Castings usually contain defects such as shrinkage cavities and internal gas porosity. The application of hot isostatic pressing (HIPping) to cast metals can remove such defects through the synergistic effect of high isostatic pressure and high temperature. This paper investigates the effects of HIPping on creep of cast A359/SiC/20p composite. Although creep life was expected to improve due to removal of internal porosity in the castings, the creep results were contrary to expectations. Activation energy calculated for the cast composite, showed a decrease in activation energy for the material after HIPping. Creep life was noted to have improved with higher tensile strength as for the cast composite while creep strain at failure improved with an increase in elongation for the cast-HIPped composite. The effect of stress on creep properties are reported to show a decrease in creep life and creep strain at failure with an increase in stress, temperature remaining constant.
{"title":"Creep Behaviour of Hot Isostatically Pressed Metal-Matrix Composite","authors":"C. S. Lim, N. P. Hung, Y. C. Tan, N. Loh","doi":"10.1115/imece1996-0496","DOIUrl":"https://doi.org/10.1115/imece1996-0496","url":null,"abstract":"\u0000 Castings usually contain defects such as shrinkage cavities and internal gas porosity. The application of hot isostatic pressing (HIPping) to cast metals can remove such defects through the synergistic effect of high isostatic pressure and high temperature. This paper investigates the effects of HIPping on creep of cast A359/SiC/20p composite. Although creep life was expected to improve due to removal of internal porosity in the castings, the creep results were contrary to expectations. Activation energy calculated for the cast composite, showed a decrease in activation energy for the material after HIPping. Creep life was noted to have improved with higher tensile strength as for the cast composite while creep strain at failure improved with an increase in elongation for the cast-HIPped composite. The effect of stress on creep properties are reported to show a decrease in creep life and creep strain at failure with an increase in stress, temperature remaining constant.","PeriodicalId":326220,"journal":{"name":"Aerospace and Materials","volume":"12 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":"131921095","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}
P. Mclaughlin, Henry A. McShane, R. Cochran, E. Armstrong-Carroll
An analysis of local fiber/matrix interface damage growth in unidirectional composites under tension-tension loading is modified to include thermal residual stresses and subsequent temperature histories with the goal of estimating the loss of strength and fatigue life occurring when a graphite/epoxy composite structure is subjected to flame or hot exhaust gasses. Tests show that epoxy thermomechanical and strength properties degrade rapidly from 200 to 300°C, and that time-at-temperature is important. Using properties estimated from these tests, two mechanisms of static strength and fatigue life reduction are studied: thermal-stress-induced interface cracking parallel to fibers, and degradation of room-temperature interface properties. The effects of heat on static strength and constant-amplitude fatigue life of a particular graphite/epoxy material system are then analytically determined for two heat exposure scenarios: one, a relatively short-time exposure of five minutes; and two, a long-time exposure of more than an hour. Strength and life loss are found to be dependent on temperature, time-at-temperature, and length of damage zone, with severe reductions in static and fatigue strengths at temperatures above 200°C.
{"title":"Effects of High Heat on the Strength and Fatigue Life of Unidirectional Polymer-Matrix Composites","authors":"P. Mclaughlin, Henry A. McShane, R. Cochran, E. Armstrong-Carroll","doi":"10.1115/imece1996-0495","DOIUrl":"https://doi.org/10.1115/imece1996-0495","url":null,"abstract":"\u0000 An analysis of local fiber/matrix interface damage growth in unidirectional composites under tension-tension loading is modified to include thermal residual stresses and subsequent temperature histories with the goal of estimating the loss of strength and fatigue life occurring when a graphite/epoxy composite structure is subjected to flame or hot exhaust gasses. Tests show that epoxy thermomechanical and strength properties degrade rapidly from 200 to 300°C, and that time-at-temperature is important. Using properties estimated from these tests, two mechanisms of static strength and fatigue life reduction are studied: thermal-stress-induced interface cracking parallel to fibers, and degradation of room-temperature interface properties. The effects of heat on static strength and constant-amplitude fatigue life of a particular graphite/epoxy material system are then analytically determined for two heat exposure scenarios: one, a relatively short-time exposure of five minutes; and two, a long-time exposure of more than an hour. Strength and life loss are found to be dependent on temperature, time-at-temperature, and length of damage zone, with severe reductions in static and fatigue strengths at temperatures above 200°C.","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":"123806765","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}
Titanium Matrix Composites (TMC’s) like SCS-6/Timetal 21S are envisioned for use as a structural material for advanced aircraft and in the next generation of turbine engine. In general, damage in representative temperature and load regimes can be dominated by either mechanical, environmental or time dependent deformation and damage mechanisms. Mechanical deformation, present under all load conditions, includes mechanisms such as matrix yielding and fiber/matrix debonding. Time dependent deformation refers to either the creep or relaxation of the matrix and will typically occur at moderately high elevated temperatures. Environmental damage is also time dependent but is distinguished by the fact that it describes the chemical interaction of the composite and the environment. Environmental damage in SCS-6/Timetal 21S composites is commonly thought to be caused by the oxygen embrittlement of the matrix. This damage type becomes prevalent at high elevated temperatures which are near the operational limit of the material. Testing has been completed at Georgia Tech to separate the three damage types listed above. This test matrix involved isothermal constant amplitude fatigue tests at temperatures of 400, 500 and 650°C with hold times at the maximum stress varying from 1 to 100 seconds. Testing was conducted on laminates with stacking sequences of both [0/±45/90]s and [90/±45/0]s. The changes in stacking sequence yielded significant differences in cyclic lives for identical test conditions. Fractographic examination of the specimens indicate that the true cause for environmental attack is not the formation of brittle oxides, but the coarsening of the alpha grains in the microstructure. This form of damage is shown to affect the fracture morphology of specimens at all temperatures, but proper selection of the stacking sequence can reduce the importance of this effect and increase cyclic lives.
{"title":"Microscopic Examination of Titanium Matrix Composites Subjected to Testing Designed to Cause Varying Dominant Damage Mechanisms","authors":"J. Calcaterra, W. S. Johnson","doi":"10.1115/imece1996-0476","DOIUrl":"https://doi.org/10.1115/imece1996-0476","url":null,"abstract":"\u0000 Titanium Matrix Composites (TMC’s) like SCS-6/Timetal 21S are envisioned for use as a structural material for advanced aircraft and in the next generation of turbine engine. In general, damage in representative temperature and load regimes can be dominated by either mechanical, environmental or time dependent deformation and damage mechanisms. Mechanical deformation, present under all load conditions, includes mechanisms such as matrix yielding and fiber/matrix debonding. Time dependent deformation refers to either the creep or relaxation of the matrix and will typically occur at moderately high elevated temperatures. Environmental damage is also time dependent but is distinguished by the fact that it describes the chemical interaction of the composite and the environment. Environmental damage in SCS-6/Timetal 21S composites is commonly thought to be caused by the oxygen embrittlement of the matrix. This damage type becomes prevalent at high elevated temperatures which are near the operational limit of the material. Testing has been completed at Georgia Tech to separate the three damage types listed above. This test matrix involved isothermal constant amplitude fatigue tests at temperatures of 400, 500 and 650°C with hold times at the maximum stress varying from 1 to 100 seconds. Testing was conducted on laminates with stacking sequences of both [0/±45/90]s and [90/±45/0]s. The changes in stacking sequence yielded significant differences in cyclic lives for identical test conditions. Fractographic examination of the specimens indicate that the true cause for environmental attack is not the formation of brittle oxides, but the coarsening of the alpha grains in the microstructure. This form of damage is shown to affect the fracture morphology of specimens at all temperatures, but proper selection of the stacking sequence can reduce the importance of this effect and increase cyclic lives.","PeriodicalId":326220,"journal":{"name":"Aerospace and Materials","volume":"83 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":"127106992","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}
Spallation is a major failure condition experienced by thermal barrier coatings (TBCs) subjected to thermal and mechanical loads. Although evidence of spallation is substantiated and mechanistic models to describe the failure condition is prevalent in literature, the progressive nature of damage evolution leading to spallation has not been addressed adequately. In this paper, we investigated the damage evolution in partially stabilized zirconia TBC on Nickel-based single crystal superalloy, Rene N5. Thermal cycles were imposed on button specimens with Electron Beam - Plasma Vapor Deposition (EB-PVD) TBC coating. The bond coat was PtAl. The temperature range used was 200–1177C. Progressive damage evolution was tracked using microscopy on samples subjected to a series of thermal cycles. Fick’s law can describe the thermally grown oxide (TGO) buildup for early cycles. However, at higher number of thermal cycles, damage in the form of microcracks and their coalescence results in the loss of integrity of the TGO. Thus, both oxidation kinetics and damage appears to have significant roles to play as it relates to spallation. As these microcracks coalesce to form major delamination cracks or interlayer separation, the susceptibility for coating buckling is increased. The delamination cracks finally consume the TGO layer. The loss of TBC integrity from the bond coat and the substrate facilitates its buckling during cool down from elevated temperature. Our estimations show that a delamination crack length of about sixteen times the TBC thickness is needed for the current material system to initiate buckling. Progressive microcrack linking is a possible mechanism to develop such critical delamination crack lengths. Physical evidence of buckling was found in specimens prior to complete spallation.
{"title":"Damage Accumulation Mechanisms in Thermal Barrier Coatings","authors":"G. Newaz, S. Nusier, Z. Chaudhury","doi":"10.1115/1.2807004","DOIUrl":"https://doi.org/10.1115/1.2807004","url":null,"abstract":"\u0000 Spallation is a major failure condition experienced by thermal barrier coatings (TBCs) subjected to thermal and mechanical loads. Although evidence of spallation is substantiated and mechanistic models to describe the failure condition is prevalent in literature, the progressive nature of damage evolution leading to spallation has not been addressed adequately. In this paper, we investigated the damage evolution in partially stabilized zirconia TBC on Nickel-based single crystal superalloy, Rene N5. Thermal cycles were imposed on button specimens with Electron Beam - Plasma Vapor Deposition (EB-PVD) TBC coating. The bond coat was PtAl. The temperature range used was 200–1177C. Progressive damage evolution was tracked using microscopy on samples subjected to a series of thermal cycles. Fick’s law can describe the thermally grown oxide (TGO) buildup for early cycles. However, at higher number of thermal cycles, damage in the form of microcracks and their coalescence results in the loss of integrity of the TGO. Thus, both oxidation kinetics and damage appears to have significant roles to play as it relates to spallation. As these microcracks coalesce to form major delamination cracks or interlayer separation, the susceptibility for coating buckling is increased. The delamination cracks finally consume the TGO layer. The loss of TBC integrity from the bond coat and the substrate facilitates its buckling during cool down from elevated temperature. Our estimations show that a delamination crack length of about sixteen times the TBC thickness is needed for the current material system to initiate buckling. Progressive microcrack linking is a possible mechanism to develop such critical delamination crack lengths. Physical evidence of buckling was found in specimens prior to complete spallation.","PeriodicalId":326220,"journal":{"name":"Aerospace and Materials","volume":"278 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":"124473277","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 evolution of microstructural damage during fatigue loading, which includes matrix cracking, interfacial debonding, and fiber fracture results in the progressive degradation of mechanical properties of the fiber-reinforced titanium matrix composites. A mechanism-based fatigue life prediction methodology was developed to simulate the evolution of fatigue damage, degradation of mechanical properties, and distribution of fatigue lives under various applied stress levels. The simulated matrix crack propagation rates, residual stiffness, residual tensile strength, and fatigue life are also correlated with experimental results.
{"title":"Fatigue Damage Modeling and Life Prediction of Titanium Matrix Composites","authors":"P. C. Wang, J. Yang, A. Mal","doi":"10.1115/imece1996-0472","DOIUrl":"https://doi.org/10.1115/imece1996-0472","url":null,"abstract":"\u0000 The evolution of microstructural damage during fatigue loading, which includes matrix cracking, interfacial debonding, and fiber fracture results in the progressive degradation of mechanical properties of the fiber-reinforced titanium matrix composites. A mechanism-based fatigue life prediction methodology was developed to simulate the evolution of fatigue damage, degradation of mechanical properties, and distribution of fatigue lives under various applied stress levels. The simulated matrix crack propagation rates, residual stiffness, residual tensile strength, and fatigue life are also correlated with experimental results.","PeriodicalId":326220,"journal":{"name":"Aerospace and Materials","volume":"225 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":"122854392","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 new dislocation punching model for a functionally graded material (FGM) subjected to a temperature change has been proposed, using Eshelby’s model. FGM, consisting of several layers, is deposited on a ceramic substrate. Two types of microstructures are examined for a layer: one consists of a metal matrix and ceramic particles and the other of a ceramic matrix and metal particles. An elastic energy is evaluated when plastic strain, in addition to thermal mismatch strain, is introduced in the metal phase. The work dissipated by the plastic deformation is also calculated. From the condition that the reduction in the elastic energy is larger than the work dissipated, a critical thermal mismatch strain to induce stress relaxation is determined. The magnitude of the plastic strain is also determined, when the relaxation occurs. The results of the present theory for a special case of FGM, i.e., the case of single interface coincide with those of our earlier work on a thin metal coating on ceramic substrate. The theory is applied to a model FGM consisting of mixtures of Pd and Al2O3 on an Al2O3 substrate.
{"title":"Dislocation Punching in Functionally-Graded Materials","authors":"M. Taya, J. Lee, T. Mori","doi":"10.1115/imece1996-0473","DOIUrl":"https://doi.org/10.1115/imece1996-0473","url":null,"abstract":"\u0000 A new dislocation punching model for a functionally graded material (FGM) subjected to a temperature change has been proposed, using Eshelby’s model. FGM, consisting of several layers, is deposited on a ceramic substrate. Two types of microstructures are examined for a layer: one consists of a metal matrix and ceramic particles and the other of a ceramic matrix and metal particles. An elastic energy is evaluated when plastic strain, in addition to thermal mismatch strain, is introduced in the metal phase. The work dissipated by the plastic deformation is also calculated. From the condition that the reduction in the elastic energy is larger than the work dissipated, a critical thermal mismatch strain to induce stress relaxation is determined. The magnitude of the plastic strain is also determined, when the relaxation occurs. The results of the present theory for a special case of FGM, i.e., the case of single interface coincide with those of our earlier work on a thin metal coating on ceramic substrate. The theory is applied to a model FGM consisting of mixtures of Pd and Al2O3 on an Al2O3 substrate.","PeriodicalId":326220,"journal":{"name":"Aerospace and Materials","volume":"63 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":"115980964","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}
In this work, we will consider the three most crucial mechanisms that control the behavior of unidirectional brittle matrix composites (BMC) such that they display the desired characteristics of adequate strength and damage tolerance (or toughness). Composites made with uncoated silicon carbide fibers and two different glass matrices which differ principally in their thermal expansion coefficients were made and tested in order to determine matrix crack initiation stress (Fig. 1), fiber fracture (Fig. 2), and a lower bound interface fracture toughness (Fig. 3). Furthermore, these tests provide direct evidence to examine the quality of an axisymmetric damage model (ADM) derived earlier [1, 2]. Although there was no observed damage tolerance in that both stress-strain curves were linear to failure, a stable system of (apparently) full-cell matrix cracks (Fig. 1) develops prior to ultimate failure. It is not clear if the matrix cracks have arrested prior to entering the fiber or if they have penetrated the fiber itself.
{"title":"Crack Deflection and Penetration Criteria for Brittle Matrix Composites","authors":"N. Pagano","doi":"10.1115/imece1996-0479","DOIUrl":"https://doi.org/10.1115/imece1996-0479","url":null,"abstract":"\u0000 In this work, we will consider the three most crucial mechanisms that control the behavior of unidirectional brittle matrix composites (BMC) such that they display the desired characteristics of adequate strength and damage tolerance (or toughness). Composites made with uncoated silicon carbide fibers and two different glass matrices which differ principally in their thermal expansion coefficients were made and tested in order to determine matrix crack initiation stress (Fig. 1), fiber fracture (Fig. 2), and a lower bound interface fracture toughness (Fig. 3). Furthermore, these tests provide direct evidence to examine the quality of an axisymmetric damage model (ADM) derived earlier [1, 2]. Although there was no observed damage tolerance in that both stress-strain curves were linear to failure, a stable system of (apparently) full-cell matrix cracks (Fig. 1) develops prior to ultimate failure. It is not clear if the matrix cracks have arrested prior to entering the fiber or if they have penetrated the fiber itself.","PeriodicalId":326220,"journal":{"name":"Aerospace and Materials","volume":"20 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":"126753306","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}
S. Adjerid, M. Beall, G. Dvorak, J. Fish, J. Flaherty, J. Hudson, K. Shek, M. Shephard, R. Wentorf
The paper introduces high temperature composite software developed for mechanism-based design of composite structures. Mechanism-based design is characterized by an understanding of the critical composite behaviors at several physical scales: the fibrous (micro) scale, the ply/weave (meso) scale and the laminated part (macro) scale, and by the specification of the available design parameters to achieve functionality by those behaviors. A software framework is described which integrates material modeling and analysis codes, provides automated assistance, and links to material databases. Elastic and inelastic material modeling codes suitable for high temperature composites with complex reinforcement and weave/lay-up configurations are presented and references to their underlying theories are given. Advanced analysis techniques are outlined for numerically efficient computational plasticity based on mathematical homogenization, idealization error indicators for material scale, three dimensional crack propagation in a fibrous composite, and modeling of reactive vapor infiltration and chemical vapor deposition processes.
{"title":"Mechanism-Based Design of Composite Structures","authors":"S. Adjerid, M. Beall, G. Dvorak, J. Fish, J. Flaherty, J. Hudson, K. Shek, M. Shephard, R. Wentorf","doi":"10.1115/imece1996-0485","DOIUrl":"https://doi.org/10.1115/imece1996-0485","url":null,"abstract":"\u0000 The paper introduces high temperature composite software developed for mechanism-based design of composite structures. Mechanism-based design is characterized by an understanding of the critical composite behaviors at several physical scales: the fibrous (micro) scale, the ply/weave (meso) scale and the laminated part (macro) scale, and by the specification of the available design parameters to achieve functionality by those behaviors. A software framework is described which integrates material modeling and analysis codes, provides automated assistance, and links to material databases. Elastic and inelastic material modeling codes suitable for high temperature composites with complex reinforcement and weave/lay-up configurations are presented and references to their underlying theories are given. Advanced analysis techniques are outlined for numerically efficient computational plasticity based on mathematical homogenization, idealization error indicators for material scale, three dimensional crack propagation in a fibrous composite, and modeling of reactive vapor infiltration and chemical vapor deposition processes.","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":"127057882","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}
Traditional methods of viscoelastic material characterization have not been able to rapidly characterize nonlinear viscoelastic materials. Dynamic mechanical analysis has been a method in which only linear viscoelastic material properties are rapidly identifying. Herein, dynamic mechanical analysis is extended to provide a method of nonlinear characterization. The proposed method is based on an extension of Schapery’s nonlinear viscoelastic model to dynamic mechanical theory. The oscillatory loading during a dynamic test is accounted for by expanding the nonlinear viscoelastic model on stress. An experimental protocol is established and utilized in the characterization of thin film polyethylene for validation of the nonlinear dynamic mechanical theory.
{"title":"An Approach to Characterize Nonlinear Viscoelastic Material Behavior Using Dynamic Mechanical Tests and Analyses","authors":"H. Golden, T. Strganac, Richard Schapery","doi":"10.1115/1.2791791","DOIUrl":"https://doi.org/10.1115/1.2791791","url":null,"abstract":"\u0000 Traditional methods of viscoelastic material characterization have not been able to rapidly characterize nonlinear viscoelastic materials. Dynamic mechanical analysis has been a method in which only linear viscoelastic material properties are rapidly identifying. Herein, dynamic mechanical analysis is extended to provide a method of nonlinear characterization. The proposed method is based on an extension of Schapery’s nonlinear viscoelastic model to dynamic mechanical theory. The oscillatory loading during a dynamic test is accounted for by expanding the nonlinear viscoelastic model on stress. An experimental protocol is established and utilized in the characterization of thin film polyethylene for validation of the nonlinear dynamic mechanical theory.","PeriodicalId":326220,"journal":{"name":"Aerospace and Materials","volume":"69 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":"132046301","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}
Failure criteria of fiber reinforced composites expressed in terms of externally applied stresses are derived based on the interface stress distribution. The composite is modeled by a single inclusion surrounded by a matrix which possesses the properties of the composite. Using the Eshelby’s method and the self-consistent approximation, the interface stress can be derived analytically as a function of fiber and matrix properties and the fiber volume fraction. Using the proposed method, failure envelopes can be drawn that can properly reflect the effect of fiber shapes and anisotropy.
{"title":"Failure Analysis of Fiber Composites at Phase Interface","authors":"H. Edmiston, S. Nomura","doi":"10.1115/imece1996-0490","DOIUrl":"https://doi.org/10.1115/imece1996-0490","url":null,"abstract":"\u0000 Failure criteria of fiber reinforced composites expressed in terms of externally applied stresses are derived based on the interface stress distribution. The composite is modeled by a single inclusion surrounded by a matrix which possesses the properties of the composite. Using the Eshelby’s method and the self-consistent approximation, the interface stress can be derived analytically as a function of fiber and matrix properties and the fiber volume fraction. Using the proposed method, failure envelopes can be drawn that can properly reflect the effect of fiber shapes and anisotropy.","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":"132047657","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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