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The use of lime-based composites reinforced with fabrics made of natural fibers, is a promising solution for the strengthening of historical masonry structures owing to its moderate mechanical strength, similar color and chemical compatibility, avoiding damage on the historical structure and contributing to crack-width control. In this study, a new lime-based composite reinforced with flax nonwoven fabrics is mechanically characterized to study its reinforcement potential in terms of strength, and stress distribution. To this end, laminate plates with lime/metakaolin matrix and four to six layers of fabric reinforcement were produced and totally carbonated in a CO2 chamber. Both the mechanical (flexural and tensile) and durability (against wet-dry cycles) properties of the composite were subsequently assessed. Furthermore, Digital Image Correlation (DIC) was carried out on tensile testing to study the stress distribution. The 6-layer composites displayed the best performance (with flexural and tensile strengths of approximately 5.3 MPa and 2.5 MPa, respectively), followed by the 5-layer and the 4-layer composites. The DIC analysis revealed a higher stress distribution in the 6-layer composites, with an increased number of cracks, although having a lower severity. As for durability, a decrease of 30–45% is observed in flexural strength, and of 6–18% in tensile strength, depending on the number of reinforcing layers. SEM analysis refers to fiber/matrix debonding as the cause of this decrease. No damage has been observed on the fiber surface, which retains its reinforcing capacity. All of the composites displayed strain-hardening behavior in both the unaged and aged conditions. Study outcomes are intended to serve as the basis for the creation of a future, compatible, reliable, and sustainable system given its potential application in the historical restoration of masonry structures, The authors wish to express their gratitude to the Spanish government’s Ministerio de Ciencia e Innovación (MCIN) and Agencia Estatal de Investigación (AEI) for the financial support provided within the scope of the RECYBUILDMAT project (PID2019–108067RB-I00MICIN/ AEI/10.13039/501100011033), and the Generalitat de Catalunya’s Agència de gestió d’Ajuts Universitaris i de Recerca (AGAUR) for the financial support provided to the TECTEX Research Group (2021 SGR 01056). The author Heura Ventura is a Serra-Húnter fellow, Postprint (published version)

Due to the recent boom in digital design for additive manufacturing and 3D printing, there has been a significantly growing interest in latticed structures for light design and improved mechanical properties. However, the focus in the literature has mostly been on compressive mechanical properties of uniformly latticed structures with little emphasis on flexural properties of latticed-beams that are functionally graded and hybridized with different lattice topologies. Therefore, this paper aims to explore the effect of lattice relative density gradation and hybridization on the specific flexural properties of prominent sheet-based triply periodic minimal surfaces (TPMS) cellular four-point loaded beams. First, the effective elastic properties of the cubic porous topologies are evaluated computationally to converge to certain sheet-based TPMS cellular structures capable of providing high flexural properties. Schwartz primitive (P) revealed high stiffness to shear loading, meanwhile, the F-Rhombic Dodecahedron (FRD) showed better resistance to uniaxial loading, and the Diamond (D) showed well-combined uniaxial and shear moduli. The selected four-point bend (4 PB) latticed-beams are functionally graded following a bilinear pattern and hybridized through the span of their length inspired by the shearing force and bending moment diagrams arising in the 4 PB beam, in view of the effective elastic properties of the TPMS topologies. The additively manufactured AlSi10Mg uniform, functionally-graded, and hybridized latticed-beams are tested in four-point bending and the results are compared with the finite element results. Both the experimental and numerical outcomes show good agreement within the elastic-plastic regime. From experimental results, it is found that functional grading and hybridization can considerably enhance the specific flexural modulus of sheetbased TPMS latticed-beams. Also, relative density gradation within the four-point bend specimens proved very essent, QC 20220608

Fused Filament Fabrication (FFF) is a popular additive manufacturing process to produce printed polymer components, whereby their strength is highly dependent on the process parameters. The raster angle and infill pattern are two key process parameters and their effects on flexural properties need further research. Therefore, the present study aimed to print test specimens with varying raster angles and infill patterns to learn their influence on the in-plane and edgewise flexural properties of acrylonitrile–butadiene–styrene (ABS) material. The results revealed that the highest in-plane and edgewise flexural moduli were obtained when printing was performed at 0 ° raster angle. In comparison, the lowest values were obtained when the printing was executed with a 90 ° raster angle. Regarding the infill pattern, the tri-hexagon pattern showed the largest in-plane modulus, and the quarter-cubic pattern exhibited the greatest edgewise flexural modulus. However, considering both the modulus and load carrying capacity, the quarter-cubic pattern showed satisfactory performance in both planes. Furthermore, scanning electron microscopy was used to investigate the failure modes, i.e., raster rupture, delamination of successive layers and void formation. The failure occurred either due to one or a combination of these modes.

This paper presents the experimental and analytical studies to investigate the effect of concentrated butt-joints on the flexural properties of laminated bamboo-timber flitch beam (BTFB, or bio-flitch beam). The experimental results reveal that the concentrated butt-joints significantly reduce the flexural strength of the BTFB. They also suggest that the failure mechanism of the BTFB with or without concentrated butt-joints are completely different but less evidence shows an obvious effect of the butt-joints on the modulus of elasticity in bending. In addition, laminated bamboo lumber with concentrated butt-joints is found to be unsuitable for structural applications. The analytical predictions are in close agreement with the experimental results that demonstrate the potentials of the proposed analytical model as a forensic investigation instrument to estimate the strength reduction of the structure, if the butt-jointed laminated bamboo was, unfortunately, used in construction. © The Author(s) 2021.

One of the most common load modes is flexure. The paper measures and models the flexural strength and modulus of a bio-polyethylene reinforced with thermos-mechanical fibers from corn stover. Moreover, the authors use modified rules of mixtures to evaluate the contribution of the reinforcements to the properties of the composite. It was found a high impact of coupling agent content on the strength of the composites, and materials with a 6% of such agent and 50% of reinforcement increased 181% the strength of the matrix, and 464% its modulus. The obtained values are noticeable higher than polypropylene and some of its composites. Micromechanics analysis shows that the effect of natural fiber reinforcement on the flexural properties of a bio-based PE is similar to the effects on a polyolefin. Thus, the use of fully bio-based composites can be proposed as a substitute for some oil-based polymers, partially bio-based materials, and their composites, Postprint (author's final draft)

This paper presents the experimental and analytical studies to investigate the effect of concentrated butt-joints on the flexural properties of laminated bamboo-timber flitch beam (BTFB, or bio-flitch beam). The experimental results reveal that the concentrated butt-joints significantly reduce the flexural strength of the BTFB. They also suggest that the failure mechanism of the BTFB with or without concentrated butt-joints are completely different but less evidence shows an obvious effect of the butt-joints on the modulus of elasticity in bending. In addition, laminated bamboo lumber with concentrated butt-joints is found to be unsuitable for structural applications. The analytical predictions are in close agreement with the experimental results that demonstrate the potentials of the proposed analytical model as a forensic investigation instrument to estimate the strength reduction of the structure, if the butt-jointed laminated bamboo was, unfortunately, used in construction. © The Author(s) 2021.

This paper presents the versatility of coconut fibersand its applications in different branches of engineering. Inpresent days, automobile industries are rapidly increased. All the automobile industries are in the process of supplying the vehicles at low cost. The major cost of the automobile components is its body parts. As per the any automobile industries concentrate with automotive components end life is very important factor in the design of the automotive. So,everybody is concentrating on new materials which will be strong enough, less weight, recyclable with reduced cost. Hence all the researchers are concentrated on the composite materials which have all the above properties. Hence the present work is concentrated on coconut coir fibre.

This paper presents the versatility of coconut fibersand its applications in different branches of engineering. Inpresent days, automobile industries are rapidly increased. All the automobile industries are in the process of supplying the vehicles at low cost. The major cost of the automobile components is its body parts. As per the any automobile industries concentrate with automotive components end life is very important factor in the design of the automotive. So,everybody is concentrating on new materials which will be strong enough, less weight, recyclable with reduced cost. Hence all the researchers are concentrated on the composite materials which have all the above properties. Hence the present work is concentrated on coconut coir fibre.

This paper presents the versatility of coconut fibersand its applications in different branches of engineering. Inpresent days, automobile industries are rapidly increased. All the automobile industries are in the process of supplying the vehicles at low cost. The major cost of the automobile components is its body parts. As per the any automobile industries concentrate with automotive components end life is very important factor in the design of the automotive. So,everybody is concentrating on new materials which will be strong enough, less weight, recyclable with reduced cost. Hence all the researchers are concentrated on the composite materials which have all the above properties. Hence the present work is concentrated on coconut coir fibre.

This paper presents the versatility of coconut fibersand its applications in different branches of engineering. Inpresent days, automobile industries are rapidly increased. All the automobile industries are in the process of supplying the vehicles at low cost. The major cost of the automobile components is its body parts. As per the any automobile industries concentrate with automotive components end life is very important factor in the design of the automotive. So,everybody is concentrating on new materials which will be strong enough, less weight, recyclable with reduced cost. Hence all the researchers are concentrated on the composite materials which have all the above properties. Hence the present work is concentrated on coconut coir fibre.

This paper presents the versatility of coconut fibersand its applications in different branches of engineering. Inpresent days, automobile industries are rapidly increased. All the automobile industries are in the process of supplying the vehicles at low cost. The major cost of the automobile components is its body parts. As per the any automobile industries concentrate with automotive components end life is very important factor in the design of the automotive. So,everybody is concentrating on new materials which will be strong enough, less weight, recyclable with reduced cost. Hence all the researchers are concentrated on the composite materials which have all the above properties. Hence the present work is concentrated on coconut coir fibre.

This paper presents the versatility of coconut fibersand its applications in different branches of engineering. Inpresent days, automobile industries are rapidly increased. All the automobile industries are in the process of supplying the vehicles at low cost. The major cost of the automobile components is its body parts. As per the any automobile industries concentrate with automotive components end life is very important factor in the design of the automotive. So,everybody is concentrating on new materials which will be strong enough, less weight, recyclable with reduced cost. Hence all the researchers are concentrated on the composite materials which have all the above properties. Hence the present work is concentrated on coconut coir fibre.

This paper presents the versatility of coconut fibersand its applications in different branches of engineering. Inpresent days, automobile industries are rapidly increased. All the automobile industries are in the process of supplying the vehicles at low cost. The major cost of the automobile components is its body parts. As per the any automobile industries concentrate with automotive components end life is very important factor in the design of the automotive. So,everybody is concentrating on new materials which will be strong enough, less weight, recyclable with reduced cost. Hence all the researchers are concentrated on the composite materials which have all the above properties. Hence the present work is concentrated on coconut coir fibre.

This paper presents the experimental and analytical studies to investigate the effect of concentrated butt-joints on the flexural properties of laminated bamboo-timber flitch beam (BTFB, or bio-flitch beam). The experimental results reveal that the concentrated butt-joints significantly reduce the flexural strength of the BTFB. They also suggest that the failure mechanism of the BTFB with or without concentrated butt-joints are completely different but less evidence shows an obvious effect of the butt-joints on the modulus of elasticity in bending. In addition, laminated bamboo lumber with concentrated butt-joints is found to be unsuitable for structural applications. The analytical predictions are in close agreement with the experimental results that demonstrate the potentials of the proposed analytical model as a forensic investigation instrument to estimate the strength reduction of the structure, if the butt-jointed laminated bamboo was, unfortunately, used in construction. © The Author(s) 2021.

Near infrared spectroscopy is non-invasive and may be applied as a rapid and cost effective technique for assessment of quality parameters of timber. Near infrared spectra of Tectona grandis (teak) wood samples of were collected before measuring physical (density, equilibrium moisture content) and strength (flexural and compressive) properties using conventional methods. Partial least squares regression was used to develop calibration models between measured wood properties and near infrared data. The best near infrared spectra pre-processing methods differed by property. Linear calibration models with high R², low error and high ratio of performance to deviation values were observed from partial least squares analysis for different wood properties. These linear models may be applied for rapid and precise estimation of the properties examined in testing and evaluation procedures for commercially valuable teak wood

Near infrared spectroscopy is non-invasive and may be applied as a rapid and cost effective technique for assessment of quality parameters of timber. Near infrared spectra of Tectona grandis (teak) wood samples of were collected before measuring physical (density, equilibrium moisture content) and strength (flexural and compressive) properties using conventional methods. Partial least squares regression was used to develop calibration models between measured wood properties and near infrared data. The best near infrared spectra pre-processing methods differed by property. Linear calibration models with high R², low error and high ratio of performance to deviation values were observed from partial least squares analysis for different wood properties. These linear models may be applied for rapid and precise estimation of the properties examined in testing and evaluation procedures for commercially valuable teak wood

This paper presents the versatility of coconut fibersand its applications in different branches of engineering. Inpresent days, automobile industries are rapidly increased. All the automobile industries are in the process of supplying the vehicles at low cost. The major cost of the automobile components is its body parts. As per the any automobile industries concentrate with automotive components end life is very important factor in the design of the automotive. So,everybody is concentrating on new materials which will be strong enough, less weight, recyclable with reduced cost. Hence all the researchers are concentrated on the composite materials which have all the above properties. Hence the present work is concentrated on coconut coir fibre.

Near infrared spectroscopy is non-invasive and may be applied as a rapid and cost effective technique for assessment of quality parameters of timber. Near infrared spectra of Tectona grandis (teak) wood samples of were collected before measuring physical (density, equilibrium moisture content) and strength (flexural and compressive) properties using conventional methods. Partial least squares regression was used to develop calibration models between measured wood properties and near infrared data. The best near infrared spectra pre-processing methods differed by property. Linear calibration models with high R², low error and high ratio of performance to deviation values were observed from partial least squares analysis for different wood properties. These linear models may be applied for rapid and precise estimation of the properties examined in testing and evaluation procedures for commercially valuable teak wood

Purpose: The objective of this study was to evaluate the physical and mechanical properties of a short fiber-reinforced resin composite: everX-Posterior and compare it with two bulk-fill composites, namely, Filtek Bulk-fill and Beautifil-Bulk, which are intended for large posterior restorations. Methods: Investigated properties were flexural strength, flexural modulus, surface roughness, volumetric shrinkage and depth of cure. Scanning electron microscopy images of each specimen after the flexural test were used for cross-sectional comparison. Results were analyzed using ANOVA following Tukey post-hoc test. Results: Flexural strength of everX-Posterior was comparable with two other resin composites, showing higher flexural modulus. EverX-Posterior showed the highest surface roughness after polishing and the lowest volumetric shrinkage (2.29%) among all composites used in this study. Data also showed that the everX-Posterior depth of cure was 4.24 mm, which was the highest among the three groups. Conclusion: Based on the results of this study, it was concluded that everX-Posterior as a short fiber-reinforced composite showed improvements and satisfactory performance in mechanical and physical properties, which make it a reliable base material candidate for large posterior restorations., Journal of Oral Science, 63(2), pp. 148-151; 2021

Near infrared spectroscopy is non-invasive and may be applied as a rapid and cost effective technique for assessment of quality parameters of timber. Near infrared spectra of Tectona grandis (teak) wood samples of were collected before measuring physical (density, equilibrium moisture content) and strength (flexural and compressive) properties using conventional methods. Partial least squares regression was used to develop calibration models between measured wood properties and near infrared data. The best near infrared spectra pre-processing methods differed by property. Linear calibration models with high R², low error and high ratio of performance to deviation values were observed from partial least squares analysis for different wood properties. These linear models may be applied for rapid and precise estimation of the properties examined in testing and evaluation procedures for commercially valuable teak wood

Purpose: The aim of this comparative in vitro study was to assess the bond strength and mechanical failure of carbon-fiber-reinforced composites against cobalt–chrome structures with ceramic veneering. Materials and methods: A total of 24 specimens (12 per group) simulating dental prosthetic frameworks were fabricated. The experimental specimens were subjected to a thermocycling aging process and to evaluate bond strength. All specimens were subjected to a three-point bending test to fracture using a universal testing machine Results: The cobalt–chrome/ceramic group yielded a bond strength value of 21.71 ± 2.16 MPa, while the carbon-fiber-reinforced composite group showed 14.50 ± 3.50 MPa. The failure assessment reported statistical significance between groups. Although carbon-fiber-reinforced composite group showed lower bond strength values, the chipping incidence in this group was as well lower. Conclusions: The chrome–cobalt/ceramic group showed greater bonding strength compared to the carbon-fiber-reinforced composite; most of the fractures within the cobalt–chrome/ceramic group, had no possibility of direct clinical repair., Depto. de Odontología Conservadora y Prótesis, Fac. de Odontología, TRUE, pub

The cured-in-place pipe (CIPP) method is currently the most frequently used approach for the renovation of piping without digging; this technology is suitable for pipes made from all types of material. The authors of this paper examined how chemical substances and increased temperature change samples of CIPP with vinyl-ester resin taken from a simulated installation. Changes were observed at several levels: visually via a digital optical microscope, through changes of short-term bending properties and by observation of the activity of the sample structure by means of acoustic emission (AE). Interdependencies among the observed parameters were examined, specifically, the cumulative number of hits (cnt)/deflection and flexural properties/mechanic wave velocity. The test results prove that after three weeks of immersion in a simulated aggressive environment that mirrors what may happen to CIPP in real conditions, short-term mechanical properties change. This is also proven by the results of the AE measurements. For clarity, the results include images from a digital optical microscope. In addition, this paper proves that CIPP samples have good resistance to the action of organic and inorganic acids and to increased temperatures. After three weeks of exposure to a temperature of 100 °C the CIPP flexural properties of the samples had even improved., Metoda cured in-place-pipe (CIPP) je nejčastěji používanou metodou bezvýkopové renovace potrubí v současnosti, přičemž tato technologie je vhodná pro všechny typy materiálu potrubí. Autoři článku se proto zaměřili na sledování změn na vzorcích potrubí CIPP s vinylesterovou pryskyřicí odebrané ze simulované instalace vlivem působení chemických látek nebo zvýšené teploty. Změny byly sledovány na několika úrovních: vizuálně, pomocí digitálního optického mikroskopu, změnou krátkodobých ohybových vlastností a současně sledováním změn aktivity struktury vzorku prostřednictvím akustické emise (AE). Sledována byla také závislost mezi posuzovanými parametry, a to kumulativní množství signálů (cnt / deformace a ohybové vlastnosti / mechanické rychlosti vln. Výsledky testů prokázaly, že po 3 týdnech uložení v simulovaném agresivním prostředí, které může působit na CIPP také v reálném provozu, dochází ke změně krátkodobých mechanických vlastností, což potvrdily i výsledky z měření akustické emise. Pro názornost jsou výsledky doplněny o snímky z digitálního optického mikroskopu. Byla prokázána dobrá odolnost vzorků CIPP vůči působení organických i anorganických kyselin a vůči zvýšeným teplotám, při třítýdenním působení teploty 100 °C na vzorky CIPP nastalo dokonce zlepšení ohybových vlastností.

Purpose: The aim of this comparative in vitro study was to assess the bond strength and mechanical failure of carbon-fiber-reinforced composites against cobalt–chrome structures with ceramic veneering. Materials and methods: A total of 24 specimens (12 per group) simulating dental prosthetic frameworks were fabricated. The experimental specimens were subjected to a thermocycling aging process and to evaluate bond strength. All specimens were subjected to a three-point bending test to fracture using a universal testing machine Results: The cobalt–chrome/ceramic group yielded a bond strength value of 21.71 ± 2.16 MPa, while the carbon-fiber-reinforced composite group showed 14.50 ± 3.50 MPa. The failure assessment reported statistical significance between groups. Although carbon-fiber-reinforced composite group showed lower bond strength values, the chipping incidence in this group was as well lower. Conclusions: The chrome–cobalt/ceramic group showed greater bonding strength compared to the carbon-fiber-reinforced composite; most of the fractures within the cobalt–chrome/ceramic group, had no possibility of direct clinical repair., Depto. de Odontología Conservadora y Prótesis, Fac. de Odontología, TRUE, pub

Purpose – The aim of this paper is to analyze the mechanical properties of acrylonitrile-butadiene-styrene (ABS) parts manufactured through fused filament fabrication and compare these results to analogous ones obtained on polylactic acid (PLA) and PLA–wood specimens to contribute for a wider understanding of the different materials used for additive manufacturing. Design/methodology/approach – With that aim, an experimental based on an L27 Taguchi array was used to combine the specific parameters taken into account in the study, namely, layer height, nozzle diameter, infill density, orientation and printing velocity. All samples were subjected to a four-point bending test performed according to the ASTM D6272 standard. Findings – Young’s modulus, elastic limit, maximum stress and maximum deformation of every sample were computed and subjected to an ANOVA. Results prove that layer height and nozzle diameter are the most significant factors that affect the mechanical resistance in pieces generated through additive manufacturing and subjected to bending loads, regardless of the material. Practical implications – The best results were obtained by combining a layer height of 0.1mm and a nozzle diameter of 0.6 mm. The comparison of materials evidenced that PLA and its composite version reinforced with wood particles present more rigidity than ABS, whereas the latter can experience further deflection before break. Originality/value – This study is of interest for manufacturers that want to decide which is the best material to be applied for their application, as it derives in a practical technical recommendation of the best parameters that should be selected to treat the material during the fused filament fabrication process., Postprint (author's final draft)

The cured-in-place pipe (CIPP) method is currently the most frequently used approach for the renovation of piping without digging; this technology is suitable for pipes made from all types of material. The authors of this paper examined how chemical substances and increased temperature change samples of CIPP with vinyl-ester resin taken from a simulated installation. Changes were observed at several levels: visually via a digital optical microscope, through changes of short-term bending properties and by observation of the activity of the sample structure by means of acoustic emission (AE). Interdependencies among the observed parameters were examined, specifically, the cumulative number of hits (cnt)/deflection and flexural properties/mechanic wave velocity. The test results prove that after three weeks of immersion in a simulated aggressive environment that mirrors what may happen to CIPP in real conditions, short-term mechanical properties change. This is also proven by the results of the AE measurements. For clarity, the results include images from a digital optical microscope. In addition, this paper proves that CIPP samples have good resistance to the action of organic and inorganic acids and to increased temperatures. After three weeks of exposure to a temperature of 100 °C the CIPP flexural properties of the samples had even improved., Metoda cured in-place-pipe (CIPP) je nejčastěji používanou metodou bezvýkopové renovace potrubí v současnosti, přičemž tato technologie je vhodná pro všechny typy materiálu potrubí. Autoři článku se proto zaměřili na sledování změn na vzorcích potrubí CIPP s vinylesterovou pryskyřicí odebrané ze simulované instalace vlivem působení chemických látek nebo zvýšené teploty. Změny byly sledovány na několika úrovních: vizuálně, pomocí digitálního optického mikroskopu, změnou krátkodobých ohybových vlastností a současně sledováním změn aktivity struktury vzorku prostřednictvím akustické emise (AE). Sledována byla také závislost mezi posuzovanými parametry, a to kumulativní množství signálů (cnt / deformace a ohybové vlastnosti / mechanické rychlosti vln. Výsledky testů prokázaly, že po 3 týdnech uložení v simulovaném agresivním prostředí, které může působit na CIPP také v reálném provozu, dochází ke změně krátkodobých mechanických vlastností, což potvrdily i výsledky z měření akustické emise. Pro názornost jsou výsledky doplněny o snímky z digitálního optického mikroskopu. Byla prokázána dobrá odolnost vzorků CIPP vůči působení organických i anorganických kyselin a vůči zvýšeným teplotám, při třítýdenním působení teploty 100 °C na vzorky CIPP nastalo dokonce zlepšení ohybových vlastností.

The cured-in-place pipe (CIPP) method is currently the most frequently used approach for the renovation of piping without digging; this technology is suitable for pipes made from all types of material. The authors of this paper examined how chemical substances and increased temperature change samples of CIPP with vinyl-ester resin taken from a simulated installation. Changes were observed at several levels: visually via a digital optical microscope, through changes of short-term bending properties and by observation of the activity of the sample structure by means of acoustic emission (AE). Interdependencies among the observed parameters were examined, specifically, the cumulative number of hits (cnt)/deflection and flexural properties/mechanic wave velocity. The test results prove that after three weeks of immersion in a simulated aggressive environment that mirrors what may happen to CIPP in real conditions, short-term mechanical properties change. This is also proven by the results of the AE measurements. For clarity, the results include images from a digital optical microscope. In addition, this paper proves that CIPP samples have good resistance to the action of organic and inorganic acids and to increased temperatures. After three weeks of exposure to a temperature of 100 °C the CIPP flexural properties of the samples had even improved., Metoda cured in-place-pipe (CIPP) je nejčastěji používanou metodou bezvýkopové renovace potrubí v současnosti, přičemž tato technologie je vhodná pro všechny typy materiálu potrubí. Autoři článku se proto zaměřili na sledování změn na vzorcích potrubí CIPP s vinylesterovou pryskyřicí odebrané ze simulované instalace vlivem působení chemických látek nebo zvýšené teploty. Změny byly sledovány na několika úrovních: vizuálně, pomocí digitálního optického mikroskopu, změnou krátkodobých ohybových vlastností a současně sledováním změn aktivity struktury vzorku prostřednictvím akustické emise (AE). Sledována byla také závislost mezi posuzovanými parametry, a to kumulativní množství signálů (cnt / deformace a ohybové vlastnosti / mechanické rychlosti vln. Výsledky testů prokázaly, že po 3 týdnech uložení v simulovaném agresivním prostředí, které může působit na CIPP také v reálném provozu, dochází ke změně krátkodobých mechanických vlastností, což potvrdily i výsledky z měření akustické emise. Pro názornost jsou výsledky doplněny o snímky z digitálního optického mikroskopu. Byla prokázána dobrá odolnost vzorků CIPP vůči působení organických i anorganických kyselin a vůči zvýšeným teplotám, při třítýdenním působení teploty 100 °C na vzorky CIPP nastalo dokonce zlepšení ohybových vlastností.

The cured-in-place pipe (CIPP) method is currently the most frequently used approach for the renovation of piping without digging; this technology is suitable for pipes made from all types of material. The authors of this paper examined how chemical substances and increased temperature change samples of CIPP with vinyl-ester resin taken from a simulated installation. Changes were observed at several levels: visually via a digital optical microscope, through changes of short-term bending properties and by observation of the activity of the sample structure by means of acoustic emission (AE). Interdependencies among the observed parameters were examined, specifically, the cumulative number of hits (cnt)/deflection and flexural properties/mechanic wave velocity. The test results prove that after three weeks of immersion in a simulated aggressive environment that mirrors what may happen to CIPP in real conditions, short-term mechanical properties change. This is also proven by the results of the AE measurements. For clarity, the results include images from a digital optical microscope. In addition, this paper proves that CIPP samples have good resistance to the action of organic and inorganic acids and to increased temperatures. After three weeks of exposure to a temperature of 100 °C the CIPP flexural properties of the samples had even improved., Metoda cured in-place-pipe (CIPP) je nejčastěji používanou metodou bezvýkopové renovace potrubí v současnosti, přičemž tato technologie je vhodná pro všechny typy materiálu potrubí. Autoři článku se proto zaměřili na sledování změn na vzorcích potrubí CIPP s vinylesterovou pryskyřicí odebrané ze simulované instalace vlivem působení chemických látek nebo zvýšené teploty. Změny byly sledovány na několika úrovních: vizuálně, pomocí digitálního optického mikroskopu, změnou krátkodobých ohybových vlastností a současně sledováním změn aktivity struktury vzorku prostřednictvím akustické emise (AE). Sledována byla také závislost mezi posuzovanými parametry, a to kumulativní množství signálů (cnt / deformace a ohybové vlastnosti / mechanické rychlosti vln. Výsledky testů prokázaly, že po 3 týdnech uložení v simulovaném agresivním prostředí, které může působit na CIPP také v reálném provozu, dochází ke změně krátkodobých mechanických vlastností, což potvrdily i výsledky z měření akustické emise. Pro názornost jsou výsledky doplněny o snímky z digitálního optického mikroskopu. Byla prokázána dobrá odolnost vzorků CIPP vůči působení organických i anorganických kyselin a vůči zvýšeným teplotám, při třítýdenním působení teploty 100 °C na vzorky CIPP nastalo dokonce zlepšení ohybových vlastností.

The cured-in-place pipe (CIPP) method is currently the most frequently used approach for the renovation of piping without digging; this technology is suitable for pipes made from all types of material. The authors of this paper examined how chemical substances and increased temperature change samples of CIPP with vinyl-ester resin taken from a simulated installation. Changes were observed at several levels: visually via a digital optical microscope, through changes of short-term bending properties and by observation of the activity of the sample structure by means of acoustic emission (AE). Interdependencies among the observed parameters were examined, specifically, the cumulative number of hits (cnt)/deflection and flexural properties/mechanic wave velocity. The test results prove that after three weeks of immersion in a simulated aggressive environment that mirrors what may happen to CIPP in real conditions, short-term mechanical properties change. This is also proven by the results of the AE measurements. For clarity, the results include images from a digital optical microscope. In addition, this paper proves that CIPP samples have good resistance to the action of organic and inorganic acids and to increased temperatures. After three weeks of exposure to a temperature of 100 °C the CIPP flexural properties of the samples had even improved., Metoda cured in-place-pipe (CIPP) je nejčastěji používanou metodou bezvýkopové renovace potrubí v současnosti, přičemž tato technologie je vhodná pro všechny typy materiálu potrubí. Autoři článku se proto zaměřili na sledování změn na vzorcích potrubí CIPP s vinylesterovou pryskyřicí odebrané ze simulované instalace vlivem působení chemických látek nebo zvýšené teploty. Změny byly sledovány na několika úrovních: vizuálně, pomocí digitálního optického mikroskopu, změnou krátkodobých ohybových vlastností a současně sledováním změn aktivity struktury vzorku prostřednictvím akustické emise (AE). Sledována byla také závislost mezi posuzovanými parametry, a to kumulativní množství signálů (cnt / deformace a ohybové vlastnosti / mechanické rychlosti vln. Výsledky testů prokázaly, že po 3 týdnech uložení v simulovaném agresivním prostředí, které může působit na CIPP také v reálném provozu, dochází ke změně krátkodobých mechanických vlastností, což potvrdily i výsledky z měření akustické emise. Pro názornost jsou výsledky doplněny o snímky z digitálního optického mikroskopu. Byla prokázána dobrá odolnost vzorků CIPP vůči působení organických i anorganických kyselin a vůči zvýšeným teplotám, při třítýdenním působení teploty 100 °C na vzorky CIPP nastalo dokonce zlepšení ohybových vlastností.

The cured-in-place pipe (CIPP) method is currently the most frequently used approach for the renovation of piping without digging; this technology is suitable for pipes made from all types of material. The authors of this paper examined how chemical substances and increased temperature change samples of CIPP with vinyl-ester resin taken from a simulated installation. Changes were observed at several levels: visually via a digital optical microscope, through changes of short-term bending properties and by observation of the activity of the sample structure by means of acoustic emission (AE). Interdependencies among the observed parameters were examined, specifically, the cumulative number of hits (cnt)/deflection and flexural properties/mechanic wave velocity. The test results prove that after three weeks of immersion in a simulated aggressive environment that mirrors what may happen to CIPP in real conditions, short-term mechanical properties change. This is also proven by the results of the AE measurements. For clarity, the results include images from a digital optical microscope. In addition, this paper proves that CIPP samples have good resistance to the action of organic and inorganic acids and to increased temperatures. After three weeks of exposure to a temperature of 100 °C the CIPP flexural properties of the samples had even improved., Metoda cured in-place-pipe (CIPP) je nejčastěji používanou metodou bezvýkopové renovace potrubí v současnosti, přičemž tato technologie je vhodná pro všechny typy materiálu potrubí. Autoři článku se proto zaměřili na sledování změn na vzorcích potrubí CIPP s vinylesterovou pryskyřicí odebrané ze simulované instalace vlivem působení chemických látek nebo zvýšené teploty. Změny byly sledovány na několika úrovních: vizuálně, pomocí digitálního optického mikroskopu, změnou krátkodobých ohybových vlastností a současně sledováním změn aktivity struktury vzorku prostřednictvím akustické emise (AE). Sledována byla také závislost mezi posuzovanými parametry, a to kumulativní množství signálů (cnt / deformace a ohybové vlastnosti / mechanické rychlosti vln. Výsledky testů prokázaly, že po 3 týdnech uložení v simulovaném agresivním prostředí, které může působit na CIPP také v reálném provozu, dochází ke změně krátkodobých mechanických vlastností, což potvrdily i výsledky z měření akustické emise. Pro názornost jsou výsledky doplněny o snímky z digitálního optického mikroskopu. Byla prokázána dobrá odolnost vzorků CIPP vůči působení organických i anorganických kyselin a vůči zvýšeným teplotám, při třítýdenním působení teploty 100 °C na vzorky CIPP nastalo dokonce zlepšení ohybových vlastností.

学位の種類: 博士（歯学）. 報告番号: 甲第4590号. 学位記番号: 新大院博（歯）甲第439号. 学位授与年月日: 平成31年3月25日, Dentistry. 2018, 8(11), 524, 博士（歯学）, 新潟大学

This paper aims to analyse the mechanical properties response of polylactic acid (PLA) parts manufactured through fused filament fabrication. The influence of six manufacturing factors (layer height, filament width, fill density, layer orientation, printing velocity, and infill pattern) on the flexural resistance of PLA specimens is studied through an L27 Taguchi experimental array. Different geometries were tested on a four-point bending machine and on a rotating bending machine. From the first experimental phase, an optimal set of parameters deriving in the highest flexural resistance was determined. The results show that layer orientation is the most influential parameter, followed by layer height, filament width, and printing velocity, whereas the fill density and infill pattern show no significant influence. Finally, the fatigue fracture behaviour is evaluated and compared with that of previous studies’ results, in order to present a comprehensive study of the mechanical properties of the material under different kind of solicitations., Peer Reviewed, Postprint (published version)

A study on the hybrid composites reinforced by two types of short natural fibres is presented. The material properties of short natural fibre composites were obtained by Mori–Tanaka method. Three-point bend test was simulated by the classical beam theory and finite element analysis. Both asymmetric and sandwich hybrid composites were studied. From the results, the following conclusions can be drawn: 1. A general rule is that one lamina of higher stiffness should be placed on the tensile face of a hybrid composite in order to obtain improved flexural strength. 2. For the sandwich-type hybrid composites, the higher stiffness material should be placed in the core, and the lower stiffness material should be the skin.

This research paper deals with an influence of reinforcing polymer ribs on selected mechanical properties of sandwich structures. Reinforcing epoxy ribs are produced directly by the vacuum infusion technology when resin during its flow fills the prepared holes in the polymer core. In the experiment, two rib sizes (diameters) were tested as well as two variants of hole patterns on the core surface. The possible influence of the core material was evaluated on two core material types with different thicknesses. In addition to the observed mechanical properties observed, the types of failure and changes of the sandwich panels weight were also characterized. The obtained results show a significant increase in flexural strength and stiffness of all types and shapes of prepared reinforcing polymer ribs. Positive effect was also observed in the case of edgewise compression load capacity. © 2018. Published by Manufacturing Technology.

Fused deposition modelling (FDM) is one of the leading additive manufacturing technologies for producing plastic parts in a layer by layer manner d from a digital file. The actual levels of processed parameters of the manufactured parts using fused deposition modelling (FDM) are considered the major obstruction to optimize the mechanical properties. As a result of the FDM parameters and the interaction among them the parts' mechanical properties of the manufactured parts are affected, thus, many experiments have been dedicated to find the proper parameter setting. This paper presents a study on the influence of three FDM process parameters (air gap, raster angle, and build orientation) on the flexural strength of the FDM Nylon 12 manufactured parts. Response surface methodology (RSM) is used as a statistical technique to analyse results. Analysis of variance (ANOVA) method is also used to test the significance of parameters. The results indicate that the air gap and raster angle are the most influential parameters affecting the flexural strength.

This study compared the performance of strandboards made from trembling aspen, a lowdensity hardwood species, with strandboards made from paper birch, a medium-density hardwood species. Strands were cut into three different lengths (78, 105, and 142 mm) and two thicknesses (0.55 and 0.75 mm) to compare the impact of species, strand geometry, specific surface, and slenderness ratio. Internal bond (IB), modulus of elasticity (MOE), and modulus of rupture (MOR) for flatwise and edgewise bending, compressive strength, and stiffness were all determined. Both species performed equally well in IB (0.73 MPa for both species combined). The highest MOE and MOR values in flatwise and edgewise bending were obtained for long, thin strands and were significantly lower for birch than for aspen panels (flatwise: 13.6 GPa and 99.2 MPa for aspen and 12.1 GPa and 85.5 MPa for birch; edgewise: 13.5 GPa and 66.3 MPa for aspen and 13.2 GPa and 65.7 MPa for birch). Short aspen strands resulted in the highest compressive properties, slightly higher than those of short birch strands (aspen: compressive strength 10.4 MPa and stiffness 1.22 GPa; birch: 10.8 MPa and 2.25 GPa, respectively). Strand length must therefore be a compromise between the need for high bending properties provided by long strands and the need for high compressive properties provided by short strands.

The replacement of commodity polyolefin, reinforced with glass fiber (GF), by greener alternatives has been a topic of research in recent years. Cellulose fibers have shown, under certain conditions, enough tensile capacities to replace GF, achieving competitive mechanical properties. However, if the objective is the production of environmentally friendlier composites, it is necessary to replace oil-derived polymer matrices by bio-based or biodegradable ones, depending on the application. Polyamide 11 (PA11) is a totally bio-based polyamide that can be reinforced with cellulosic fibers. Composites based on this polymer have demonstrated enough tensile strength, as well as stiffness, to replace GF-reinforced polypropylene (PP). However, flexural properties are of high interest for engineering applications. Due to the specific character of short-fiber-reinforced composites, significant differences are expected between the tensile and flexural properties. These differences encourage the study of the flexural properties of a material prior to the design or development of a new product. Despite the importance of the flexural strength, there are few works devoted to its study in the case of PA11-based composites. In this work, an in-depth study of the flexural strength of PA11 composites, reinforced with Stoneground wood (SGW) from softwood, is presented. Additionally, the results are compared with those of PP-based composites. The results showed that the SGW fibers had lower strengthening capacity reinforcing PA11 than PP. Moreover, the flexural strength of PA11-SGW composites was similar to that of PP-GF composites, Postprint (published version)

This research paper deals with an influence of reinforcing polymer ribs on selected mechanical properties of sandwich structures. Reinforcing epoxy ribs are produced directly by the vacuum infusion technology when resin during its flow fills the prepared holes in the polymer core. In the experiment, two rib sizes (diameters) were tested as well as two variants of hole patterns on the core surface. The possible influence of the core material was evaluated on two core material types with different thicknesses. In addition to the observed mechanical properties observed, the types of failure and changes of the sandwich panels weight were also characterized. The obtained results show a significant increase in flexural strength and stiffness of all types and shapes of prepared reinforcing polymer ribs. Positive effect was also observed in the case of edgewise compression load capacity. © 2018. Published by Manufacturing Technology.

The purpose of the work is the determination of flexural properties for thebiocomposite Durapulp. The study includes laborative tests on Durapulp andreference materials, commonly used in the building sector. Stiffness and strength of Durapulp show that it has the potential as a replacement for conventional wood-based materials.

Evaluación y análisis de cuatro antidegradantes no manchantes derivados de ceras parafínicas y fenoles, en las propiedades mecánicas del caucho de la suela del calzado fabricada por Croydon Colombia S.A. S e desarrolla una pre-experimentación con el fin de conocer el comportamiento de cada antidegradante a diferentes dosificaciones con respecto a las propiedades de abrasión y flexión, identificando aquellos con valores más altos en la última de las pruebas mecánicas.

The purpose of the work is the determination of flexural properties for thebiocomposite Durapulp. The study includes laborative tests on Durapulp andreference materials, commonly used in the building sector. Stiffness and strength of Durapulp show that it has the potential as a replacement for conventional wood-based materials.

Evaluación y análisis de cuatro antidegradantes no manchantes derivados de ceras parafínicas y fenoles, en las propiedades mecánicas del caucho de la suela del calzado fabricada por Croydon Colombia S.A. S e desarrolla una pre-experimentación con el fin de conocer el comportamiento de cada antidegradante a diferentes dosificaciones con respecto a las propiedades de abrasión y flexión, identificando aquellos con valores más altos en la última de las pruebas mecánicas.

Jute fabric is well-known reinforcing material in composite science, however, there is a necessity to treat these fabrics to reduce moisture uptake and improve properties. Nevertheless, every modification increases the cost and reduces the possible applications. Presented research deals with an investigation of possibility to use untreated jute in various fabric weight as a reinforcing material in sandwich structures facings. Untreated jute reinforcements andtwo types of cork coreswere saturated in one step during vacuum infusion creating a lightweight sandwich composite. All samples were mechanically tested in three-point bending test. Experimental results showed the most appropriate material combination and produced sandwich structure are proposed for design applications. © 2017 Trans Tech Publications, Switzerland.

Evaluación y análisis de cuatro antidegradantes no manchantes derivados de ceras parafínicas y fenoles, en las propiedades mecánicas del caucho de la suela del calzado fabricada por Croydon Colombia S.A. S e desarrolla una pre-experimentación con el fin de conocer el comportamiento de cada antidegradante a diferentes dosificaciones con respecto a las propiedades de abrasión y flexión, identificando aquellos con valores más altos en la última de las pruebas mecánicas.

Evaluación y análisis de cuatro antidegradantes no manchantes derivados de ceras parafínicas y fenoles, en las propiedades mecánicas del caucho de la suela del calzado fabricada por Croydon Colombia S.A. S e desarrolla una pre-experimentación con el fin de conocer el comportamiento de cada antidegradante a diferentes dosificaciones con respecto a las propiedades de abrasión y flexión, identificando aquellos con valores más altos en la última de las pruebas mecánicas.

A detailed investigation of physical, mechanical and thermal properties of jute and bamboo fiber reinforced epoxy resin unidirectional void free composites was carried out. The composites were prepared by using vacuum technique. Scanning electron microscopic analysis, tensile and flexural testing and thermogravimetric analysis were performed in order to evaluate surface morphology, mechanical properties and thermal behavior of the unidirectional composites respectively. The relationship between theoretical and experimental values was figured out using rules of mixture. The analytical results showed good agreement with the experimental results. Comparing jute and bamboo fiber reinforced unidirectional composites, it is observed that bamboo fiber reinforced epoxy composites showed good results in terms of tensile strength, while jute fiber reinforced epoxy composites had higher Young's modulus values. Bamboo fiber reinforced epoxy composites showed good flexure strength in the longitudinal distribution. On the other hand, jute fiber reinforced epoxy composited had better flexural strength with transverse fiber distribution in the composites. Fiber distribution was not uniform for both bamboo and jute fiber reinforced unidirectional epoxy composites. Scanning electron microscopic analysis showed that morphological changes took place depending on the fiber orientation in epoxy composites. It is also observed from thermogravimetric analysis that jute fiber reinforced epoxy composites had better thermal behavior compared to bamboo fiber reinforced epoxy composites.

This paper presents an experimental investigation of mechanical and impact properties of carbon and Kevlar-carbon composites prepared from pre-impregnated materials. Namely, flexural performance in three-point bending at different temperatures is evaluated. Moreover, low-velocity impact test is also conducted for classification of impact properties and character of rupture. These all properties are important for material design of sport bike rims.

The paper provides experimental results of tensile and flexural tests of HPL composites. Mechanical properties of HPL laminates from four worldwide producers (Fundermax, Polyrey, Abet and Rexin) are compared. Composites are compared due to their stiffness and strength, both tensile and flexural. The exterior environment effect on mechanical behaviour of composites in service load conditions is presented, too.

The paper provides experimental results of tensile and flexural tests of HPL composites. Mechanical properties of HPL laminates from four worldwide producers (Fundermax, Polyrey, Abet and Rexin) are compared. Composites are compared due to their stiffness and strength, both tensile and flexural. The exterior environment effect on mechanical behaviour of composites in service load conditions is presented, too.

The popularity and demand for wood plastic composites (WPC) has focused research on fiber properties associated with performance. In this study, maple wood fibers (WF) were ball milled and classified into discrete size fractions. Fiber analyses showed only three distinct WF size classes (80-100, 100-200 and <200 mesh). High density polyethylene (HDPE) based WPC were made from classified WF (10 to 50%). The effect of WF size, loading, and maleated polyethylene (MAPE) coupling agent on WPC rheological behavior (torque rheometry and melt flow rate (MFR)) and flexural properties were examined. The WPC MFR decreased with wood loading, increased with a reduction in WF size. The modulus of rupture (MOR) was shown to increase with a reduction in WF size and increase with the addition of MAPE. The increase in MOR is likely due to an increase in the interfacial interaction between the polymer and WF. Modulus of elasticity (MOE) was shown to increase with an increase in wood loading and decrease with a decrease in WF size. The toughness of the WPC was shown to increase with a decrease in WF size and increase upon addition of MAPE.