Particulate reinforced composites include functionally graded materials that are to be exposed to extremely high temperatures at one side and extremely low temperature at another side. In this paper, the steady-state temperature field in particulate reinforced composites is derived using the Green’s function expressed by a linear combination of the eigenfunctions for the given geometry and the boundary conditions. The trial functions that are used to construct the Green’s functions are those that warrant continuous temperature and heat flux across the material boundary (heat-flux-conserving trial functions). The solution by the proposed method is compared to the finite element solution for accuracy.
{"title":"Micromechanical Study of Particulate Reinforced Composites","authors":"D. Choi, S. Nomura","doi":"10.1115/imece1996-0466","DOIUrl":"https://doi.org/10.1115/imece1996-0466","url":null,"abstract":"\u0000 Particulate reinforced composites include functionally graded materials that are to be exposed to extremely high temperatures at one side and extremely low temperature at another side. In this paper, the steady-state temperature field in particulate reinforced composites is derived using the Green’s function expressed by a linear combination of the eigenfunctions for the given geometry and the boundary conditions. The trial functions that are used to construct the Green’s functions are those that warrant continuous temperature and heat flux across the material boundary (heat-flux-conserving trial functions). The solution by the proposed method is compared to the finite element solution for accuracy.","PeriodicalId":326220,"journal":{"name":"Aerospace and Materials","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125999997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Modeling of porosity effects on the thermal-chemical decomposition of porous, polymer composites at high temperature is treated analytically for no gas flow and compared with finite element results which permit gas flow. A function is proposed for the variation of Biot’s pressure-stress coupling factor in terms of porosity and a constant which can be determined from experiments. The results show this function adequately describes the coupling factor and that the inclusion of gas flow (permeability) is essential to accurate results.
{"title":"Modeling of Porosity Effects in Gas-Filled Composites Using Biot’s Parameter","authors":"N. Salamon, R. Ganesan","doi":"10.1115/imece1996-0467","DOIUrl":"https://doi.org/10.1115/imece1996-0467","url":null,"abstract":"\u0000 Modeling of porosity effects on the thermal-chemical decomposition of porous, polymer composites at high temperature is treated analytically for no gas flow and compared with finite element results which permit gas flow. A function is proposed for the variation of Biot’s pressure-stress coupling factor in terms of porosity and a constant which can be determined from experiments. The results show this function adequately describes the coupling factor and that the inclusion of gas flow (permeability) is essential to accurate results.","PeriodicalId":326220,"journal":{"name":"Aerospace and Materials","volume":"269 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114475944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A pultruded rod reinforced composite which can eliminate presence of fiber waviness and reduce cost of laminate manufacturing has become a focus interest to aircraft manufacturers. Due to its characteristics of rod layer, conventional analysis which use the smeared properties across the entire rod layer fails to predict the structural response of this rod reinforced laminates. A closed-form expression was derived and a finite element analysis was conducted for predicting the critical buckling load for this type of laminates with a damage. Damage considered include broken rods, rods split vertically and horizontally, and delamination between the rod layer and angle plies. It is concluded that damages with rods split horizontally and a delamination can reduce the buckling load. For the rods broken, the buckling load will be reduced if a broken space is included. However, the buckling load remains unchanged if rods split vertically.
{"title":"Effects of Defects in a New Form of Affordable Composite Materials-Rod Reinforcement","authors":"W. Chan, J. S. Wang","doi":"10.1115/imece1996-0489","DOIUrl":"https://doi.org/10.1115/imece1996-0489","url":null,"abstract":"\u0000 A pultruded rod reinforced composite which can eliminate presence of fiber waviness and reduce cost of laminate manufacturing has become a focus interest to aircraft manufacturers. Due to its characteristics of rod layer, conventional analysis which use the smeared properties across the entire rod layer fails to predict the structural response of this rod reinforced laminates. A closed-form expression was derived and a finite element analysis was conducted for predicting the critical buckling load for this type of laminates with a damage. Damage considered include broken rods, rods split vertically and horizontally, and delamination between the rod layer and angle plies. It is concluded that damages with rods split horizontally and a delamination can reduce the buckling load. For the rods broken, the buckling load will be reduced if a broken space is included. However, the buckling load remains unchanged if rods split vertically.","PeriodicalId":326220,"journal":{"name":"Aerospace and Materials","volume":"197 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121145205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The micromechanisms of fatigue failure of a short, alumina-silicate fiber reinforced cast aluminum alloy (A356) are investigated in this study. The nature of damage evolution is studied by three complementary perspectives — i) monitoring of the mechanical response, ii) microscopy on the gage length and fracture surface, and iii) probing of the microstructural changes in the bulk nondestructively using acoustic emission. The damage evolution in the composite is driven by strain or fatigue cycles imposed on the specimen and is manifested as three distinct mechanisms: a) cracking at hollow shot particles early in the life, b) microcracking in the form of fracture of fibers oriented in the direction of the loading and splitting or decohesion at fiber/matrix interface of transversely oriented fibers, and c) void formation at fiber ends and other stress concentrations. The interaction among the different modes, which defines the evolution of microstructural damage, is described. A flow chart for the progression of damage is presented and the most important steps in the damage evolution are identified. Suggestions are made for improving fatigue performance by tailoring the microstructure of the composite.
{"title":"Fatigue Damage Evolution in a Short Fiber Reinforced Metal Matrix Composite","authors":"S. Canumalla, Robert N. Pangborn","doi":"10.1115/imece1996-0498","DOIUrl":"https://doi.org/10.1115/imece1996-0498","url":null,"abstract":"\u0000 The micromechanisms of fatigue failure of a short, alumina-silicate fiber reinforced cast aluminum alloy (A356) are investigated in this study. The nature of damage evolution is studied by three complementary perspectives — i) monitoring of the mechanical response, ii) microscopy on the gage length and fracture surface, and iii) probing of the microstructural changes in the bulk nondestructively using acoustic emission. The damage evolution in the composite is driven by strain or fatigue cycles imposed on the specimen and is manifested as three distinct mechanisms: a) cracking at hollow shot particles early in the life, b) microcracking in the form of fracture of fibers oriented in the direction of the loading and splitting or decohesion at fiber/matrix interface of transversely oriented fibers, and c) void formation at fiber ends and other stress concentrations. The interaction among the different modes, which defines the evolution of microstructural damage, is described. A flow chart for the progression of damage is presented and the most important steps in the damage evolution are identified. Suggestions are made for improving fatigue performance by tailoring the microstructure of the composite.","PeriodicalId":326220,"journal":{"name":"Aerospace and Materials","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114385535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To increase energy efficiency, new plants must operate at higher and higher temperatures. Moreover, power generation equipment continues to age and is being used far beyond its intended original design life. Some recent failures which unfortunately occurred with serious consequences have clearly illustrated that current methods for insuring safety and reliability of high temperature equipment is inadequate. Because of these concerns, an understanding of the high-temperature crack growth process is very important and has led to the following studies of the high temperature failure process. This effort summarizes the results of some recent studies which investigate the phenomenon of high temperature creep fatigue crack growth. Experimental results which detail the process of creep fatigue, analytical studies which investigate why current methods are ineffective, and finally, a new approach which is based on the T*integral and its ability to characterize the creep-fatigue crack growth process are discussed. The potential validity of this new predictive methodology is illustrated.
{"title":"Deformation and Fracture Response of Steel at High Temperature","authors":"F. Brust, Jinmiao Zhang","doi":"10.1115/imece1996-0465","DOIUrl":"https://doi.org/10.1115/imece1996-0465","url":null,"abstract":"\u0000 To increase energy efficiency, new plants must operate at higher and higher temperatures. Moreover, power generation equipment continues to age and is being used far beyond its intended original design life. Some recent failures which unfortunately occurred with serious consequences have clearly illustrated that current methods for insuring safety and reliability of high temperature equipment is inadequate. Because of these concerns, an understanding of the high-temperature crack growth process is very important and has led to the following studies of the high temperature failure process.\u0000 This effort summarizes the results of some recent studies which investigate the phenomenon of high temperature creep fatigue crack growth. Experimental results which detail the process of creep fatigue, analytical studies which investigate why current methods are ineffective, and finally, a new approach which is based on the T*integral and its ability to characterize the creep-fatigue crack growth process are discussed. The potential validity of this new predictive methodology is illustrated.","PeriodicalId":326220,"journal":{"name":"Aerospace and Materials","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124902930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A micromechanics study is made of the rate-dependent thermal softening behavior of a tungsten matrix composite containing glassy particles. Under adiabatic compression of the composite, the elastic glassy particles thermally soften at relatively high strains, enhancing the thermal softening of the tungsten-based composite, thus reducing the strain rate sensitivity and fostering shear localization. To guide the microstructural design of the particle-modified tungsten-based composite in penetration applications, systematic predictions are made for the stress-strain behavior of the composite under overall adiabatic compression with different temperature-dependent behaviors, sizes, volume fractions of the particle and applied strain rates. It is found that both the onset and the rate of thermal softening of the composite depend critically on the applied strain rate. Owing to thermal softening of the glassy particles, the strain-rate sensitivity of the composite is reduced.
{"title":"Thermal Softening of Glassy Particle Modified Tungsten","authors":"P. Leduc, G. Bao","doi":"10.1115/imece1996-0500","DOIUrl":"https://doi.org/10.1115/imece1996-0500","url":null,"abstract":"\u0000 A micromechanics study is made of the rate-dependent thermal softening behavior of a tungsten matrix composite containing glassy particles. Under adiabatic compression of the composite, the elastic glassy particles thermally soften at relatively high strains, enhancing the thermal softening of the tungsten-based composite, thus reducing the strain rate sensitivity and fostering shear localization. To guide the microstructural design of the particle-modified tungsten-based composite in penetration applications, systematic predictions are made for the stress-strain behavior of the composite under overall adiabatic compression with different temperature-dependent behaviors, sizes, volume fractions of the particle and applied strain rates. It is found that both the onset and the rate of thermal softening of the composite depend critically on the applied strain rate. Owing to thermal softening of the glassy particles, the strain-rate sensitivity of the composite is reduced.","PeriodicalId":326220,"journal":{"name":"Aerospace and Materials","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117219363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Three types of material variations commonly introduced during the processing of polymeric matrix composite materials are considered. These are (i) deviations from the local fiber volume fraction from the design specifications, (ii) non-uniformity in the inter-fiber spacing, and (iii) the presence of substantial levels of local void distribution. The influence of these variabilities on the longitudinal tensile strength of unidirectional composite material is evaluated. For composite materials with uniform fiber distribution, the tensile strength slightly dropped as the fiber volume fraction was increased. The non-uniformity in the inter-fiber spacing and the presence of significant levels of voids was found to have a more adverse influence on the tensile strength.
{"title":"The Influence of Fiber Distribution and Voids on the Tensile Strength of Polymer Composite Materials","authors":"G. Generalis, M. Sundaresan","doi":"10.1115/imece1996-0501","DOIUrl":"https://doi.org/10.1115/imece1996-0501","url":null,"abstract":"\u0000 Three types of material variations commonly introduced during the processing of polymeric matrix composite materials are considered. These are (i) deviations from the local fiber volume fraction from the design specifications, (ii) non-uniformity in the inter-fiber spacing, and (iii) the presence of substantial levels of local void distribution. The influence of these variabilities on the longitudinal tensile strength of unidirectional composite material is evaluated. For composite materials with uniform fiber distribution, the tensile strength slightly dropped as the fiber volume fraction was increased. The non-uniformity in the inter-fiber spacing and the presence of significant levels of voids was found to have a more adverse influence on the tensile strength.","PeriodicalId":326220,"journal":{"name":"Aerospace and Materials","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127115218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One of the most severe problems associated with the use of laminated composite structures in thermal environments is the susceptibility to delamination due to the edge effect stresses arising from the thermal expansion mismatch between the constituent laminae. In addition, the problem may be compounded by the introduction of extreme thermal gradient effects as well. Trade studies to develop a satisfactory design for these types of thermal environments have heretofore been rather limited due to the lack of accurate analytical assessments for the edge effects that arise from these thermal loads. The predominant amount of investigation for these types of thermal gradient problems has been restricted to detailed numerical finite element analyses that do not lend to rapid concurrent engineering design processes. No analytical solution has been available to address the thermoelastic edge effects in composite laminates resulting from thermal gradients. In this paper, a combination of Airy stress functions and direct displacement functions is utilized to obtain the plane elasticity solution for the stresses and displacements in a multilayer laminated anisotropic strip subjected to a temperature gradient that is arbitrarily symmetric in the longitudinal direction. The solution cannot be guaranteed to satisfy the free edge normal traction requirement since only resultant force is enforced to zero; however, convergence for enforced zero transverse slope at the strip ends can be established, as the eigenfunctions are orthogonal. Thus the solution is exact for these edge conditions. Numerical results are presented for several examples and compared to those obtained from our own MSC/NASTRAN finite element analyses. The correlation with the finite element numerical results was determined to verify the solution and indicated application of the solution as an approximation to free edge engineering problems is very reasonable for a broad range of practical cases involving temperature gradient effects.
{"title":"Edge Stresses in a Laminated Composite Strip Subjected to Axial Temperature Gradients","authors":"D. Swett, G. Shiflett","doi":"10.1115/imece1996-0477","DOIUrl":"https://doi.org/10.1115/imece1996-0477","url":null,"abstract":"\u0000 One of the most severe problems associated with the use of laminated composite structures in thermal environments is the susceptibility to delamination due to the edge effect stresses arising from the thermal expansion mismatch between the constituent laminae. In addition, the problem may be compounded by the introduction of extreme thermal gradient effects as well. Trade studies to develop a satisfactory design for these types of thermal environments have heretofore been rather limited due to the lack of accurate analytical assessments for the edge effects that arise from these thermal loads. The predominant amount of investigation for these types of thermal gradient problems has been restricted to detailed numerical finite element analyses that do not lend to rapid concurrent engineering design processes. No analytical solution has been available to address the thermoelastic edge effects in composite laminates resulting from thermal gradients.\u0000 In this paper, a combination of Airy stress functions and direct displacement functions is utilized to obtain the plane elasticity solution for the stresses and displacements in a multilayer laminated anisotropic strip subjected to a temperature gradient that is arbitrarily symmetric in the longitudinal direction. The solution cannot be guaranteed to satisfy the free edge normal traction requirement since only resultant force is enforced to zero; however, convergence for enforced zero transverse slope at the strip ends can be established, as the eigenfunctions are orthogonal. Thus the solution is exact for these edge conditions. Numerical results are presented for several examples and compared to those obtained from our own MSC/NASTRAN finite element analyses. The correlation with the finite element numerical results was determined to verify the solution and indicated application of the solution as an approximation to free edge engineering problems is very reasonable for a broad range of practical cases involving temperature gradient effects.","PeriodicalId":326220,"journal":{"name":"Aerospace and Materials","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121541473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Understanding the behavior of the fiber/matrix interface region over a range of temperatures is essential for designing composites that will have a high service temperature. In the current work, the interface failure sequence was observed during fiber pushout tests on two model composites (steel/epoxy and polyester/epoxy) with different Young’s moduli ratio and residual stress values. Novel photoelastic experiments were conducted on the model composites to measure the interfacial crack length versus load during the fiber push-out test. The data were used to better understand the failure mechanisms during the test and to determine the range of applicability of analytical and computational models of the test. Debonding was observed to occur from either the top or the bottom of the sample depending on the ratio of the elastic moduli of the fiber and matrix and the residual stress state. The pushout data from a polyester/epoxy system which debonded from the top was fit to a shear lag solution to obtain the fiber-matrix interfacial toughness (GIIc). The resulting interfacial toughness was then used to check the predicted debond length as a function of pushout force. The debond length calculated from the shear lag model was less than the measured debond length by a nearly constant 1.5 fiber radii which may correspond to the thickness of the surface effects region for polyester/epoxy. In the future, the results of the model experiments will be used to understand the interfacial properties of two representative high temperature composites, SiC/Ti-Al-V and Al2O3/Ti-Al-V. A special high temperature apparatus was constructed for performing the push-out test at temperatures ranging from room temperature to 1000°C under vacuum. Performing interfacial measurements at elevated temperatures can be used to optimize interfacial performance at service temperatures and to better evaluate the effects of residual stresses and matrix ductility on fiber debonding and sliding.
{"title":"Determination of Interfacial Fracture Toughness in High Temperature Composites","authors":"V. T. Bechel, N. Sottos","doi":"10.1115/imece1996-0475","DOIUrl":"https://doi.org/10.1115/imece1996-0475","url":null,"abstract":"\u0000 Understanding the behavior of the fiber/matrix interface region over a range of temperatures is essential for designing composites that will have a high service temperature. In the current work, the interface failure sequence was observed during fiber pushout tests on two model composites (steel/epoxy and polyester/epoxy) with different Young’s moduli ratio and residual stress values. Novel photoelastic experiments were conducted on the model composites to measure the interfacial crack length versus load during the fiber push-out test. The data were used to better understand the failure mechanisms during the test and to determine the range of applicability of analytical and computational models of the test. Debonding was observed to occur from either the top or the bottom of the sample depending on the ratio of the elastic moduli of the fiber and matrix and the residual stress state. The pushout data from a polyester/epoxy system which debonded from the top was fit to a shear lag solution to obtain the fiber-matrix interfacial toughness (GIIc). The resulting interfacial toughness was then used to check the predicted debond length as a function of pushout force. The debond length calculated from the shear lag model was less than the measured debond length by a nearly constant 1.5 fiber radii which may correspond to the thickness of the surface effects region for polyester/epoxy.\u0000 In the future, the results of the model experiments will be used to understand the interfacial properties of two representative high temperature composites, SiC/Ti-Al-V and Al2O3/Ti-Al-V. A special high temperature apparatus was constructed for performing the push-out test at temperatures ranging from room temperature to 1000°C under vacuum. Performing interfacial measurements at elevated temperatures can be used to optimize interfacial performance at service temperatures and to better evaluate the effects of residual stresses and matrix ductility on fiber debonding and sliding.","PeriodicalId":326220,"journal":{"name":"Aerospace and Materials","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114254146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An overview of the response of 2-D woven and 3-D braided SiC/SiC composites to thermomechanical loading up to a temperature of 1300°C is presented. The composites utilize Nicalon SiC fibers and are manufactured by the chemical vapor infiltration process. Fiber architecture controls the damage behavior of the composites both directly and indirectly by determining the sizes and distributions of microstructural pores within and between fiber bundles. The role of porosity on damage evolution is investigated by studying SiC/SiC composites with two porosity levels. A damage mechanics model based on Ladeveze’s approach is used to analyze the damage behavior of the composites. In addition to failure under tension, compression and bending, the fracture behavior of 2-D SiC/SiC composites is characterized through the application of various energy approaches based on the linear elastic fracture mechanics and J-integral methods. The toughness parameters thus obtained are compared and the suitability of the approaches discussed.
{"title":"Durability and Damage Bahavior of 2-D and 3-D SiC/SiC Composites","authors":"A. Parvizi-Majidi,","doi":"10.1115/imece1996-0493","DOIUrl":"https://doi.org/10.1115/imece1996-0493","url":null,"abstract":"\u0000 An overview of the response of 2-D woven and 3-D braided SiC/SiC composites to thermomechanical loading up to a temperature of 1300°C is presented. The composites utilize Nicalon SiC fibers and are manufactured by the chemical vapor infiltration process. Fiber architecture controls the damage behavior of the composites both directly and indirectly by determining the sizes and distributions of microstructural pores within and between fiber bundles. The role of porosity on damage evolution is investigated by studying SiC/SiC composites with two porosity levels. A damage mechanics model based on Ladeveze’s approach is used to analyze the damage behavior of the composites. In addition to failure under tension, compression and bending, the fracture behavior of 2-D SiC/SiC composites is characterized through the application of various energy approaches based on the linear elastic fracture mechanics and J-integral methods. The toughness parameters thus obtained are compared and the suitability of the approaches discussed.","PeriodicalId":326220,"journal":{"name":"Aerospace and Materials","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132124891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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