P. Rao, U. Palliyaguru, M. Gurvich, W. Seneviratne
In this work an engineering approach is demonstrated for analyzing damage initiation modes in tapered composite structures. The analysis methodology includes simulation of the non-linear static response of tapered composite structures under static tension loads to predict the location of interfacial delamination initiation. Furthermore, the developed methodology provides a strength-based criterion to assess whether damage initiation will occur in the inter-laminar delamination or intra-laminar matrix cracking mode. Based on the results of the analysis, a tapered composite structure is fabricated and tested under displacement-controlled quasi-static tension loading. The damage initiation location captured experimentally is compared with the analysis towards achieving preliminary qualitative validation. The linear stiffness of the tapered composite structure is predicted within 15% of the experimental average thereby achieving preliminary quantitative validation.
{"title":"An Engineering Approach to Analyze Damage Initiation Modes in Tapered Composite Structures","authors":"P. Rao, U. Palliyaguru, M. Gurvich, W. Seneviratne","doi":"10.12783/ASC33/26098","DOIUrl":"https://doi.org/10.12783/ASC33/26098","url":null,"abstract":"In this work an engineering approach is demonstrated for analyzing damage initiation modes in tapered composite structures. The analysis methodology includes simulation of the non-linear static response of tapered composite structures under static tension loads to predict the location of interfacial delamination initiation. Furthermore, the developed methodology provides a strength-based criterion to assess whether damage initiation will occur in the inter-laminar delamination or intra-laminar matrix cracking mode. Based on the results of the analysis, a tapered composite structure is fabricated and tested under displacement-controlled quasi-static tension loading. The damage initiation location captured experimentally is compared with the analysis towards achieving preliminary qualitative validation. The linear stiffness of the tapered composite structure is predicted within 15% of the experimental average thereby achieving preliminary quantitative validation.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128941680","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 the present study, strain-rate dependence and temperature dependence of failure mode are numerically simulated by finite element analyses. In the analyses, interface failure and matrix failure are expressed by cohesive zone modeling and continuum damage mechanics, respectively. It is assumed that the damage initiates dependently of strain rate and temperature, and cohesive zone modeling is assumed to be temperature- and time-independent. In the continuum damage mechanics, Christensen’s failure criterion of multi-axial stress states for each strain rate are applied into the resin properties. Interfacial strength which is obtained by microbond test is introduced into cohesive zone modeling. When temperature is high and/or strain rate is low, matrix crack occurs very often and the failure mode is matrix-failuredominant mode. On the other hand, when temperature is low and/or strain rate is high, interface crack significant, i.e. failure mode becomes interface-crack-dominant mode.
{"title":"Failure Mode Transition in Transverse Tensile of UD-CFRP Under Various Temperatures and Strain rates","authors":"Mio Sato, Sakie Shirai, J. Koyanagi, Y. Ishida","doi":"10.12783/ASC33/26165","DOIUrl":"https://doi.org/10.12783/ASC33/26165","url":null,"abstract":"In the present study, strain-rate dependence and temperature dependence of failure mode are numerically simulated by finite element analyses. In the analyses, interface failure and matrix failure are expressed by cohesive zone modeling and continuum damage mechanics, respectively. It is assumed that the damage initiates dependently of strain rate and temperature, and cohesive zone modeling is assumed to be temperature- and time-independent. In the continuum damage mechanics, Christensen’s failure criterion of multi-axial stress states for each strain rate are applied into the resin properties. Interfacial strength which is obtained by microbond test is introduced into cohesive zone modeling. When temperature is high and/or strain rate is low, matrix crack occurs very often and the failure mode is matrix-failuredominant mode. On the other hand, when temperature is low and/or strain rate is high, interface crack significant, i.e. failure mode becomes interface-crack-dominant mode.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124676983","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}
W. Rodgers, Praveen Pasupuleti, Selina Zhao, A. Dereims, M. Doroudian, V. Aitharaju
{"title":"Draping Behavior of Non-Crimp Fabrics","authors":"W. Rodgers, Praveen Pasupuleti, Selina Zhao, A. Dereims, M. Doroudian, V. Aitharaju","doi":"10.12783/ASC33/25976","DOIUrl":"https://doi.org/10.12783/ASC33/25976","url":null,"abstract":"","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128632720","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}
{"title":"Investigation of Mode I Crack Growth of VARTM Carbon Composites Using Optical Fibers","authors":"D. A. Drake, R. Sullivan, K. Brown, S. Clay","doi":"10.12783/asc33/26128","DOIUrl":"https://doi.org/10.12783/asc33/26128","url":null,"abstract":"","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128927549","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 closed-form fracture methodology based on first order shear deformable plate theory (FSDT) was developed in Reference [1]. By using a sub-laminate model and adopting transverse shear-deformable laminate theory, general expressions for total strain energy-release rate (SERR) and its individual components were derived. Making use of the first order shear deformable plate theory, closed-form expressions for the calculation of the individual modes of the strain energy release rate for traditional unidirectional laminate test specimens used to obtain fracture toughness properties (Double Cantilever Beam, End Notch Flexure and Mixed-Mode Bending) are presented.
{"title":"Closed-Form Mixed-Mode Strain Energy Release Rate Expressions for Unidirectional Laminate Configurations","authors":"Patrick Enjuto, G. Mabson","doi":"10.12783/ASC33/26094","DOIUrl":"https://doi.org/10.12783/ASC33/26094","url":null,"abstract":"A closed-form fracture methodology based on first order shear deformable plate theory (FSDT) was developed in Reference [1]. By using a sub-laminate model and adopting transverse shear-deformable laminate theory, general expressions for total strain energy-release rate (SERR) and its individual components were derived. Making use of the first order shear deformable plate theory, closed-form expressions for the calculation of the individual modes of the strain energy release rate for traditional unidirectional laminate test specimens used to obtain fracture toughness properties (Double Cantilever Beam, End Notch Flexure and Mixed-Mode Bending) are presented.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125661084","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}
Significant local temperature rises often accompany the high rate deformation of polymer matrix composites. In the case of impact loading, heat is generated locally within the polymer matrix due to plastic dissipation, but the rapid nature of the loading precludes significant heat transfer from occurring; ballistic impact loading can therefore be regarded as fully adiabatic. In this paper, the development of a synergistic multiscale approach to simulate the architecturally dependent impact response of polymer matrix composites with complex fiber tow architectures is presented and applied to a representative triaxially braided composite material system. To approximate the heterogeneity of the composite braid architecture at the highest analysis length scale, a subcell-based approach is utilized whereby the mesoscale repeating unit cell of the material is discretized in-plane into an assemblage of laminated composite subcell regions, with stacking sequences determined from the braid architecture. Each unidirectional layer of the laminated composite subcells are modeled with the generalized method of cells micromechanics theory, where a nonisothermal viscoplastic constitutive model is employed to model the rate, temperature, and pressure dependent polymer matrix. Matrix temperature rises due to inelastic deformation are computed. in matrix elastic properties are determined from neat resin dynamic mechanical analysis data. The commercial transient dynamic finite element code LS-DYNA is utilized to conduct simulations of quasi-static coupon tests and flat panel impact tests performed on a T700/PR520 [0°/60°/–60°] triaxially braided composite. Good agreement is found between simulations and experiments. It is expected that, once progressive damage and failure are incorporated into the multiscale scheme, the incorporation of adiabatic heating affects will greatly improve the predictive capability of current models.
{"title":"Multiscale Modeling of the Impact Response of Triaxially Braided Polymer Matrix Composites, Including Effects of Adiabatic Heating","authors":"C. Sorini, A. Chattopadhyay, R. Goldberg","doi":"10.12783/ASC33/25997","DOIUrl":"https://doi.org/10.12783/ASC33/25997","url":null,"abstract":"Significant local temperature rises often accompany the high rate deformation of polymer matrix composites. In the case of impact loading, heat is generated locally within the polymer matrix due to plastic dissipation, but the rapid nature of the loading precludes significant heat transfer from occurring; ballistic impact loading can therefore be regarded as fully adiabatic. In this paper, the development of a synergistic multiscale approach to simulate the architecturally dependent impact response of polymer matrix composites with complex fiber tow architectures is presented and applied to a representative triaxially braided composite material system. To approximate the heterogeneity of the composite braid architecture at the highest analysis length scale, a subcell-based approach is utilized whereby the mesoscale repeating unit cell of the material is discretized in-plane into an assemblage of laminated composite subcell regions, with stacking sequences determined from the braid architecture. Each unidirectional layer of the laminated composite subcells are modeled with the generalized method of cells micromechanics theory, where a nonisothermal viscoplastic constitutive model is employed to model the rate, temperature, and pressure dependent polymer matrix. Matrix temperature rises due to inelastic deformation are computed. in matrix elastic properties are determined from neat resin dynamic mechanical analysis data. The commercial transient dynamic finite element code LS-DYNA is utilized to conduct simulations of quasi-static coupon tests and flat panel impact tests performed on a T700/PR520 [0°/60°/–60°] triaxially braided composite. Good agreement is found between simulations and experiments. It is expected that, once progressive damage and failure are incorporated into the multiscale scheme, the incorporation of adiabatic heating affects will greatly improve the predictive capability of current models.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127160399","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}
Aniruddh Vashisth, Chowdhury M. Ashraf, C. Bakis, A. Duin
Molecular dynamics simulations of polymers can help in understanding the dependence of molecular structure, cross-linking and the chemistry of the polymer chain and resulting thermo-mechanical properties of the polymer. Apart from these thermo-mechanical properties, molecular dynamics is also a powerful tool to examine the durability of polymers with potential aerospace applications under harsh environmental conditions. Ultraviolent radiation from the sun results in dissociation of molecular oxygen into atomic oxygen (AO) which is abundant in lower earth orbit. Testing composites under AO impact requires an extensive experimental setup to simulate low earth orbit (LEO) conditions and is therefore expensive. Using a newly developed accelerated cross-linking methodology in the framework of ReaxFF, bisphenol F and diethyltoluenediamine epoxy polymer chains are manufactured virtually. This simulated polymer is virtually tested for modulus, glass transition temperature, density and is impacted by atomic oxygen at 8 km/s. Thermomechanical properties show good agreement between experiments and simulations. Simulations the polymer during AO impact using ReaxFF provides useful insight to the degradation mechanism in terms of polymer chemistry and thermal profile.
聚合物的分子动力学模拟有助于了解分子结构、交联和聚合物链的化学性质与聚合物热机械特性之间的关系。除了这些热机械特性外，分子动力学还是一种强大的工具，可用于研究在恶劣环境条件下具有航空航天应用潜力的聚合物的耐久性。来自太阳的超强辐射会导致分子氧解离成原子氧（AO），而原子氧在低地球轨道中含量丰富。测试复合材料是否受到原子氧的影响需要大量的实验装置来模拟低地球轨道（LEO）条件，因此成本高昂。利用 ReaxFF 框架内新开发的加速交联方法，可以虚拟制造双酚 F 和二乙基甲苯二胺环氧聚合物链。对这种模拟聚合物的模量、玻璃化转变温度和密度进行了虚拟测试，并以 8 千米/秒的速度对其进行了原子氧冲击。实验和模拟结果的热力学特性非常吻合。使用 ReaxFF 模拟聚合物在受到原子氧撞击时的降解过程，有助于深入了解聚合物的化学性质和热特性。
{"title":"Reactive Molecular Dynamics Simulation of Accelerated Cross-linking and Disintegration of Bisphenol F/DETDA Polymer using ReaxFF","authors":"Aniruddh Vashisth, Chowdhury M. Ashraf, C. Bakis, A. Duin","doi":"10.12783/ASC33/25939","DOIUrl":"https://doi.org/10.12783/ASC33/25939","url":null,"abstract":"Molecular dynamics simulations of polymers can help in understanding the dependence of molecular structure, cross-linking and the chemistry of the polymer chain and resulting thermo-mechanical properties of the polymer. Apart from these thermo-mechanical properties, molecular dynamics is also a powerful tool to examine the durability of polymers with potential aerospace applications under harsh environmental conditions. Ultraviolent radiation from the sun results in dissociation of molecular oxygen into atomic oxygen (AO) which is abundant in lower earth orbit. Testing composites under AO impact requires an extensive experimental setup to simulate low earth orbit (LEO) conditions and is therefore expensive. Using a newly developed accelerated cross-linking methodology in the framework of ReaxFF, bisphenol F and diethyltoluenediamine epoxy polymer chains are manufactured virtually. This simulated polymer is virtually tested for modulus, glass transition temperature, density and is impacted by atomic oxygen at 8 km/s. Thermomechanical properties show good agreement between experiments and simulations. Simulations the polymer during AO impact using ReaxFF provides useful insight to the degradation mechanism in terms of polymer chemistry and thermal profile.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"97 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127219191","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 triangular rollable and collapsible (TRAC) boom is an attractive architecture for deployable spacecraft structures due to its minimal flattened height-to-deployed stiffness ratio. A challenge for TRAC booms however is the development of a buckling mode that occurs (on the inner flange) when furling the boom around a hub for stowage. In this research, the buckling mode was found to be sensitive to boom flange length and the composite flexural stiffnesses dictated by the laminate materials, fiber orientations and ply stacking sequence. Finite element studies were performed to investigate the influence of flange arc length and composite layup on critical stresses and strains prompted by the buckled wave. Longer flange lengths resulted in higher strains but could be offset through modifications to the laminate architecture allowing for larger booms to be packaged without increasing the minimum stowage (hub) diameter. The analysis model was validated through experimental furling tests and successful correlation between the simulation strains and experimental strain gages.
{"title":"An Investigation of Inner Flange Buckling in Furlable Composite Booms","authors":"K. Cox, Kamron A. Medina","doi":"10.12783/ASC33/26162","DOIUrl":"https://doi.org/10.12783/ASC33/26162","url":null,"abstract":"The triangular rollable and collapsible (TRAC) boom is an attractive architecture for deployable spacecraft structures due to its minimal flattened height-to-deployed stiffness ratio. A challenge for TRAC booms however is the development of a buckling mode that occurs (on the inner flange) when furling the boom around a hub for stowage. In this research, the buckling mode was found to be sensitive to boom flange length and the composite flexural stiffnesses dictated by the laminate materials, fiber orientations and ply stacking sequence. Finite element studies were performed to investigate the influence of flange arc length and composite layup on critical stresses and strains prompted by the buckled wave. Longer flange lengths resulted in higher strains but could be offset through modifications to the laminate architecture allowing for larger booms to be packaged without increasing the minimum stowage (hub) diameter. The analysis model was validated through experimental furling tests and successful correlation between the simulation strains and experimental strain gages.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127450843","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 objective of this paper is to develop a continuum damage model for fatigue prediction. A viscodamage model, which can rigorously handle damage anisotropy, distinct tensile and compressive damage behavior, and damage deactivation, is developed to produce stress-dependent fatigue damage evolution. An affine formulation governing damage evolution, and a closed-form formulation of the constitutive relations is derived based on the viscodamage model. An adaptive stepsize control and cycle jump time integration scheme is proposed and implemented to improve the present model’s efficiency in cyclic loading conditions. Through uniaxial cyclic loading simulations, the present model and time integration scheme is found to be capable of reliably and efficiently producing cyclic damage evolution. This model can be further calibrated to facilitate both uniaxial and multiaxial fatigue analysis in composite materials.
{"title":"A Continuum Damage Model for Fatigue and Its Integration Scheme","authors":"Z. Gao, Liang Zhang, R. Haynes, Wenbin Yu","doi":"10.12783/ASC33/26169","DOIUrl":"https://doi.org/10.12783/ASC33/26169","url":null,"abstract":"The objective of this paper is to develop a continuum damage model for fatigue prediction. A viscodamage model, which can rigorously handle damage anisotropy, distinct tensile and compressive damage behavior, and damage deactivation, is developed to produce stress-dependent fatigue damage evolution. An affine formulation governing damage evolution, and a closed-form formulation of the constitutive relations is derived based on the viscodamage model. An adaptive stepsize control and cycle jump time integration scheme is proposed and implemented to improve the present model’s efficiency in cyclic loading conditions. Through uniaxial cyclic loading simulations, the present model and time integration scheme is found to be capable of reliably and efficiently producing cyclic damage evolution. This model can be further calibrated to facilitate both uniaxial and multiaxial fatigue analysis in composite materials.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127068845","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 the present work, an overview is presented on the recent work carried out by the authors on the influence of manufacturing-induced porosity on the long-term performances of composite materials. The effect of voids was first studied in terms of fatigue damage mechanisms at the micro-scale. An extensive experimental campaign was then carried out to assess the effect of porosity on the life to crack initiation (S-N curves), crack propagation (Paris curve), crack density evolution and global stiffness drop of [0/902]S and [0/452/0/-452]S laminates. Finally, a model that allows to predict the life to crack initiation from the behaviour of the void-free material was developed, showing good accordance with the experimental results.
{"title":"Effect of Manufacturing-Induced Voids on the Fatigue Performances of Multidirectional Laminates","authors":"M. Quaresimin, L. Maragoni, P. Carraro","doi":"10.12783/ASC33/25994","DOIUrl":"https://doi.org/10.12783/ASC33/25994","url":null,"abstract":"In the present work, an overview is presented on the recent work carried out by the authors on the influence of manufacturing-induced porosity on the long-term performances of composite materials. The effect of voids was first studied in terms of fatigue damage mechanisms at the micro-scale. An extensive experimental campaign was then carried out to assess the effect of porosity on the life to crack initiation (S-N curves), crack propagation (Paris curve), crack density evolution and global stiffness drop of [0/902]S and [0/452/0/-452]S laminates. Finally, a model that allows to predict the life to crack initiation from the behaviour of the void-free material was developed, showing good accordance with the experimental results.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"157 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122450402","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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