircraft fuselages which are done with skin and reinforcements. One of the design’s objectives of this skin is to avoid buckling. Our objective is to create a laminate that can accomplish the fuselage’s skin’s requirements reducing its weight and preserving its mechanical integrity

An experimental program was performed at IVALSA Trees and Timber Institute on single and coupled cross-laminated (CLT) wall panels with different anchoring systems and different types of joints between adjacent panels. The mechanical properties of CLT walls were assessed and are critically discussed in the paper. The connector layout and the design of the screwed vertical joints were found to markedly affect the overall behavior of the structural system. The in-plane deformations of CLT panels were almost negligible, whereas concentration of forces and deformations mainly occurred in the connections. Advanced analytical models for nonlinear pushover analysis of CLT wall systems were developed and verified against test results. The models take into account all stiffness and strength components of connectors, as well as the bending and shear deformation of the panels. A parametric study of CLT wall systems with different aspect ratios and wall segmentation was performed, showing that segmentation of CLT walls decreases their stiffness and strength but significantly improves their deformation capacity.

This thesis is part of the nonintrusive coupling methods framework which allow to merge to kind of software : general commercial software and dedicated software.The aim is to apply such coupling for the analysis of assembly of laminated plates.In fact, the behavior in composite material around critical zones requires to take in account complex phenomena (in 3D), whereas the industrial way of work is to simplify the structure with plate or shell model in order to handle very large structures.The nonintrusive coupling method developed here allow to virtually apply a 3D patch to the plate model in order to enriched the global description without any modification of the global meshes, models, or solver.Various methods of coupling and improvement to the classical nonintrusive coupling are proposed., Cette thèse s'inscrit dans le cadre des méthodes de couplage non-intrusives qui permettent de concilier deux types de logiciels : logiciels commerciaux généralistes et logiciels dédiés. L'objectif est d'appliquer un tel couplage pour le traitement des assemblages de plaques stratifiées.En effet, le comportement aux environs des zones critiques de ces matériaux composites nécessite une prise en compte fine (3D) des phénomènes en jeu alors que la pratique industrielle consiste à représenter les structures par des modèles simplifiés de plaques ou de coques.La méthode non-intrusive développée ici permet ainsi de « patcher » virtuellement le modèle plaque par des modèles 3D locaux, de coupler fortement le modèle global avec les patchs, sans modifier les maillages ni les modèles.Diverses stratégies de raccords sont envisagées, ainsi que des améliorations à la technique de couplage.

This thesis is part of the nonintrusive coupling methods framework which allow to merge to kind of software : general commercial software and dedicated software.The aim is to apply such coupling for the analysis of assembly of laminated plates.In fact, the behavior in composite material around critical zones requires to take in account complex phenomena (in 3D), whereas the industrial way of work is to simplify the structure with plate or shell model in order to handle very large structures.The nonintrusive coupling method developed here allow to virtually apply a 3D patch to the plate model in order to enriched the global description without any modification of the global meshes, models, or solver.Various methods of coupling and improvement to the classical nonintrusive coupling are proposed., Cette thèse s'inscrit dans le cadre des méthodes de couplage non-intrusives qui permettent de concilier deux types de logiciels : logiciels commerciaux généralistes et logiciels dédiés. L'objectif est d'appliquer un tel couplage pour le traitement des assemblages de plaques stratifiées.En effet, le comportement aux environs des zones critiques de ces matériaux composites nécessite une prise en compte fine (3D) des phénomènes en jeu alors que la pratique industrielle consiste à représenter les structures par des modèles simplifiés de plaques ou de coques.La méthode non-intrusive développée ici permet ainsi de « patcher » virtuellement le modèle plaque par des modèles 3D locaux, de coupler fortement le modèle global avec les patchs, sans modifier les maillages ni les modèles.Diverses stratégies de raccords sont envisagées, ainsi que des améliorations à la technique de couplage.

One of the main purposes for an accurate strength prediction is to get a reliable design tool of a given structure. Since most of aircraft and aerospace structures contain many holes and are subject to multidirectional loading conditions, due to stress concentration, cracks will necessarily emanate from these holes before failure. Therefore, the nominal strength prediction of open hole specimens under biaxial loading conditions is very necessary for the safe design of these structures. The main goal of this work is to develop an analytical model able to predict the nominal strength and the failure envelope of isotropic quasi-brittle open hole specimens under biaxial loading conditions. In this model, the nominal strength is analyzed taking into account the hole radius and the biaxiality load ratio. The model is formulated based on the cohesive zone model considering various shapes of the cohesive law. Other approaches such as the different methods of the critical distance theories are also presented and compared with the results of the cohesive crack model The first author would like to thank Generalitat de Catalunya for the FI pre-doctorate grant 2012FI. The authors acknowledge the financial support of the Ministerio de Ciencia e Innovacion under the project MAT2012-37552-C03-03

Bu çalışmada PVB ile birbirine bağlanmış iki cam levhadan oluşan lamina cam eğrisel kiriş ve silindirik kabuk yapının çözümlenmesi yapılmıştır. Lamina cam eğrisel kiriş ve kabuklar mimari, havacılık, otomobil ve uçak endüstrisinde kullanılırlar. Eğrisel kirişler ve kabuk yapılar eğrilikleri nedeniyle düzlemsel yapılardan farklıdırlar. Matematiksel karmaşıklıkları nedeniyle yapılan çalışmaların bir çoğu eğrisel kiriş ve kabuk elemanların doğrusal olmayan davranışlarından ziyade doğrusal olan davranışları ile ilgilidir. Dolayısıyla eğrisel kiriş ve kabukların davranışını çözümlemek için büyük yerdeğiştirmeler kuramını dikkate alan bir matematiksel model geliştirilmesi gerekmektedir. Lamina cam yapılar ince olmaları nedeniyle kolayca büyük yerdeğiştirmeler gösterdiklerinden ve malzemelerin elastisite modülleri arasındaki büyük farktan dolayı mekanik davranışları karmaşıktır. Daha açıklayıcı şekilde ifade edilirse camın elastisite modülü PVB aratabakanın elastisite modülünden yaklaşık 7*104 kez daha büyüktür. Doğrusal olamayan davranışları nedeniyle lamina camların gerçekçi çözümlemesi büyük yerdeğiştirmelerin etkisi gözönüne alınarak yapılması gerektiğinden eğrisel kiriş ve kabukların doğrusal olmayan hakim denklemlerini elde etmek için değişim ve minimum potensiyel enerji ilkeleri kullanılarak matematiksel model geliştirilmiştir. Yerdeğiştirmeleri elde etmek için tekrarlamalı çözüm yöntemi kullanılmıştır. Türetilen doğrusal olmayan denklemleri sayısal çözmek için bilgisayar programı geliştirilmiştir ve elde edilen sayısal sonuçları doğrulamak için yapılan deneylerden ve sonlu elemanlar yönteminden elde edilen sonuçlar kullanılmıştır. Eğrisel kiriş ve kabukların davranışını açıklayan ve geliştirilen modelleri doğrulayan sonuçlar grafikler halinde verilmiştir. In this study, a laminated glass unit which consists of two glass sheets bonded together by PVB is analyzed as a curved beam and as a cylindrical shell. Laminated glass curved beams and shells are used in architecture, aerospace, automobile and aircraft industries. Curved beam and shell structures differ from straight structures because of their initial curvature. Because of mathematical complexity most of the studies are about linear behavior rather than nonlinear behavior of curved beam and shell units. Therefore it is necessary to develop a mathematical model considering large deflection theory to analyze the behavior of curved beams and shells. Mechanical behavior of laminated glass structures are complicated because they can easily perform large displacement since they are very thin and the materials with the elastic modulus have order difference. To be more precise modulus of elasticity of glass is about 7*104 times greater than the modulus of elasticity of PVB interlayer. Because of the nonlinearity, analysis of the laminated glass has to be performed by considering large deflection effects. The mathematical model is developed for curved beams and shells by applying both the variational and the minimum potential energy principles to obtain nonlinear governing differential equations. The iterative technique is employed to obtain the deflections. Computer programs are developed to analyze the behavior of cylindrical shell and curved beam. For the verification of the results obtained from the developed model, the results from finite element models and experiments are used. Results used for verification of the model and the explanation of the bahavior of the laminated glass curved beams and shells are presented in figures. 278

Bu çalışmada, ahşap dışındaki bir takım malzemelerin katılımıyla bu malzemelerin güçlü yanlarının kullanıldığı güçlendirilmiş kompozit ahşap yapı elemanı tasarımı gerçekleştirilmiş ve bazı teknik özellikleri belirlenmiştir. Bu amaçla, ahşap katmanlarda, yapılarda yaygın olarak kullanılması nedeniyle sarıçam (Pinus Sylvestris L.), ara katmanlarda ise gözenekli yapıdaki alüminyum ve fiber esaslı malzemeler kullanılmış, Polivinilasetat (PVAc) D3 ve Desmodur-VTKA tipi tutkallarla preslenerek 7'si masif 13 katmanlı lâmine kompozit malzeme haline getirilmiştir. Deneylerde, toplam 164 adet örnek üzerinde, yoğunluk, yapışma, eğilme direnci, eğilmede elastikiyet modülü ve basınç direnci belirlenmiş, elde edilen sonuçlar masif ve sadece masif malzemeden üretilen lamine ahşap malzemelere oranla test edilmiştir. Elde edilen 7 malzeme türü açısından 6 farklı deneyle elde edilen sonuçlar değerlendirildiğinde, basınç deneyinde ara katman malzemesi dışındaki etkenlerin önemli bir farklılığa neden olmadığı, bunun dışındaki tüm deney ve numuneler için kullanılan değişkenlerin (Tutkal, Ara katman malzemesi) etkili birer faktör olduğu görülmüştür. Bu bağlamda tüm deneyler açısından Poliüretan tutkalın mukavemeti artırdığı, yapışmada ara katman malzemesinin zayıflatıcı etki yaptığı, THP numunelerde ara katman malzemesinin tutkal ayrılmasına bağlı olarak güçlendirme etkisi bulunmadığı, özellikle fiber malzemenin malzemede elastiklik modülünü düşürerek elastikliği artırdığı ve en önemli sonuç olarak THD etkilere karşı ara katman malzemesinin yüksek oranda bir mukavemet artışı sağladığı, bu artışın alüminyum esaslı ara katman malzemesinde daha yüksek seviyede olduğu görülmüştür.Anahtar Kelimeler : Ağaç malzeme, kompozit, teknik özellikler In this study, reinforced composite timber structural element is designed with participation of some materials other than wood by using strong properties of these materials. The purpose of this study is to determine some technical properties of this structural element. For this purpose, solid pine (Pinus sylvestris L.) is used in the layers of solid wood as it is widely used in wood structures; aluminum and fiber materials in the porous structure are used between layers of solid wood. All these materials are pressed by using glue type Polyvinyl acetate (PVAc) and Desmodur-VTKA and has become laminated composite material. This composite consists of 13 layers of which 7 are solid wood and 6 are porous materials. In this experiment; the density, adhesion, flexural strength, flexural modulus of elasticity, compression set resistance of a total of 164 samples were determined. Obtained results are compared with the properties of solid wood and laminated wood. At the end; it is observed that every factor except the porous materials used in the composite sample are statistically not significant in the compression set resistance experiment; and every factor (glue, porous materials) used in composite sample are statistically significant in the density, adhesion, flexural strength, flexural modulus of elasticity experiments. In conclusion, in all the experiments; type Desmodur-VTKA glue raised the strength, porous materials attenuated the bonding, porous materials attenuated strength in the parallel force to the line of glue, specially fiber material enhance flexural performance of composite material by decreasing the flexural modulus of elasticity. As the most important result; porous materials highly enhance strength in the effects of perpendicular to the line of glue, and this strength is better in aluminum material than fiber material.Key Words : Wood materials, composite, technical properties. 92

Bu tez çalışmasında, ayrık tekil konvolüsyon (ATK) kullanılarak elastik zemine oturan tabakalı kompozit plakların lineer olmayan statik analizi yapılmıştır. Winkler-Pasternak iki parametreli zemin modeli kullanılmıştır. Winkler zemin için lineer olmayan parametre dikkate alınmıştır. Lineer olmayan deplasmanların üzerine pek çok parametrenin etkisi incelenmiştir. In this thesis, nonlinear static analysis of laminated composite plates resting on elastic foundations has been investigated by discrete singular convolution method. Winkler- Pasternak foundation model is used. Nonlinear parameter has been taken into consideration for Winkler model. The effects of many different parameters on nonlinear displacements are investigated. 82

O atual ambiente de negócios caracteriza-se pela frequência e velocidade de mudanças políticas, socioeconômicas, culturais e tecnológicas. Diante desse contexto de mudanças, surge à necessidade das organizações se tornarem flexíveis e adaptáveis para se adequar a esse novo ambiente. O presente estudo tem como objetivo geral analisar os sistemas logísticos, utilizando um modelo matemático, para a tomada de decisão da melhor alternativa de transporte na distribuição física dos produtos em uma indústria produtora de laminados de madeira. Além do objetivo geral, o estudo também propõe avaliar a possibilidade da distribuição física através as diversas combinações dos modais de transportes. Definir um modelo de redes logísticas que facilite a análise e definição da melhor alternativa de transporte e, por fim, avaliar através do modelo matemático, fatores relacionados a custo, tempo e risco da operação logística de diferentes opções de transportes. Para consecução dos objetivos do trabalho a abordagem metodológica utilizada caracteriza-se como: indutiva, aplicada, qualitativa e quantitativa, exploratória e realizada sob a forma de levantamento. Através das variáveis que compõem o modelo (custo, tempo e isco), os resultados evidenciam o benefício da utilização do modelo matemático que gerou dados confiáveis para tomada de decisão que possibilitou ganhos na operação de transporte independentemente da localização geográfica, podendo adequar-se para atender as sazonalidades do mercado, priorizando a variável de maior importância para cada necessidade da distribuição física. The current business environment is characterized by the frequency and speed of political changes, socioeconomic factors, cultural and technological. On this context of changes, comes the need for organizations to become flexible and adaptable to suit this new environment. This study aims to analyze logistics systems, using a mathematical model for decision making of the best alternative transportation in the physical distribution of products in an industry producing laminated wood. Besides the general purpose, the study also proposes to assess the possibility of physical distribution through the various combinations of transportation modes. Define a logistic network models that facilitates the analysis and definition of the best transportation alternative, and finally, by evaluating the mathematical model, factors related to cost, time and risk of the logistics operation of different transport options. To achieve the objectives of the work, the methodological approach is characterized as inductive, applied, qualitative and quantitative, exploratory and conducted in the form of survey. Through the variables that make up the model (cost, time and risk), the results show the benefit of using the mathematical model that generated reliable data for decision making that possible gains in the transport operation independent of geographical location, and can adapt to meet the seasonality of the market, prioritizing the most important variable for every need of physical distribution.

Bu çalışmada, ağaç işleri endüstrisi ve mobilya üretiminde birçok kullanım alanı bulan sarıçam (Pinus Sylvestris L.) odunu kullanılmıştır. Lamine malzemelerin yapımında kullanılacak olan kaplamalar, 5 mm kalınlığında, 70 mm genişlik ile 400 mm uzunluğunda kesme yöntemiyle hazırlanmıştır. Deney örnekleri 4 farklı sıcaklık (110 °C, 130 °C, 150 °C ve 170 °C) ve 3 farklı süre (2- 4- 6 saat) olmak üzere toplam 12 farklı kombinasyonda ısıl işlem uygulaması yapılmıştır. Örnekler fenol formaldehit tutkalı ile 4 katmanlı olacak şekilde 120 °C sıcaklıkta, 2,5 kg/cm2 pres basıncı altında 15 dakika preslenerek lamine ağaç malzemeler elde edilmiştir.Deney örneklerinin liflere paralel basınç direnci, eğilmede elastikiyet modülü, liflere paralel çekme direnci, dinamik eğilme (şok direnci), eğilme direnci ve eğilmede elastikiyet modülü değerleri belirlenmiştir.Sonuç olarak; en yüksek liflere paralel basınç direnci değeri 54,90 N/mm2 olarak, en yüksek eğilmede elastikiyet modülü değeri 10677,04 N/mm2 olarak ve kontrol grubu örneğine göre artış olduğu tespit edilmiştir. En yüksek eğilme direnci değeri 86,53 N/mm2 olarak kontrol grubu örneğinde, en yüksek dinamik eğilme (şok direnci) değeri 2,00 kN/cm2 olarak kontrol grubu örneğinde, en yüksek liflere paralel çekme direnci değeri 9266,31 N/mm2 olarak 110 °C de 2 saat süre ile bekletilen deney örneğinde olduğu tespit edilmiştir. Deney örneklerinin mekanik özelliklerinde ortalama %7-%20 arasında düşüş olduğu tespit edilmiştir. In this study, scots pine wood (Pinus Sylvestris L) which many using areas in furniture production and wood working industry was used. The veneers was used to produce laminated material, which is 5 mm thick, 70 mm wide and 400 mm lenght was prepeared by cutting method. Testing samples were applicated 12 different combination of heat treatment in 4 different heat (110 °C, 130 °C, 150 °C, 170 °C) and in 3 different periods (2- 4- 6 hours). The samples that are applied heat treatment were transformed to 4 layered laminated material that is joined with phenol formaldehyde resin, in 120 °C heat, pressed 15 minutes under the pressure of 2,5 kg/cm2.The mechanical properties; compression strength parallel to the grain, modulus of rupture (MOR), modulus of elasticity (MOE) rates of the testing samples were tested.As a result, some decreases were obtained in static bending (MOR), dynamic bending, tension strength parallel to the grain. However an increase was obtained in modulus of elasticity in bending (MOE) and compression strength parallel to the grain. 78

Los materiales compuestos laminados son de más en más usados en el sector de la aeronáutica y del espacial ya que juntan una pequeña densidad, buenas propiedades mecánicas (resistencia y rigidez elevadas) y una pequeña sensibilidad a la corrosión (fuselaje totalmente en materiales compuestos para el Boeing 787, y 52% de la estructura del Airbus A350 XWB). No obstante, esos materiales tienen el inconveniente de presentar modos de deterioración complejos que pueden sobrevenir mucho antes de la ruptura final y con los cuales la estructura tiene que cumplir sus funciones. El dimensionamiento clásico de las estructuras consiste en el cálculo de criterios de ruptura (en la industria, esfuerzos o deformaciones máximas, pero también los criterios de Hill o Tsaï-Wu). Sin embargo, estos criterios no tienen en cuenta la deterioración del material y de su influencia sobre la curva de comportamiento de la estructura. Así pues, es interesante de utilizar herramientas que tienen en cuenta los fenómenos de daño para dimensionar de la mejor manera posible las estructuras. Para eso, usaremos en este proyecto programas desarrollados en el marco de las actividades I+D de la empresa Medysys Air Espace: - DAMSTRAT, programa de análisis por elementos finitos especializado en el daño intra laminar (micro fisuras, descohesión fibra/matriz…) progresivo de los materiales compuestos que trabaja en calculo no linear, - CLEOPS (Composite Local Effects Of Plates & Shells), programa que permite calcular las tensiones 3D elásticas situadas sobre los bordes de una estructura, con un método asintótico y una resolución por elementos finitos acoplada con una resolución espectral. Utilizaremos este programa con el fin de estudiar los daños inter laminares o deslaminación (despegadura entre dos capas del material). El objetivo de este proyecto es estudiar los fenómenos de daño intra laminares con DAMSTRAT para geometrías particulares, representativas de formas industriales clásicas (placas de espesor variable, y placas agujereadas), y luego prever y localizar la iniciación de la deslaminación con CLEOPS, comprobando los resultados numéricos con los resultados de los ensayos. En ambas geometrías, tres estratificaciones del material han sido estudiadas. Para la primera geometría, dos configuraciones (representativas de las configuraciones que se puede obtener en la industria) han sido estudiadas. Este estudio permite comparar cómo se comporta el daño intra laminar en ambos casos, de analizar en que configuración son las probetas de los ensayos y de determinar la cual es la más sensible a la deslaminación. Los resultados han mostrado que la configuración “vacio” es la más propicia al daño intra laminar y a la deslaminación, y que no deslaminación aparecía en ambos casos. Para la segunda geometría, la iniciación de la deslaminación ha sido prevista con una precisión entre 10% y 20%, y las zonas de deslaminación han sido determinadas. Un estudio complementario podría ser realizado utilizando un criterio de deslaminación basado sobre los fenómenos de creación de la deslaminación para obtener resultados más precisos (el criterio tipo “cuadrático” usado en este proyecto puede ser inoperante en ciertos casos).

Los materiales compuestos laminados son de más en más usados en el sector de la aeronáutica y del espacial ya que juntan una pequeña densidad, buenas propiedades mecánicas (resistencia y rigidez elevadas) y una pequeña sensibilidad a la corrosión (fuselaje totalmente en materiales compuestos para el Boeing 787, y 52% de la estructura del Airbus A350 XWB). No obstante, esos materiales tienen el inconveniente de presentar modos de deterioración complejos que pueden sobrevenir mucho antes de la ruptura final y con los cuales la estructura tiene que cumplir sus funciones. El dimensionamiento clásico de las estructuras consiste en el cálculo de criterios de ruptura (en la industria, esfuerzos o deformaciones máximas, pero también los criterios de Hill o Tsaï-Wu). Sin embargo, estos criterios no tienen en cuenta la deterioración del material y de su influencia sobre la curva de comportamiento de la estructura. Así pues, es interesante de utilizar herramientas que tienen en cuenta los fenómenos de daño para dimensionar de la mejor manera posible las estructuras. Para eso, usaremos en este proyecto programas desarrollados en el marco de las actividades I+D de la empresa Medysys Air Espace: - DAMSTRAT, programa de análisis por elementos finitos especializado en el daño intra laminar (micro fisuras, descohesión fibra/matriz…) progresivo de los materiales compuestos que trabaja en calculo no linear, - CLEOPS (Composite Local Effects Of Plates & Shells), programa que permite calcular las tensiones 3D elásticas situadas sobre los bordes de una estructura, con un método asintótico y una resolución por elementos finitos acoplada con una resolución espectral. Utilizaremos este programa con el fin de estudiar los daños inter laminares o deslaminación (despegadura entre dos capas del material). El objetivo de este proyecto es estudiar los fenómenos de daño intra laminares con DAMSTRAT para geometrías particulares, representativas de formas industriales clásicas (placas de espesor variable, y placas agujereadas), y luego prever y localizar la iniciación de la deslaminación con CLEOPS, comprobando los resultados numéricos con los resultados de los ensayos. En ambas geometrías, tres estratificaciones del material han sido estudiadas. Para la primera geometría, dos configuraciones (representativas de las configuraciones que se puede obtener en la industria) han sido estudiadas. Este estudio permite comparar cómo se comporta el daño intra laminar en ambos casos, de analizar en que configuración son las probetas de los ensayos y de determinar la cual es la más sensible a la deslaminación. Los resultados han mostrado que la configuración “vacio” es la más propicia al daño intra laminar y a la deslaminación, y que no deslaminación aparecía en ambos casos. Para la segunda geometría, la iniciación de la deslaminación ha sido prevista con una precisión entre 10% y 20%, y las zonas de deslaminación han sido determinadas. Un estudio complementario podría ser realizado utilizando un criterio de deslaminación basado sobre los fenómenos de creación de la deslaminación para obtener resultados más precisos (el criterio tipo “cuadrático” usado en este proyecto puede ser inoperante en ciertos casos).

Yüksek Lisans Tezi Günümüzde silahlı saldırılardan korunmak için çeşitli yollar vardır. Bunların içinde en zararsız olanları şüphesiz karşı tarafa zarar vermeden kendini korumaktır. Kişilerin kendini koruma yollarının başında da araçlarını veya yaşam alanlarını silahlı saldırılara karşı mukavemetli elemanlar ile kaplamaları gelmektedir. Bu elemanlardan bir tanesi olan güvenlik camları, çarpma, patlama, kırılma sırasında küçük ama zararsız parçalara ayrılan, ancak çerçesi içinde kalarak dağılmayan camlardır. Bu özelliklerin sağlanabilmesi için lamine camlar en doğru çözüm gibi görünmektedir. PVB (Polivinil bütiral) veya polikarbonat ara katmanlı laminasyonlu birleşimler olan bu camlar kırılsa dahi çerçevesinin içinde, birarada kalarak etrafa dağılan tehlikeli parçalar olmaktan çıkar. Ancak her lamine camın darbe ve patlamalara karşı dayanıklı olduğu söylenemez. Bu aşamada birleşim katmanlarının fiziksel özellikleri ve kalınlıkları, bitmiş ürünün çerçevesi ile ilişkisi önem kazanmaktadır. Bu çalışma, kurşun geçirmez camların üretim prosesi ve kurşun geçirmez camların balistik testler incelenmiştir. Anahtar Kelimeler: Güvenlik camları, Kurşun geçirmez cam, Polyvinil Bütiral (PVB), lamine, balistik Abstract Nowadays there are several ways to defend from armed attack. Harmless methods in these ways defend yourself with giving any damage to other side. At the top of defending oneself, one should cover one's habitat and vehicular with resisting components to save from armed attack. The resisting component which is called security glass goes to small and harmless pieces at crashing, exploding and breaking; however it saves the position and doesn't disperse. The best solution for providing these properties is lamine glass. This glass is a combination with lamination of PVB or polycarbonate and if it is broken, pieces of glass don't go out of the area and don't be dangerous. Nevertheless, we cannot say that every lamine glass is resistant to strokes and explosions. In this stage, the relationship between finished production's frame, the physical properties and thicknesses of combination layers are very important. This study is investigated the production project of bulletproof glasses and ballistic tests of bulletproof glasses. Keywords: Security glass, bulletproof glass, PolyVinyl Butyral (PVB), laminate, ballistic

Bu çalışmada bir membran tabakası ya da kaplama tabakası içeren kompozit yapıdaki su-geçirmez ancak nefes alabilir (su buharı geçirgen) tekstil kumaşlarının konfor özellikleri incelenmiştir.Burada test edilen numuneler dünyanın bu alanda önde gelen üreticilerinden temin edilmiş olup, her biri kendi içerisinde spesifik membran ve kompozit yapı karakterine sahiptir. Bu yapıların özellikle soğuk hava şartlarında giyilen yüksek performanslı giysiler için taşıdığı önem oldukça büyüktür. Ayrıca yüksek katma değerli ürünler grubunda yer almaktadırlar.Su-geçirmez, nefes alabilen çok katmanlı giyim ürünlerinde görülen en önemli konfor sorunu, su buharı geçirgenliğinden kaynaklanmaktadır. Bu yapıların vücudun ürettiği teri, buhar formundayken (0,4 nm) dışarıya atmaları gerekmektedir. Aksi takdirde özellikle soğuk hava şartlarında vücutta biriken nem, düşük hava sıcaklığının etkisiyle soğumakta ve vücut ısısının normalin altına düşmesine (hypothermia) sebep olabilmektedir. Diğer parametreler hava geçirgenliği, su-geçirmezlik, ısı iletkenliği gibi konfor parametreleridir.Bu çalışmada, yukarıda bahsedilen yapıların konfor özelliklerine etki eden; ortam koşulları, vücut ile giysi arasındaki hava boşluğu, giysilerin üretiminde kullanılan malzemelerin ve kompozit yapının kalınlığı gibi parametreler incelenmiştir. Numunelerin seçimi ve temininden sonra; sırasıyla su buharı geçirgenliği, hava geçirgenliği, su-geçirmezlik testleri uygulanmış ve sonuçlar üreticiler ve ilgili bilim insanlarının yararlanabileceği biçimde yorumlanmıştır. Burada ulaşılan en önemli sonuçlar sırasıyla, kumaşların kaplandığı/lamine edildiği membran/kaplamanın kalınlığının arttıkça su buharı geçirgenliğinin düştüğü, membran karakterinin (mikro-gözenekli/gözeneksiz) su buharı geçirgenliği üzerinde farklı ortam koşullarında farklı etkilerinin olduğu ve vücut ile giysi arasındaki hava boşluğunun su buharı geçirgenliğini önemli ölçüde düşürdüğüdür. Bu sonuçlar da gelecek çalışmalar açısından fikir verici nitelik taşımaktadır. In this study, it was investigated that the comfort properties of water-proof and breathable (water vapour permeable) fabrics which include a membrane or coating layer of a polymer as a composite clothing assembly.The tested samples of this study were obtained from world?s popular producers and each of them has a spesific membrane and composite structure character. These structures have a big importance on the high performance clothing which is especially worn for cold weather protection. Also they are taking place in the high value added products group.The most crucial comfort problem about multi-layered, water-proof breathable fabrics is grown out of water vapour permability. It is required that these fabrics should run the present moisture out which is produced by body when it is in the form of vapour (0,4 nm). Otherwise, especially in cold weather, the accumulated moisture in the body will get colder with the effect of cold weather and this can be result in the situation of fall down of the body temperature to under a normal level (hypothermia). The other parametres consist of other comfort parameters such as air permeability, water-proofness and thermal conductivity.In this study, it was examined that the parameters influencing on comfort charactheristics of breathable fabrics such as weather condition, the space between clothing assembly and the body, the thickness of the materials used in the production of the samples and the thickness of all composite structures. After selection and obtaining samples, water vapour permeability, air permability, water-proofness tests were applied onto the fabrics in an order and the results were interpreted in the form of knowledge which is avaliable to the related producers and scientists. The most important conclusions here are; the water vapour permeability of fabrics decrease with the increase of thickness of membrane or coating, the membrane character (microporous-solid hydrophilic) has different effect on water vapour permeability of fabrics on different weather conditions and the increase of space between clothing assembly and the body, decrease the water vapour permeability of fabrics. These conclusions provide promising knowledge for the future studies. 122

Orientadores: Eder Lima de Albuquerque, Paulo Sollero Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica Resumo: O presente trabalho tem por objetivo o cálculo de tensões em pontos no interior do domínio de placas finas anisotrópicas usando o método dos elementos de contorno. As equações integrais de contorno para deslocamentos e rotações em placas anisotrópicas são apresentadas. as derivadas de segunda ordem da equação integral de deslocamento são de senvol vidas. A partir destas equações, são calculadas as deformações e, em seguida, as tensões. Por fim são desenvolvidos procedimentos para o cálculo de critérios de falha para materiais anisotrópicos, analisando a falha em cada uma das lâminas. Exemplos são apresentados usando as rotinas desenvolvidas, cujos resultados são comparados com soluções encontradas na literatura. Os resultados obtidos pelas análises numéricas apresentam boa concordância com os resultados da literatura indicando a sua aplicabilidade em problemas reais de engenharia Abstract: The objective of the present work is the calculation of stresses in domain internal points af anisotropic thin plates using the boundary element method. Boundary integral equations for displacements and rotations in anisotropic plates are presented. Second order derivatives af the integral equation of displacement are developed. From these equations, strains and stresses are calculated. Finally procedures for the calculation of failure criteria for anisotropic matei-ials are developed, analyzing the failure in each laminae of the laminate. Examples are presented using the developed routines, wh.ose results are compared with solutions found in literature. Results for the numerical analysis present good agreement with results from the literature, indicating its applicability in real engineering problems Mestrado Mecânica dos Sólidos e Projeto Mecânico Mestre em Engenharia Mecânica

A cohesive element for shell analysis is presented. The element can be used to simulate the initiation and growth of delaminations between stacked, non-coincident layers of shell elements. The procedure to construct the element accounts for the thickness offset by applying the kinematic relations of shell deformation to transform the stiffness and internal force of a zero-thickness cohesive element such that interfacial continuity between the layers is enforced. The procedure is demonstrated by simulating the response and failure of the Mixed Mode Bending test and a skin-stiffener debond specimen. In addition, it is shown that stacks of shell elements can be used to create effective models to predict the inplane and delamination failure modes of thick components. The results indicate that simple shell models can retain many of the necessary predictive attributes of much more complex 3D models while providing the computational efficiency that is necessary for design

Orientador: Paulo Sollero Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica Resumo: Neste trabalho é desenvolvida uma formulação do método dos elementos de contorno para análise de estruturas formadas pela associação espacial de placas de laminados compósitos. Inicialmente, as formulações do método dos elementos de contorno, desenvolvida para pro­blemas de elasticidade plana e de flexão em placas finas para materiais anisotrópicos, são as­sociadas obtendo-se uma estrutura plana, denominada macro-elemento. Um macro-elemento contém simultaneamente os estados de flexão em placas finas e extensão (chapa) e possui quatro graus de liberdade por nó, sendo eles: deslocamento normal, tangencial e transver­sal e rotação normal. O modelo final assume uma associação desses macro-elementos no espaço. Cada macro-elemento é tratado como uma sub-região do MEC. As equações de cada sub-região, após as transformações de coordenadas, são acopladas através de equações de equilíbrio e compatibilidade. O tratamento numérico é feito através do método dos elemen­tos de contorno usando elementos constantes e quadráticos. Com o objetivo de validar a formulação desenvolvida, vários exemplos numéricos são analisados, os resultados obtidos são comparados com resultados analíticos e numéricos disponíveis na literatura Abstract: In this work a boundary element formulation is developed for the analysis of structures formed by three-dimensional association of symmetric laminated composite plates. Initially, the boundary element formulations developed for plane elasticity anisotropic problems and bending of anisotropic thin plate problems are associated in one plane structure with four degrees of freedom per node given by normal, tangential and transverse displacements and normal rotations. Then, the formulation is extended in order to allow the plane assembling of these structures. In the two-dimensional formulation, each plane element is defined as macro­element containing out-of-plane (bending) and in plane (stretching) degrees of freedom. The final system is obtained by assuming each individual plane structural element as a sub-­domain. After the necessary transformation of these equations, they can be combined in order to take into account displacement compatibilities and traction equilibrium conditions. The numerical treatment is carried out by the direct boundary element method. Numerical examples are presented and their results are compared to results available in literature Doutorado Mecânica dos Sólidos e Projeto Mecânico Mestre em Engenharia Mecânica

The goal of the work was to investigate the rheological properties of laminated leather and predict the relaxation behaviour in order to select and substantiate the shaping regime.

The goal of the work was to investigate the rheological properties of laminated leather and predict the relaxation behaviour in order to select and substantiate the shaping regime.

The objective of this study was to develop an analytical model of the basic hierarchical structure of the human bone. The model computed the stiffness of composite collagen fibers comprised of collagen fibrils and hydroxyapatite mineral crystals. Next, the stiffness of the concentric lamella was computed utilizing the stiffness of the collagen fibers and layer information. Finally, the effective stiffness of the bone was estimated. In order to determine the stiffness of the collagen fiber, a three-dimensional finite element model was developed and a simple analytical model was derived. The simple analytical model was validated using the finite element results. The lamination theory of unidirectional fibrous composites was used to calculate the stiffness of the lamella and eventually the bone stiffness. A series of parametric studies were conducted to understand what parameter(s) affected the stiffness of the bone most significantly. This information will be useful when an artificial bone structure is designed. http://archive.org/details/finiteelementnal109451123 Lieutenant, United States Navy Approved for public release; distribution is unlimited.

Edge delamination in fiber-reinforced composite laminates has been asignificant structural reliability concern. This particular laminate failure mode is caused by the high interlaminar stresses concentrated near the free edges. Due to the complex fiber/matrix microstructure of laminates, an accurate evaluation of these stresses and determining their exact role in laminate failure has been difficult. Traditional approaches to this problem have been based on the "effective-ply" theory in which the plies in the laminate are represented by an elastic homogenized medium. One result of this theory is the presence of stress singularities at bi- material interfaces near the free edge. These stress singularities are thought to be possible causes for edge lamination. In this research, two key issues in the free edge delamination problem are addressed: 1) to identify the physical sources for delamination, and 2) to establish a physical criterion for the onset and growth of delamination. For the first issue, a rigorous numerical stress ana lysis method is devised to accurately determine the full field stress solution, including the stress singularity. Key lamination parameters known to influence the delamination are included in the analysis. The analytical results show that delamination occurs at the largest sized interlaminar stress concentration zone, or zone of dominance (ZOD). The ZOD is shown to be more sensitive to the lamination parameters than the edge singularity is. For the second issue, the "effective flaw concept" is used to model delamination within the confines of linear elastic fracture mechanics. In this concept, an edge flaw is introduced as a starter crack inside the ZOD, and the growth of the flaw is simulated using finite element methods. Good agreement between the simulated results and experiments is achieved provided that the effective flaw is sufficiently large. However, because the crack growth simulation is performed on the "effectiveply", justification of the effective flaw at this point is heuristic. An effort is then made to recover the stress field at the fiber/matrix level near the free edges. Comparisons are made between the macro and micro-stress fields, in hope to provide a rational connection to the effective flaw of the macro-analysis.

Composite homogenization is a modeling concept that allows the description of heterogeneous materials by constitutively equivalent, homogeneous ones. The concept is universally applied to fibrous composites, resulting in many modeling approaches. But, by homogenization, the composite is voided of its physical microstructure; elements that may affect failure mechanisms physically are also voided. This fact often leads to difficulties in failure theories formulated at the homogenized material scale. De-homogenization is a reverse scheme in that the microstructure is restored, albeit locally, back in the homogenized composite. Clearly, this is done after composite homogenization and field analysis of composite structures under global loading; so the micro fields in the desired locations with restored microstructure can be recovered. The recovered micro fields may then provide the needed information for some failure theories to be formulated at the composite micro scale instead. This thesis presents a unified modeling approach for homogenization (forward) and de-homogenization (backward), applicable to unidirectional composite systems. Emphasis is placed on the uniqueness between the forward and the backward modeling processes; so the desired micro fields are truly recovered within the confines of mechanics. Micro fields in several laminates made of the UD systems are recovered; key effects that influence failure mechanisms therein are studied. An inter-scale failure theory that describes matrix cracking in laminates is then formulated, being based on the recovered micro-fields. Laminate matrix cracking in several well-documented experimental studies are simulated using the inter-scale theory. The simulation captures the major cracking characteristics that are otherwise excluded in failure theories derived at the homogenized composite scale. The general concept of homogenization/de-homogenization is applicable to all composite systems, where responses from micro-macro-global interactions are to be physically described. The approach taken in the formulation of the inter-scale theory serves as an example of both conceptual and practical importance.

ŞEKİLLENDİRİLMİŞ LAMİNE AHŞAPTAN KOLTUK MODELLEMESİ VE YORULMA PERFORMANSININ BELİRLENMESİ (YÜKSEK LİSANS TEZİ) Ayfer Yılmaz GAZİ ÜNİVERSİTESİ FEN BİLİMLERİ ENSTİTÜSÜ Eylül 2002 ÖZET Bu çalışma, laminasyon yöntemiyle bir koltuk modellemesinin ortaya konulmasını ve bu koltuğu oluşturan kavisli lamine ahşap elemanların yorulma direncinin belirlenmesini amaçlamıştır. Bu amaçla; 7 kattan oluşan deney numunelerinin hazırlanmasında asıl ağaç türü olarak Doğu kayını, Sapsız meşe, kestane ve kavak kullanılmıştır. Yalnız burada kavak, lamine ahşap elemanı oluşturan asıl ağaç türü olarak değil, kayın, meşe ve kestane papellerinin arasına özgül ağırlığı düşürmek için dolgu maddesi olarak kullanılmışlar. Kaplamaları yapıştırmak için ise PVA tutkalı kullanılmıştır. Deney sonuçlarına göre; sadece yükleme süresinin deformasyonda etkili olduğu belirlenmiştir. Deney numuneleri 80 kg yük ile yüklenmiştir. En yüksek deformasyon 60 dakika süre ile yapılan yüklemede gerçekleşmiştir. Yük kaldırıldıktan 60 dakika sonra çok az kalıcı deformasyon olduğu gözlenmiştir. Bilim Kodu : 225.12.01 Anahtar Kelimeler : Mobilya, lamine ahşap, bükme mobilya, kayın, meşe, kestane, yorulma direnci. Sayfa Adedi : 60 Tez Yöneticisi : Doç.Dr.Mustafa Altınok u MAKING A MODEL OF CHAIR FROM SHAPING LAMINATED WOOD MATERIAL AND DEDETERMİNG OF FATİGUE STRENGTH (M.Sc Thesis) Ayfer Yılmaz GAZİ UNIVERSITY INSTITUTE OF SCBENCE AND TECNOLOGY September 2002 ABSTRACT In this study, it has been determined fatigue strength of laminated wood material and made a model of armchair. For this purpose; it was tested to determine the fatigue strength of experimentals prepared from 7 layers materials, which are used beech (Fagus orientalis ), oak (Quercus petrea) and chestnut. Pouhis nigra was just used as a fill material Experimentals was bonded PVA. Experimentals was loaded with 80 kg for fatigue strength test At the result of experimentals, it has been obtained effects of loading time at the deformation. It has been the highest deformation in 60 minutes. After 60 minutes from taking of load, it has been obtained a little permanent deformation. Science Code : 225.12.01 Key Words : Furniture, Laminated Wood, Bending of Wood, Fagus, Oak, Chestnut, Fatigue strength. Number of Page :60 Advisor : DoçJDr.Mustafa Altinok *SSSSSSS.^s«* 60

LÂMİNE MASİF AĞAÇ MALZEMELERİN TEKNOLOJİK ÖZELLİKLERİ ve AĞAÇ İŞLERİ ENDÜSTRİSİNDE KULLANIM İMKÂNLARI (Doktora Tezi) Hakan KESKİN GAZİ ÜNİVERSİTESİ FEN BİLİMLERİ ENSTİTÜSÜ EYLÜL 2001 ÖZET Bu çalışmada, ülkemiz ağaç işleri endüstrisinde yeni kullanılmaya başla nan lâmine masif ağaç malzemelerin teknolojik özelliklerinin belirlenmesi amaçlanmıştır. Bu amaçla, ülkemizde yaygın olarak kullanılan Toros sediri (Cedrus libani A. Rich.), sarıçam (Pinus sylvestris L.), Doğu kayını (Fagus orientalis Lipskyj ve sapsız meşe (Quercus petrea L.) odunlarından dört katmanlı olarak ha zırlanan lâmine masif ağaç malzemeler, sertleştirici (Dorus R.397) ilâve edilerek güçlendirilmiş Polivinilasetat (PVAc) D4 tipi tutkal ile lâmine edi len örnekler kullanılmıştır. Deneylerde, etki faktörleri (ağaç türü, sertleştirici oranı, bekletme ortamı, işlem türü) dikkate alınarak toplam 2064 adet örnek üzerinde, yoğunluk, termik genleşme katsayısı, ısı iletkenlik katsayısı, çalışma miktarı, basınç, eğilme, makaslama, çekme-yarılma ve yapışma dirençleri ile eğilmede elâstiklik modülü belirlenmiştir. Deneyler sonunda, lâmine edilmiş ağaç malzemelerin teknolojik özelliklerinin türlerini temsil eden masif ağaç malzemelerden daha üstün oldukları tespit edilmiştir. Bilim Kodu : 6001020 Anahtar Kelimeler : Lâminasyon, Toros sediri, sarıçam, Doğu kayını, sapsız meşe, polivinilasetat Sayfa Adedi : 150 Tez Yöneticisi : Prof. Dr. Yalçın ÖRS 11 TECHNICAL PROPERTIES OF LAMINATED WOOD MATERIALS and POSSIBILITIES OF USING THEM IN WOODWORKING INDUSTRY (Ph.D. Thesis) Hakan KESKİN GAZI UNIVERSITY INSTITUTE OF SCIENCE AND TECHNOLOGY SEPTEMBER 2001 ABSTRACT In this study, it is aimed to ascertain and determine the technical properties of laminated wood materials which people have just started to use them in the woodworking industry in our country. For this purpose, the laminated wood materials prepared in the form of four layers from Cedrus libani A. Rich., Pinus sylvestrish., Fagus orientalis Lipsky and Quercus petrea L. woods which are used commonly in Turkey have been glued by using PVAc-D4 type adhesive which were strengthened by adding the hardener (Dorus R.397). In the experiments, by taking the influence factors (type of wood, rate of hardening material, environment for it to wait, type of procedure) into con sideration, the density, the thermic swelling coefficient, thermal conductivity coefficiend, working amount, compression strengths, cleavage and bursting, sticking strengths and modulus of elasticity were determined with using totaly 2064 samples. At the end of the experiments, it has been proven that the technological properties of the laminated wood materials have more superior values than the solid wood materials which were representing their kinds. Science code : 6001020 Key words : Lamination, Cedrus libani A.Rich, Pinus sylvestris L., Fagus orientalis Lipsky, Quercus petrea L., polyvinylacetat Page number : 150 Adviser : Prof. Dr. Yalçın ÖRS 150

Bu çalışmada, emprenye edilmiş ağaç malzemeden üretilen 5 ve 8 katmanlı lamine ağaç malzemenin teknolojik özellikleri araştırılmıştır. Lamine elemanların dış katmanlarında Doğu kayını (Fagus ovientalis Lipsky) ve sarıçam (Pinus sylvestris L.), orta katmanda ise kavak (Populus nigra.) odunlarından üretilen papel kaplamalar kullanılmıştır. Bu amaçla, tanalith-C 3310. boraks, borik asit, boraks+borik asit ve di-amoniumpfosate kimyasalları yanmayı geciktirici emprenye maddesi olarak kullanılmıştır. Bunun için örnekler. ASTM-D 1413-76 esaslarına göre 60 dakika süreyle 760 mm Hg~'`ya eşdeğer ön vakum, 60 dakika süreyle 2 atmosfer basıncında çözelti içerisinde emprenye edildikten sonra fenol formaldehid ve melamin formaldehid tutkallan ile yüksek sıcaklıkta preslenerek lamine ağaç malzemeler elde edilmiştir. Örneklerin, eğilme direnci, elastiklik modülü, yoğunlukları, hacimsel genişleme, yapışma direnci, basınç direnci ve yanma değerleri belirlenmiştir. Deneyler sonunda; borik asit ve tanalith-C 3310 lamine ağaç malzemelerin teknolojik özelliklerini olumsuz yönde etkilerken diğer emprenye maddeleri olumlu etkiler göstermiştir.Anahtar Kelimeler : Laminasyon, sarıçam, Doğu kayını, boraks, borik asit. diamony um fosfat, tanalith-C 3310. fenol formaldehid. melamin formaldehid. In this study, the technological properties of laminated wood materials (LWM). prepared from Fagus orientalis Lipsky and Pinus sylvestris L. having five and eight ply, impregnated with tanalith-C 3310, borax, boric acid, borax+boric acid and di-ammonium phosphate chemicals were examined. Fagus orientalis Lipsky and Pinus sylvestris L. woods were used outer ply and Populus nigra used for core ply in LVL. For this purpose; before the gluing process, veneers were processed with impregnation chemicals according to the procedure of ASTM-D 1413-76 standards during 60 minutes with 760 mm Hg~l pre-vacuum then, 60 minutes 2 atmospheric pressure. And then, veneers were bonded with phenol formaldehyde and melamin formaldehyde adhesives and LVL was obtained. In the experiments, bending strength, modulus of elasticity, density, dimensional changes, bonding strengths, compression strengths and combustion properties have been determined. In conclusion, it was proven that boric acid and tanalith-C 3310 gave the negative effect and the other chemicals showed the positive effect for LWM.Key words :Lamination, Fagus orientalis Lipsky, Pinus sylvestris L., borax, boric acid, di-ammonium phosphate, tanalith-C 3310, phenol formaldehyde, melamin formaldehyde. 108

öz `Lamine Ağaç Malzemeden Pencere Profili Üretimi Ve Bazi Kalite Özelliklerinin Belirlenmesi` Bu çalışmada; Ülkemiz orman varlığı içinde önemli bir yer tutan ve doğrama endüstrisinde yaygın olarak kullanılan Sarıçam ile odun yapısı gereği doğrama üretiminde daha az kullanım bulan Kızılcam odunundan, rutubete dayanıklı Üre Formaldehit ve PVAc tutkallan kullanılarak, lamine pencere profilleri üretilmiştir. Lamine malzeme üretiminde, üretimin ve kalite kontrolünün, hazırlanacak olan ve bir örneği Tablo 4'de verilmiş bir kontrol planı çerçevesinde yürütülmesinin gereği ve önemi belirlenmiştir. Daha sonra, bu örnek profillerin pencereler için önemli olabilecek fiziksel ve mekanik özellikleri incelenmiş ve bu özellikler üzerine laminasyondaki; tutkal farklılığı, lamel kalınlıkları ve yıllık halka düzenlemelerinin etkisi ortaya konulmuştur. Son olarak, elde edilen bulgular ve sonuçlar çerçevesinde, doğrama endüstrisine yönelik olmak üzere önerilerde bulunulmuştur. ABSTRACT `The Production of Laminated Window Profiles and The Determination Some of Its Quality Properties` In this study, laminated window profiles were produced by using Pinus sylvestris which has an important place in the forest resource of Turkey and used extensively in window - framing industry in Turkey; and Pinus brutia T. which is not used extensively due to its wood structure ; and Urea Formaldehyde and PVAc glues which are resistant to moisture. Furthermore, it was indicated that the production and quality control in the laminated wood manufacturing should be carried out by taking account of a control scheme (Table 4 in the text). Afterwards, the physical - mechanical properties of the laminated window profiles were investigated and the effects of qlue type, layer thickness and annual ring structure on the lamination were explained. At last, some proposals related to window - framing industry were given by taking account of the result, obtained. öz `Lamine Ağaç Malzemeden Pencere Profili Üretimi Ve Bazi Kalite Özelliklerinin Belirlenmesi` Bu çalışmada; Ülkemiz orman varlığı içinde önemli bir yer tutan ve doğrama endüstrisinde yaygın olarak kullanılan Sarıçam ile odun yapısı gereği doğrama üretiminde daha az kullanım bulan Kızılcam odunundan, rutubete dayanıklı Üre Formaldehit ve PVAc tutkallan kullanılarak, lamine pencere profilleri üretilmiştir. Lamine malzeme üretiminde, üretimin ve kalite kontrolünün, hazırlanacak olan ve bir örneği Tablo 4'de verilmiş bir kontrol planı çerçevesinde yürütülmesinin gereği ve önemi belirlenmiştir. Daha sonra, bu örnek profillerin pencereler için önemli olabilecek fiziksel ve mekanik özellikleri incelenmiş ve bu özellikler üzerine laminasyondaki; tutkal farklılığı, lamel kalınlıkları ve yıllık halka düzenlemelerinin etkisi ortaya konulmuştur. Son olarak, elde edilen bulgular ve sonuçlar çerçevesinde, doğrama endüstrisine yönelik olmak üzere önerilerde bulunulmuştur. ABSTRACT `The Production of Laminated Window Profiles and The Determination Some of Its Quality Properties` In this study, laminated window profiles were produced by using Pinus sylvestris which has an important place in the forest resource of Turkey and used extensively in window - framing industry in Turkey; and Pinus brutia T. which is not used extensively due to its wood structure ; and Urea Formaldehyde and PVAc glues which are resistant to moisture. Furthermore, it was indicated that the production and quality control in the laminated wood manufacturing should be carried out by taking account of a control scheme (Table 4 in the text). Afterwards, the physical - mechanical properties of the laminated window profiles were investigated and the effects of qlue type, layer thickness and annual ring structure on the lamination were explained. At last, some proposals related to window - framing industry were given by taking account of the result, obtained. 204

This thesis deals with three inter-related topics. The first topic is concerned with the solution of a cracked transversely isotropic—orthotrOpic composite laminate of finite thickness. The transversely isotropic sublaminate which is sandwiched between orthotropic outer sublarninates contains a central crack or an array of periodically distributed cracks which are perpendicular to the interfaces between the two media. When the crack is wholly within the sublaminate, solutions are obtained for the stress intensity factors and the crack-induced interfacial stresses in three loading modes. When the crack tips touch the interfaces, the stress singularities are no longer the usual square-root type but are determined by the mechanical properties of the media. In this case, solutions are obtained for stress singularities and the corresponding stress intensity factors. The degenerate case when the outer sublarninates are also isotropic but dissimilar from the central sublaminate is also solved. The second topic concerns the application of the above fracture mechanics solutions to crack problems of laminates composed of unidirectional fibre-reinforced composites. In view of the fact that unidirectional fibre-reinforced composites are prone to transverse cracking and that laminates made from unidirectional plies are prone to delamination, a cracked [(il9),,2 /(900)n1 ]s symmetric laminate is studied with a view to examining the mutual constraining effect of plies on transverse cracking and the role of transverse cracks in causing delamination. The fracture mechanics framework is used to reveal the mechanisms behind the enhancement of the socalled in situ strengths of unidirectional laminae in multidirectional laminates. When the tips of a transverse crack touch the interfaces, the effect of the properties of the constraining sublarninates on the stress singularities and stress intensities at the tips of the crack is investigated. The third topic is concerned with two types of optimum strength design of composites laminates. First, for a fibre-reinforced antisymmetric [(:l:0°)n2 / (90°)n1 / (2120),,2] angle-ply laminate, the design variables of the laminate, viz. the ply angle 0 and relative ply thickness, are chosen in such a way as to minimize the stress intensity factor at the crack tip in the (900),“ lamina without exceeding the interfacial maximum principal tensile stress. Secondly, based upon the extensive fracture mechanics analysis (from topics one and two), a set of in situ strength parameters for unidirectional laminae in a multidirectional laminate is proposed. The in situ strength parameters take into account the influence of adjacent laminae and thickness of a particular lamina upon its transverse tensile and in-plane shear strengths when it is used in a multidirectional laminate. These strength parameters are then employed to calculate a stress norm which determines how close the stress state in the lamina is to its failure state. The stress norm is incorporated into the formalism of an optimization problem in order to enhance the load bearing capacity of multidirectional laminates.