I. Hyder, F. Leone, B. Justusson, J. Schaefer, A. Bergan, S. Wanthal
Continuum Damage Mechanics (CDM) based progressive damage and failure analysis (PDFA) methods have demonstrated success in a variety of finite element analysis (FEA) implementations. However, the technical maturity of CDM codes has not yet been proven for the full design space of composite materials in aerospace applications. CDM-based approaches represent the presence of damage by changing the local material stiffness definitions and without updating the original mesh or element integration schemes. Without discretely representing cracks and their paths through the mesh, damage in models with CDM-based materials is often distributed in a region of partially damaged elements ahead of stress concentrations. Having a series of discrete matrix cracks represented by a softened region may affect predictions of damage propagation and, thus, structural failure. This issue can be mitigated by restricting matrix damage development to discrete, fiber-aligned rows of elements; hence CDM-based matrix cracks can be implemented to be more representative of discrete matrix cracks. This paper evaluates the effect of restricting CDM matrix crack development to discrete, fiber-aligned rows where the spacing of these rows is controlled by a user-defined crack spacing parameter. Initially, the effect of incrementally increasing matrix crack spacing in a unidirectional center notch coupon is evaluated. Then, the lessons learned from the center notch specimen are applied to open-hole compression finite element models. Results are compared to test data, and the limitations, successes, and potential of the matrix crack spacing approach are discussed.
{"title":"Implementation of a Matrix Crack Spacing Parameter in a Continuum Damage Mechanics Finite Element Model","authors":"I. Hyder, F. Leone, B. Justusson, J. Schaefer, A. Bergan, S. Wanthal","doi":"10.12783/ASC33/26052","DOIUrl":"https://doi.org/10.12783/ASC33/26052","url":null,"abstract":"Continuum Damage Mechanics (CDM) based progressive damage and failure analysis (PDFA) methods have demonstrated success in a variety of finite element analysis (FEA) implementations. However, the technical maturity of CDM codes has not yet been proven for the full design space of composite materials in aerospace applications. CDM-based approaches represent the presence of damage by changing the local material stiffness definitions and without updating the original mesh or element integration schemes. Without discretely representing cracks and their paths through the mesh, damage in models with CDM-based materials is often distributed in a region of partially damaged elements ahead of stress concentrations. Having a series of discrete matrix cracks represented by a softened region may affect predictions of damage propagation and, thus, structural failure. This issue can be mitigated by restricting matrix damage development to discrete, fiber-aligned rows of elements; hence CDM-based matrix cracks can be implemented to be more representative of discrete matrix cracks. This paper evaluates the effect of restricting CDM matrix crack development to discrete, fiber-aligned rows where the spacing of these rows is controlled by a user-defined crack spacing parameter. Initially, the effect of incrementally increasing matrix crack spacing in a unidirectional center notch coupon is evaluated. Then, the lessons learned from the center notch specimen are applied to open-hole compression finite element models. Results are compared to test data, and the limitations, successes, and potential of the matrix crack spacing approach are discussed.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"17 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":"129969719","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":"Contamination Transfer from Processing Aid Materials to Prepreg","authors":"A. Suzuki, S. Aoki, Noriko Yamazaki","doi":"10.12783/asc33/25986","DOIUrl":"https://doi.org/10.12783/asc33/25986","url":null,"abstract":"","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"5 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":"130034287","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}
Bodiuzzaman Jony, M. Thapa, Sameer B. Mulani, Samit Roy
A repetitive in-situ healing system for fiber reinforced polymer composite is being developed by incorporating the thermoplastic polycaprolactone (CAPA) healing agent (healent) and shape memory polymer in a thermoset epoxy (SC-780) system. Doublecantilever beam (DCB) specimens with embedded healant were repeatedly fractured and healed by heating above the melting temperature of CAPA (58-60°C). In-situ macro fiber composite (MFC) actuated heating/healing of the fractured specimens was performed by applying a voltage to MFC in the range of 200 to 250 V with 4 kHz excitation frequency for 2 hours to generate 80°C at MFC locations. Heating of the DCB specimens, followed by 24 hours cooling at room temperature yielded as much as 81 % recovery of the virgin interlaminar fracture toughness for different healing cycles, which is close to the maximum healing efficiency (86 %) of conventional oven heating for 2 hours at 80°C. The effect of variation of heating time and other heating parameters are also reported. A parametric study of healing efficiency as a function of heating time showed the effective healing with only twenty minutes of MFC actuated heating was obtained. Scanning electron microscope and optical microscope were also used to qualitatively analyze the fracture surfaces to understand the mechanisms responsible for repetitive self-healing.
{"title":"Repeatability of Non-autonomous Self-Healing with Thermoplastic Healing Agent in Fiber Reinforced Thermoset Composite","authors":"Bodiuzzaman Jony, M. Thapa, Sameer B. Mulani, Samit Roy","doi":"10.12783/ASC33/26147","DOIUrl":"https://doi.org/10.12783/ASC33/26147","url":null,"abstract":"A repetitive in-situ healing system for fiber reinforced polymer composite is being developed by incorporating the thermoplastic polycaprolactone (CAPA) healing agent (healent) and shape memory polymer in a thermoset epoxy (SC-780) system. Doublecantilever beam (DCB) specimens with embedded healant were repeatedly fractured and healed by heating above the melting temperature of CAPA (58-60°C). In-situ macro fiber composite (MFC) actuated heating/healing of the fractured specimens was performed by applying a voltage to MFC in the range of 200 to 250 V with 4 kHz excitation frequency for 2 hours to generate 80°C at MFC locations. Heating of the DCB specimens, followed by 24 hours cooling at room temperature yielded as much as 81 % recovery of the virgin interlaminar fracture toughness for different healing cycles, which is close to the maximum healing efficiency (86 %) of conventional oven heating for 2 hours at 80°C. The effect of variation of heating time and other heating parameters are also reported. A parametric study of healing efficiency as a function of heating time showed the effective healing with only twenty minutes of MFC actuated heating was obtained. Scanning electron microscope and optical microscope were also used to qualitatively analyze the fracture surfaces to understand the mechanisms responsible for repetitive self-healing.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"16 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":"130532281","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}
B. Denos, Sergii G. Kravchenko, D. Sommer, A. Favaloro, R. Pipes, W. Avery
Prepreg platelet molding compounds (PPMCs) are utilized in a growing number of composite applications where parts with complex geometry require both a moderate degree of processability and performance. In collaboration with Boeing Commercial Airplanes, a research group at Purdue University has developed a comprehensive framework for the analysis of process-structure-property-performance relationship of PPMC material systems. The research team focused on non-destructive inspection, multi-scale performance analysis, and molding flow simulation utilizing a complementary set of commercial and research tools that aid in design and understanding of PPMC materials and structures. The lessons learned from each approach about required degree of orientation information, variability in fiber orientation state, variability in performance, and best practices for modeling PPMC systems should be utilized wherever possible and added to as inspection and simulation technologies improve.
{"title":"Prepreg Platelet Molded Composites Process and Performance Analysis","authors":"B. Denos, Sergii G. Kravchenko, D. Sommer, A. Favaloro, R. Pipes, W. Avery","doi":"10.12783/ASC33/25912","DOIUrl":"https://doi.org/10.12783/ASC33/25912","url":null,"abstract":"Prepreg platelet molding compounds (PPMCs) are utilized in a growing number of composite applications where parts with complex geometry require both a moderate degree of processability and performance. In collaboration with Boeing Commercial Airplanes, a research group at Purdue University has developed a comprehensive framework for the analysis of process-structure-property-performance relationship of PPMC material systems. The research team focused on non-destructive inspection, multi-scale performance analysis, and molding flow simulation utilizing a complementary set of commercial and research tools that aid in design and understanding of PPMC materials and structures. The lessons learned from each approach about required degree of orientation information, variability in fiber orientation state, variability in performance, and best practices for modeling PPMC systems should be utilized wherever possible and added to as inspection and simulation technologies improve.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"46 2 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":"130768822","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":"A Visco-hyperelastic Constitutive Model for Fiber-Reinforced Rubber Composites","authors":"Rui Li, Dianyun Zhang","doi":"10.12783/ASC33/26145","DOIUrl":"https://doi.org/10.12783/ASC33/26145","url":null,"abstract":"","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"38 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":"132134032","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}
C. Yen, R. Kaste, Charles Chih-Tsai Chen, N. Carey
The design of new generation aircraft is driven by the vastly increased fuel cost and the resultant imperative for greater fuel efficiency. Carbon fiber composites have been used in aircraft structures to lower weight due to their superior stiffness and strength-to-weight properties. However, carbon composite material behavior under dynamic ballistic and blast loading conditions is relatively unknown. For aviation safety consideration, a computational constitutive model has been used to characterize the progressive failure behavior of carbon laminated composite plates subjected to ballistic and blast loading conditions. Using a meso-mechanics approach, a laminated composite is represented by a selected number of representative unidirectional layers with proper layup configurations. The damage progression in a unidirectional layer is assumed to be governed by a set of strain-rate dependent layer progressive failure criteria using the continuum damage mechanics approach. The composite failure model has been successfully implemented within LS-DYNA as a user-defined material subroutine. In this study, a series of experimental, close-in shock-hole blast tests on carbon composite panels, were simulated using the LS-DYNA-ALE method integrated with the ARL progressive failure composite model, which include strain rate effects on damage and fracture. The computational constitutive model has been validated to characterize the progressive failure behavior in carbon laminates subjected to close-in blast loading conditions with reasonable accuracy. The availability of this modeling tool will greatly facilitate the development of carbon composite structures with enhanced ballistic and blast survivability1.
{"title":"Modeling and Simulation of Carbon Composite Blast Behavior","authors":"C. Yen, R. Kaste, Charles Chih-Tsai Chen, N. Carey","doi":"10.12783/asc33/26017","DOIUrl":"https://doi.org/10.12783/asc33/26017","url":null,"abstract":"The design of new generation aircraft is driven by the vastly increased fuel cost and the resultant imperative for greater fuel efficiency. Carbon fiber composites have been used in aircraft structures to lower weight due to their superior stiffness and strength-to-weight properties. However, carbon composite material behavior under dynamic ballistic and blast loading conditions is relatively unknown. For aviation safety consideration, a computational constitutive model has been used to characterize the progressive failure behavior of carbon laminated composite plates subjected to ballistic and blast loading conditions. Using a meso-mechanics approach, a laminated composite is represented by a selected number of representative unidirectional layers with proper layup configurations. The damage progression in a unidirectional layer is assumed to be governed by a set of strain-rate dependent layer progressive failure criteria using the continuum damage mechanics approach. The composite failure model has been successfully implemented within LS-DYNA as a user-defined material subroutine. In this study, a series of experimental, close-in shock-hole blast tests on carbon composite panels, were simulated using the LS-DYNA-ALE method integrated with the ARL progressive failure composite model, which include strain rate effects on damage and fracture. The computational constitutive model has been validated to characterize the progressive failure behavior in carbon laminates subjected to close-in blast loading conditions with reasonable accuracy. The availability of this modeling tool will greatly facilitate the development of carbon composite structures with enhanced ballistic and blast survivability1.","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":"130903329","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}
N. Zobeiry, Sharareh Bayat, E. M. A. Anas, P. Mousavi, P. Abolmaesumi, A. Poursartip
{"title":"Temporal Enhanced Ultrasound as a Novel NDT Technique for Characterization of Defects in Composites","authors":"N. Zobeiry, Sharareh Bayat, E. M. A. Anas, P. Mousavi, P. Abolmaesumi, A. Poursartip","doi":"10.12783/ASC33/26149","DOIUrl":"https://doi.org/10.12783/ASC33/26149","url":null,"abstract":"","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"7 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":"128793027","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. Stapleton, Mathew J. Schey, C. Przybyla, M. Uchic, Helga Krieger, L. Appel, S. Zabler
One of research thrusts to push the limits of advanced fiber reinforced composites is to determine the link between manufacturing, resulting microstructure, and final structural properties. By bridging the gap between these topics, not only can we better understand how and why composites structurally work as they do, but we can potentially tailor the manufacturing processes for a desired resultant set of properties. To better illuminate the effects of manufacturing on microstructure and microstructure on properties, computational models are often employed. Using these models, we can gain insight on relationships that may otherwise remain unexplored. This research thrust is often labelled as ICME, integrated computational materials engineering.
{"title":"Comparison of Fiber Microstructural Characteristics for Two Grades of Carbon Fiber Composites","authors":"S. Stapleton, Mathew J. Schey, C. Przybyla, M. Uchic, Helga Krieger, L. Appel, S. Zabler","doi":"10.12783/ASC33/26058","DOIUrl":"https://doi.org/10.12783/ASC33/26058","url":null,"abstract":"One of research thrusts to push the limits of advanced fiber reinforced composites is to determine the link between manufacturing, resulting microstructure, and final structural properties. By bridging the gap between these topics, not only can we better understand how and why composites structurally work as they do, but we can potentially tailor the manufacturing processes for a desired resultant set of properties. To better illuminate the effects of manufacturing on microstructure and microstructure on properties, computational models are often employed. Using these models, we can gain insight on relationships that may otherwise remain unexplored. This research thrust is often labelled as ICME, integrated computational materials engineering.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"5 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":"125326384","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":"A Blended Damage and Fracture Mechanics Model for Progressive Damage Analysis of Notched Composite Structures","authors":"A. V. Oostrum, Bjorn Van Dongen, D. Zarouchas","doi":"10.12783/ASC33/25931","DOIUrl":"https://doi.org/10.12783/ASC33/25931","url":null,"abstract":"","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"24 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":"121516620","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 standard finite element implementation of intrinsic cohesive zone models (CZMs) based on the penalty method exhibits a distinct lack of numerical stability and/or convergence for stiff cohesive laws. This lack of stability is typically observed in the form of spurious oscillations in the normal and tangential tractions recovered at the cohesive interface. In this paper, we will present a robust, stabilized finite element formulation for CZMs that remedies traction oscillations, thus ensuring stability and convergence for any value of initial cohesive stiffness. A key advantage of the proposed formulation is that it generalizes the Nitsche’s method for modeling cohesive fracture with a large initial cohesive stiffness, thus enabling the implementation of intrinsic and extrinsic CZMs in a unified and variationally consistent manner. We present several numerical examples to demonstrate the stability, convergence and accuracy of the proposed formulation in two-dimensions. First, we will verify the accuracy using simple patch tests considering uniaxial tension, compression and shear loadings. Second, we will demonstrate the lack of spurious traction oscillations at cohesive interfaces of rectangular beams loaded under shear and three-point bending. To demonstrate the stability issues related with the spurious traction oscillation, we consider both isotropic as well as anisotropic CZMs, wherein the normal and tangential cohesive stiffness values are different. Our numerical results for high stiffness cases clearly show that the proposed formulation yields a smooth oscillation-free traction profile and ensures stability, whereas the standard formulation suffers from instability and/or convergence issues.
{"title":"A Stabilized Finite Element Formulation Remedying Traction Oscillations in Cohesive Interface Elements","authors":"Gourab Ghosh, Chandrasekhar Annavarapu, R. Duddu","doi":"10.12783/ASC33/26086","DOIUrl":"https://doi.org/10.12783/ASC33/26086","url":null,"abstract":"The standard finite element implementation of intrinsic cohesive zone models (CZMs) based on the penalty method exhibits a distinct lack of numerical stability and/or convergence for stiff cohesive laws. This lack of stability is typically observed in the form of spurious oscillations in the normal and tangential tractions recovered at the cohesive interface. In this paper, we will present a robust, stabilized finite element formulation for CZMs that remedies traction oscillations, thus ensuring stability and convergence for any value of initial cohesive stiffness. A key advantage of the proposed formulation is that it generalizes the Nitsche’s method for modeling cohesive fracture with a large initial cohesive stiffness, thus enabling the implementation of intrinsic and extrinsic CZMs in a unified and variationally consistent manner. We present several numerical examples to demonstrate the stability, convergence and accuracy of the proposed formulation in two-dimensions. First, we will verify the accuracy using simple patch tests considering uniaxial tension, compression and shear loadings. Second, we will demonstrate the lack of spurious traction oscillations at cohesive interfaces of rectangular beams loaded under shear and three-point bending. To demonstrate the stability issues related with the spurious traction oscillation, we consider both isotropic as well as anisotropic CZMs, wherein the normal and tangential cohesive stiffness values are different. Our numerical results for high stiffness cases clearly show that the proposed formulation yields a smooth oscillation-free traction profile and ensures stability, whereas the standard formulation suffers from instability and/or convergence issues.","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":"116197981","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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