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Implant failures and postoperative complications are often associated to the bone drilling. Estimation and control of drilling parameters are critical to prevent mechanical damage to the bone tissues. For better performance of the drilling procedures, it is essential to understand the mechanical behaviour of bones that leads to their failures and consequently to improve the cutting conditions. This paper investigates the effect of drill speed and feed-rate on mechanical damage during drilling of solid rigid foam materials, with similar mechanical properties to the human bone. Experimental tests were conducted on biomechanical blocks instrumented with strain gauges to assess the drill speed and feed-rate influence. A three-dimensional dynamic finite element model to predict the bone stresses, as a function of drilling conditions, drill geometry and bone model, was developed. These simulations incorporate the dynamic characteristics involved in the drilling process. The element removal scheme is taken into account and allows advanced simulations of tool penetration and material removal. Experimental and numerical results show that generated stresses in the material tend to increase with tool penetration. Higher drill speed leads to an increase of von-Mises stresses and strains in the solid rigid foams. However, when the feed-rate is higher, the stresses and strains are lower. The numerical normal stresses and strains are found to be in good agreement with experimental results. The models could be an accurate analysis tool to simulate the stresses distribution in the bone during the drilling process.

The main objective of this paper is to develop a numerical model for thermal analysis of wooden slabs with cavities, when subjected to the fire action. The temperature profiles, the charring depth layer and the charring rate will be determined using the finite element method with ANSYS program. The numerical calculation of the temperature profiles will be obtained through a transient and a non-linear thermal analysis, where the material properties are temperature dependent. These properties were established in accordance with the referenced data and numerically calibrated. Two different models of wooden slabs with cavities were studied. One model characterizes a wood slab with void cavities and other with insulation material. To characterize the fire resistance in wooden slabs with insulated cavities or void cavities, different typical curves of charring depth layer will be obtained. A numerical procedure is proposed to identify the heating action into the slab cavities. All numerical results permit the verification of the fire safety in wooden slabs with cavities.

The main goal of this paper is to develop a numerical model to assess the fire behaviour of cellular wood slabs with different drillings. A transient thermal analysis with nonlinear material behaviour will be solved with ANSYS program. The presented numerical model is based on a constructive solution proposed by Frangi and Fontana. The numerical results obtained will be compared with the experimental results from the reference. The developed numerical model allows future studies and simultaneously characterizes the effect of perforations in wooden slabs to minimize the fire risk. The numerical model can easily be adjusted for other constructive solutions, to facilitate the verification of safety in case of fire, in buildings with several wood floors and slabs assemblies.

A displacement formulation for cylindrical shells subjected to radial loads is presented. Static loads are applied to straight thin pipes using a variational method and results are compared both to finite element analysis and a shell element from Ansys program. The formulation includes a combination of trigonometric functions in two variables, longitudinal and circumferential direction. Then a system of differential equations is solved for two different load cases and the vertical displacement is obtained in the points where the load is applied.

An experimental program was defined aiming to evaluate the dimensional stability of hardwood and softwood species. The maritime pine softwood (Pinus pinaster) and the ash hardwood of the North-east region of Portugal are analysed. A group of thirty specimens were made for each species of wood. The experimental procedure has been conducted according to NP EN 614 and NP EN 615. For each wood species, one half of the specimens were previously dried while the other one half was prior saturated. Two main variables were studied in normal environmental conditions: mass and dimensional variation. Tests were conducted at 20ºC environment temperature and 60% of relative humidity. Measurements were taken allowing to quantify the dimensional variation suffered during the dry/saturation process for both species. The properties that define the behaviour of wood against temperature and moisture actions are assessed in this work. Hygroscopicity and shrinkage are given special attention.

Com este trabalho pretende-se obter estimativas do risco, associado a fracturas do tecido ósseo, função de alguma patologia, que se possa generalizar ou não para qualquer paciente, com base em determinados factores, nomeadamente, idade, estilo de vida, terapêutica associada, em função de dados clínicos obtidos em pacientes do género feminino na zona Litoral Norte de Portugal. No último triénio de 2010 foram avaliadas 125 pacientes na clínica Dr. Krug de Noronha, Radiologia/Imagem, com idades compreendidas entre os 30 e 85 anos para esse efeito. Foram obtidos e avaliados os exames densitométricos em relação à frequência de osteoporose ou osteopenia do colo do fémur e da coluna lombar destas pacientes. Simultaneamente foi elaborado um inquérito às pacientes com informações adicionais, dados pessoais, antropométricos, ginecológicos, considerando ainda a tipologia de factores de risco associados à osteoporose. Com base na amostra obtida serão apresentados diferentes gráficos por faixa etária para uma avaliação e discussão detalhada de cada factor de risco prevalente.

The main objective of this study was to investigate if there is a relation between the cortical bone thickness of human mandibles, with age and patient gender. In this work, the measure of the cortical bone thickness was obtained using different medical images. Different human mandibles were obtained, with high resolution, through computed tomography. The cortical thickness was measured using image processing software (Sante DICOM Viewer FREE, Santesoft). The three dimensional visualization of the medical images was obtained using InVesalius 3.0 (FREE Beta 2 Software, C. T. I. Renato Archer). An initial work with this purpose was produced by [Fonseca, et al 2010] using other software. A total of eight medical images were analysed in two different groups. One group was characterized with four female mandibles, from different ages (26-79 years old). Other group with four male mandibles has similar age (42-57 years old). The cortical thickness value was obtained for each studied case. A comparison between gender patients was obtained. Conclusions about the cortical bone thickness of the mandible affected by tooth extraction, age and gender patient will be produced. The use of this type of information could be useful for complementary diagnostic information and clinical treatment planning.

Um dos objectivos deste trabalho é avaliar estruturalmente duas espécies de madeira, calculando a sua resistência ao fogo para diferentes cenários de incêndio e determinando a redução da sua secção recta. Será utilizado o método dos elementos finitos através do programa ANSYS para a determinação da camada e da velocidade de carbonização, nas diferentes análises em estudo. O cálculo do perfil de temperaturas, nas diferentes secções em estudo, será obtido em regime transiente. Serão consideradas as propriedades térmicas não lineares do material, dependentes da evolução da temperatura, de acordo com as regras estabelecidas no [Eurocódigo 5, 2003]. O outro objectivo deste trabalho é a determinação de estados de tensão em elementos do tipo viga, sob influência da redução da secção recta. Neste tipo de estudo, será dada particular importância às propriedades ortotrópicas da madeira, função da temperatura, a utilizar no modelo de elementos finitos. Este trabalho será organizado de forma a contribuir com regras práticas de projecto, na utilização deste tipo de elementos estruturais, através da apresentação de gráficos da resistência ao fogo e de uma metodologia de cálculo simplificada, na determinação do campo de tensões em vigas submetidas a acções térmicas e mecânicas.

The bone mass reduction and the deterioration of the tissue micron-architecture lead to a bigger fragility of the bone and to the consequent increase of the fracture risk. For this fact, it is considered excellent the quantification of the mass density and the verification of its influence in the bone resistance assessment. The apparent density is defined as the density without fluid influence, being the effective density at that includes the marrow mass, essentially fluid. This measurement is made through the use of a gray scale values on the medical image in study. The values in Hounsfield units are determined, being this scale later converted into measure of the bone density. With this measure an exponential relation will be used allowing calculate the biomechanics properties dependence for cortical and trabecular bone. With this work it is intended to assessment the susceptible weak zones, for a human femur with 70 years old, using the finite element method through ANSYS® program. The main objective is obtaining the stresses distributions, using different values of bone density and their relation with exponential laws for isotropic and orthotropic materials properties.

A articulação do joelho é um sistema complexo e de grande importância no esqueleto humano. Para além das funções de transferência de forças, permite a estabilidade e a mobilidade do membro inferior. A articulação do joelho é essencial para actividades como andar, subir escadas ou ficar de pé. É a principal articulação nas actividades que envolvam desportos. As lesões da articulação do joelho são frequentes, nomeadamente em modalidades desportivas que envolvam ou não contacto, através de distensões dos ligamentos. Estas distensões ocorrem quando o pé está fixo ao solo. Um número elevado de lesões acontece ainda devido a acidentes provocados por colisões entre veículos e pessoas (Grzegorg et al, 2001). O presente trabalho tem como principal objectivo efectuar uma análise numérica do comportamento não linear do joelho humano quando submetido a impacto frontal.

A articulação do joelho é um sistema complexo e de grande importância no esqueleto humano. Para além das funções de transferência de forças, permite a estabilidade e a mobilidade do membro inferior. A articulação do joelho é essencial para actividades como andar, subir escadas ou ficar de pé. É a principal articulação nas actividades que envolvam desportos. As lesões da articulação do joelho são frequentes, nomeadamente em modalidades desportivas que envolvam ou não contacto, através de distensões dos ligamentos. Estas distensões ocorrem quando o pé está fixo ao solo. Um número elevado de lesões acontece ainda devido a acidentes provocados por colisões entre veículos e pessoas (Grzegorg et al, 2001). O presente trabalho tem como principal objectivo efectuar uma análise numérica do comportamento não linear do joelho humano quando submetido a impacto frontal.