Advanced composite materials play vital structural roles in automotive, aerospace and marine industries. Recently, reduction in arctic sea ice region over the last three decades has opened new sailing routes which are more efficient and economical. This has resulted in the increased use of marine and naval vessels in extreme low temperature arctic conditions. The fundamental challenge of operating in such cold and harsh environment lies in the understanding of how materials and structures behave and perform in extreme low temperature. Composite sandwich structures far exceeds classical composite laminates in terms of flexural capability and performance. In this study, we experimentally investigate the impact and post-impact bending response of Divinycell H-100 foam core sandwich panel with woven carbon fiber reinforced polymer (CFRP) facesheets. Specimens were conditioned and impacted over a temperature range (from room temperature down to -70°C). Results show that exposure to low temperature generally causes more severe damage in the specimens. Post-mortem inspection using x-ray micro-computed tomography revealed complex failure mechanisms in the composite facesheets (such as matrix crack, delamination and fiber breakage) and foam core (core crushing, core shearing and interfacial debonding).
{"title":"Impact Performance and Flexural Behavior of Composite Sandwich Structures in Low Temperature Arctic Conditions","authors":"K. Tan, M. H. Khan","doi":"10.12783/ASC33/25971","DOIUrl":"https://doi.org/10.12783/ASC33/25971","url":null,"abstract":"Advanced composite materials play vital structural roles in automotive, aerospace and marine industries. Recently, reduction in arctic sea ice region over the last three decades has opened new sailing routes which are more efficient and economical. This has resulted in the increased use of marine and naval vessels in extreme low temperature arctic conditions. The fundamental challenge of operating in such cold and harsh environment lies in the understanding of how materials and structures behave and perform in extreme low temperature. Composite sandwich structures far exceeds classical composite laminates in terms of flexural capability and performance. In this study, we experimentally investigate the impact and post-impact bending response of Divinycell H-100 foam core sandwich panel with woven carbon fiber reinforced polymer (CFRP) facesheets. Specimens were conditioned and impacted over a temperature range (from room temperature down to -70°C). Results show that exposure to low temperature generally causes more severe damage in the specimens. Post-mortem inspection using x-ray micro-computed tomography revealed complex failure mechanisms in the composite facesheets (such as matrix crack, delamination and fiber breakage) and foam core (core crushing, core shearing and interfacial debonding).","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"15 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":"115506001","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}
F. Bobaru, J. Mehrmashhadi, Ziguang Chen, S. Niazi
In fiber reinforced composites (FRCs), microcracks often initiate at the interface between fibers and the matrix, or from pores in the matrix. With an explicit microstructure representation, a peridynamic model can simulate the initiation, growth, and coalescence of intraply microcracks into macrocracks in the transverse loading of a FRC. The size of the simulated sample, in this case, is limited by the computational cost. For lamina-level simulations, we employ a homogenization strategy for the transversely loaded FRC with a peridynamic model, the Intermediately Homogenized Peridynamic (IH-PD) model for two-phase composites. We compare our results with three-point bending experiments from the literature. The results show that the IH-PD model mimics the tortuous crack path observed experimentally, without having to rely on the detailed microstructure. Moreover, the IH-PD results for the load versus crack opening displacement match very well the experimentally measured data.
{"title":"Intraply Fracture in Fiber-Reinforced Composites: A Peridynamic Analysis","authors":"F. Bobaru, J. Mehrmashhadi, Ziguang Chen, S. Niazi","doi":"10.12783/ASC33/26039","DOIUrl":"https://doi.org/10.12783/ASC33/26039","url":null,"abstract":"In fiber reinforced composites (FRCs), microcracks often initiate at the interface between fibers and the matrix, or from pores in the matrix. With an explicit microstructure representation, a peridynamic model can simulate the initiation, growth, and coalescence of intraply microcracks into macrocracks in the transverse loading of a FRC. The size of the simulated sample, in this case, is limited by the computational cost. For lamina-level simulations, we employ a homogenization strategy for the transversely loaded FRC with a peridynamic model, the Intermediately Homogenized Peridynamic (IH-PD) model for two-phase composites. We compare our results with three-point bending experiments from the literature. The results show that the IH-PD model mimics the tortuous crack path observed experimentally, without having to rely on the detailed microstructure. Moreover, the IH-PD results for the load versus crack opening displacement match very well the experimentally measured data.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"42 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":"127458354","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 paper, we investigate Mode-I and Mode-II delamination behavior of Discontinuous Fiber Composites (DFCs). Owing to the complex heterogeneous mesostructure in DFCs, conventional testing methodologies such as the double cantilever beam (DCB) and end-notched flexure (ENF) tests used to characterize Mode-I and Mode-II interlaminar failure may fail to characterize the non-linear behavior during delamination. This is because DCB and ENF tests based on Linear Elastic Fracture Mechanics (LEFM) models, fails to account for the quasi-brittleness of DFCs. As a result, this approach may not be able to capture the variation in the Fracture Process Zone (FPZ) which becomes large due the distributed damage in the platelets. Hence, there is a need to account for this non-linear behavior of the FPZ to effectively estimate the delamination fracture energy. This paper proposes an experimental investigation on the effects of the FPZ on the inter-laminar delamination of DFCs. To shed light on the role of the FPZ size versus the structure size and geometry, geometrically-scaled DCB and ENF specimens were tested. The results show a significant size effect. While for small sizes the specimens exhibit a limited strength reduction by the presence of the crack (which indicates a pseudo-ductile behaviour), the failure becomes more and more brittle for larger sizes. Future work will focus on the understanding of this phenomenon leveraging stochastic Finite Element modelling and quasi-brittle fracture mechanics.
{"title":"Delamination Resistance and Size Effect in Discontinuous Fiber Composites","authors":"Rohith Jayaram, S. Ko, Jinkyu Yang, M. Salviato","doi":"10.12783/ASC33/26000","DOIUrl":"https://doi.org/10.12783/ASC33/26000","url":null,"abstract":"In this paper, we investigate Mode-I and Mode-II delamination behavior of Discontinuous Fiber Composites (DFCs). Owing to the complex heterogeneous mesostructure in DFCs, conventional testing methodologies such as the double cantilever beam (DCB) and end-notched flexure (ENF) tests used to characterize Mode-I and Mode-II interlaminar failure may fail to characterize the non-linear behavior during delamination. This is because DCB and ENF tests based on Linear Elastic Fracture Mechanics (LEFM) models, fails to account for the quasi-brittleness of DFCs. As a result, this approach may not be able to capture the variation in the Fracture Process Zone (FPZ) which becomes large due the distributed damage in the platelets. Hence, there is a need to account for this non-linear behavior of the FPZ to effectively estimate the delamination fracture energy. This paper proposes an experimental investigation on the effects of the FPZ on the inter-laminar delamination of DFCs. To shed light on the role of the FPZ size versus the structure size and geometry, geometrically-scaled DCB and ENF specimens were tested. The results show a significant size effect. While for small sizes the specimens exhibit a limited strength reduction by the presence of the crack (which indicates a pseudo-ductile behaviour), the failure becomes more and more brittle for larger sizes. Future work will focus on the understanding of this phenomenon leveraging stochastic Finite Element modelling and quasi-brittle fracture mechanics.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"83 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":"124850008","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 research, a multiscale modeling framework is developed and applied to the analysis of adhesively bonded composite joints under mechanical loading. The primary goal is to obtain an improved understanding of damage initiation and failure at the relevant length scales and predicting the consequent effects at the structural scale. The methodology utilizes damage information at the atomic level, addressed using molecular dynamics (MD), and couples it with a method of cells based micromechanics model for the nonlinear and damage analysis of carbon fiber reinforced polymer (CFRP) composite. This damage analysis technique is then used to predict the multiscale nonlinear effects in hot-spot zones, such as the adhesive/adherend interface, in adhesively bonded T-joints which will assist in the development of methods for prevention or delay of the most common forms of failure in such built-up components.
{"title":"Multiscale Modeling of Bonded T-Joints Using Atomistically Informed Method of Cells","authors":"Ashwin Rai, A. Chattopadhyay","doi":"10.12783/ASC33/26085","DOIUrl":"https://doi.org/10.12783/ASC33/26085","url":null,"abstract":"In this research, a multiscale modeling framework is developed and applied to the analysis of adhesively bonded composite joints under mechanical loading. The primary goal is to obtain an improved understanding of damage initiation and failure at the relevant length scales and predicting the consequent effects at the structural scale. The methodology utilizes damage information at the atomic level, addressed using molecular dynamics (MD), and couples it with a method of cells based micromechanics model for the nonlinear and damage analysis of carbon fiber reinforced polymer (CFRP) composite. This damage analysis technique is then used to predict the multiscale nonlinear effects in hot-spot zones, such as the adhesive/adherend interface, in adhesively bonded T-joints which will assist in the development of methods for prevention or delay of the most common forms of failure in such built-up components.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"27 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":"124906798","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}
It has been recently observed that addition and dispersion of a few weight percent of nanoscale particles in polymer matrix composites have reduced brittleness and microcracking of polymer matrices and improve their strain to failure and fracture toughness without incurring weight penalty. This paper aims at using molecular dynamics to study length scale effects at the nanoscale, identifying the existence of a lower bound on flaw-size that marks the transition from brittle to ductile failure in nanocomposites, thereby causing deviations from linear elastic fracture mechanics (LEFM) predictions. Crack-tip bond-order based prediction of critical far-field stress and stress intensity factor is also addressed in this work. The MD predictions are observed to deviate from LEFM predictions below a certain length-scale. This study on nanoscale fracture of crystalline (graphene) lays the foundations for the future atomistic predictions of fracture in amorphous (polymer) nanocomposite systems.
{"title":"Length-Scale Effect on Fracture Behavior Of Nano-Composites","authors":"Samit Roy, Anubhav Roy","doi":"10.12783/ASC33/25943","DOIUrl":"https://doi.org/10.12783/ASC33/25943","url":null,"abstract":"It has been recently observed that addition and dispersion of a few weight percent of nanoscale particles in polymer matrix composites have reduced brittleness and microcracking of polymer matrices and improve their strain to failure and fracture toughness without incurring weight penalty. This paper aims at using molecular dynamics to study length scale effects at the nanoscale, identifying the existence of a lower bound on flaw-size that marks the transition from brittle to ductile failure in nanocomposites, thereby causing deviations from linear elastic fracture mechanics (LEFM) predictions. Crack-tip bond-order based prediction of critical far-field stress and stress intensity factor is also addressed in this work. The MD predictions are observed to deviate from LEFM predictions below a certain length-scale. This study on nanoscale fracture of crystalline (graphene) lays the foundations for the future atomistic predictions of fracture in amorphous (polymer) nanocomposite systems.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"18 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":"125078285","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}
Andre Lee, David F. Vogelsang, Jonathan E. Dannatt, R. Maleczka
Thermosetting polyimides terminated with phenylethynly phthalic imides are the current state-of-the-art high temperature resin for use in structural composite applications. However, due to the presence of imide group these resins often suffer high moisture uptake leading to property degradation during use. In addition, the need to remove condensation near the crosslinking reaction temperature as well as high glass transition temperature of unreacted oligomers, the processing window for this class of thermosetting is very narrow. Hence, the need to develop compounds with the same terminating group with ease of processing is of significant interest. In this work, double-decker shaped silsesquioxane (DDSQ) terminated with multiple phenylethynyl groups was developed and curing process investigated. It was anticipated that DDSQ as the backbone can provide the needed monodispersed characteristics in its molecular weight, while phenylethynyl groups form different isomers (region- and stereo-) about the SiO core of DDSQ. This approach provides ease of processing while eliminate crystallinity. In addition, the inorganic nature of these compounds also exhibited a significant reduction in the moisture uptake which can greatly enhance in-service performance of composites. Synthesis and purification of needed chlorosilanes and the subsequence separation of these functionalized DDSQs by liquid chromatography were performed without the need to use fractional crystallization as the first preparation step are presented. This approach greatly reduces the complexity and enables continuous process.
{"title":"Hybrid Structured Phenylethynyl Silsesquioxane Resin Composites","authors":"Andre Lee, David F. Vogelsang, Jonathan E. Dannatt, R. Maleczka","doi":"10.12783/ASC33/26107","DOIUrl":"https://doi.org/10.12783/ASC33/26107","url":null,"abstract":"Thermosetting polyimides terminated with phenylethynly phthalic imides are the current state-of-the-art high temperature resin for use in structural composite applications. However, due to the presence of imide group these resins often suffer high moisture uptake leading to property degradation during use. In addition, the need to remove condensation near the crosslinking reaction temperature as well as high glass transition temperature of unreacted oligomers, the processing window for this class of thermosetting is very narrow. Hence, the need to develop compounds with the same terminating group with ease of processing is of significant interest. In this work, double-decker shaped silsesquioxane (DDSQ) terminated with multiple phenylethynyl groups was developed and curing process investigated. It was anticipated that DDSQ as the backbone can provide the needed monodispersed characteristics in its molecular weight, while phenylethynyl groups form different isomers (region- and stereo-) about the SiO core of DDSQ. This approach provides ease of processing while eliminate crystallinity. In addition, the inorganic nature of these compounds also exhibited a significant reduction in the moisture uptake which can greatly enhance in-service performance of composites. Synthesis and purification of needed chlorosilanes and the subsequence separation of these functionalized DDSQs by liquid chromatography were performed without the need to use fractional crystallization as the first preparation step are presented. This approach greatly reduces the complexity and enables continuous process.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"20 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":"123766612","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}
M. Flores, Nathan Sesar, B. Wheeler, Andrew Sharits, D. Mollenhauer
Strengthening the fundamental understanding of micromechanical methods in continuity is a critical aspect in developing and designing future composite systems. Virtual testing has provided additional understanding of the behavior of materials on a microstructural scale. However, experiments must be executed to determine their validity. Modeling realistic microstructures under realistic loading conditions could help develop physically based micromechanical constitutive laws needed to predict the intrinsic failure. In this study, discrete damage modeling was performed on a microstructure of polymer matrix composite under transverse compressive loading. The discrete damage model utilized a Regularized eXtended Finite Element Methodology (RXFEM formulation to initiate cracks, a Cohesive Zone Methodology (CZM) was used to simulate crack propagation, as well as debonding between the fibers and matrix. The discrete damage model provides insight to the microstructural behavior under transverse loading and correlates well with experiment.
{"title":"Discrete Damage Modeling for a Transverse Compression Experiment of a Polymer Matrix Composite","authors":"M. Flores, Nathan Sesar, B. Wheeler, Andrew Sharits, D. Mollenhauer","doi":"10.12783/ASC33/26006","DOIUrl":"https://doi.org/10.12783/ASC33/26006","url":null,"abstract":"Strengthening the fundamental understanding of micromechanical methods in continuity is a critical aspect in developing and designing future composite systems. Virtual testing has provided additional understanding of the behavior of materials on a microstructural scale. However, experiments must be executed to determine their validity. Modeling realistic microstructures under realistic loading conditions could help develop physically based micromechanical constitutive laws needed to predict the intrinsic failure. In this study, discrete damage modeling was performed on a microstructure of polymer matrix composite under transverse compressive loading. The discrete damage model utilized a Regularized eXtended Finite Element Methodology (RXFEM formulation to initiate cracks, a Cohesive Zone Methodology (CZM) was used to simulate crack propagation, as well as debonding between the fibers and matrix. The discrete damage model provides insight to the microstructural behavior under transverse loading and correlates well with experiment.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"89 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":"125461804","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}
Juan Su, S. Stapleton, S. Johnson, S. Nolet, N. Althoff, J. Sherwood
{"title":"Effects of Localized Manufacturing-Induced Defects in Wind Turbine Blades","authors":"Juan Su, S. Stapleton, S. Johnson, S. Nolet, N. Althoff, J. Sherwood","doi":"10.12783/asc33/26068","DOIUrl":"https://doi.org/10.12783/asc33/26068","url":null,"abstract":"","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":"114543778","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}
Jing Li, Sakamoto Jumpei, Hiroki Wizumi, Yue Huang, N. Kishimoto, Y. Oya, T. Okabe
An Atomic-level model that can analyze the influence of the synthesis conditions (Molar ration, catalyst et al.) on the mechanical properties of phenol formaldehyde (PF) resins has been developed. This model clarified the relationship between synthesis conditions, the structure formation, and the structure-depended mechanical properties by introducing a comprehensive reaction model that includes both addition and condensation reactions. We validated the effectiveness of the model by verifying the influence of primary synthetic index, molar ratio, on the mechanical properties such as glass transition temperature (Tg) of resol resins. The computing cost has also been reduced since we adopted a multi-scale model which combined the Quantum chemistry calculation (QM), Monte Carlo (MC), and Molecular Dynamics (MD) method. This model will be helpful to reduce the cost of attempts at synthetic PF resins and more efficiently to find the suitable synthesis conditions for the desired material properties.
{"title":"From Addition Reactions to Cross-Linked Network Formation","authors":"Jing Li, Sakamoto Jumpei, Hiroki Wizumi, Yue Huang, N. Kishimoto, Y. Oya, T. Okabe","doi":"10.12783/ASC33/25964","DOIUrl":"https://doi.org/10.12783/ASC33/25964","url":null,"abstract":"An Atomic-level model that can analyze the influence of the synthesis conditions (Molar ration, catalyst et al.) on the mechanical properties of phenol formaldehyde (PF) resins has been developed. This model clarified the relationship between synthesis conditions, the structure formation, and the structure-depended mechanical properties by introducing a comprehensive reaction model that includes both addition and condensation reactions. We validated the effectiveness of the model by verifying the influence of primary synthetic index, molar ratio, on the mechanical properties such as glass transition temperature (Tg) of resol resins. The computing cost has also been reduced since we adopted a multi-scale model which combined the Quantum chemistry calculation (QM), Monte Carlo (MC), and Molecular Dynamics (MD) method. This model will be helpful to reduce the cost of attempts at synthetic PF resins and more efficiently to find the suitable synthesis conditions for the desired material properties.","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":"129551364","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}
Sota Oshima, A. Yoshimura, Y. Hirano, T. Ogasawara
A simple and accurate data reduction scheme for wedge loaded DCB specimens used for mode I fracture toughness tests was introduced in this study. The effects of axial loading applied to the specimen by wedges were considered in the data reduction scheme. The presented method was verified by CFRP interlaminar fracture toughness tests. A relationship between strain on the surface of a specimen and opening load (strain rate) was experimentally and theoretically obtained to compare the deformation of the specimens during the wedge loaded DCB tests. Strain rate obtained by experiments well fitted the theoretical values. R-curves obtained by the wedge loaded DCB tests were compared with standard DCB tests and other data reduction methods. mode I fracture toughness both at the onset of crack growth and during crack propagation obtained by the wedge loaded DCB and standard DCB tests corresponded reasonably by using the presented data reduction method. Fracture toughness obtained by the modified compliance calibration method (MCCM) and modified beam theory (MBT) were lower than that obtained by the presented method. In addition, in order to clarify the failure mechanisms of CFRP laminates and adhesively bonded CFRP joints, in-situ observation around the crack tip with an optical microscope during fracture toughness tests was carried out. Sequential photographs were taken during the fracture toughness tests. Normal strain in crack opening direction was analyzed by the digital image correlation (DIC) method.
{"title":"Characterization of Mode I Interlaminar Fracture Toughness in Composite Materials Using Wedge Loaded DCB Specimens","authors":"Sota Oshima, A. Yoshimura, Y. Hirano, T. Ogasawara","doi":"10.12783/asc33/25915","DOIUrl":"https://doi.org/10.12783/asc33/25915","url":null,"abstract":"A simple and accurate data reduction scheme for wedge loaded DCB specimens used for mode I fracture toughness tests was introduced in this study. The effects of axial loading applied to the specimen by wedges were considered in the data reduction scheme. The presented method was verified by CFRP interlaminar fracture toughness tests. A relationship between strain on the surface of a specimen and opening load (strain rate) was experimentally and theoretically obtained to compare the deformation of the specimens during the wedge loaded DCB tests. Strain rate obtained by experiments well fitted the theoretical values. R-curves obtained by the wedge loaded DCB tests were compared with standard DCB tests and other data reduction methods. mode I fracture toughness both at the onset of crack growth and during crack propagation obtained by the wedge loaded DCB and standard DCB tests corresponded reasonably by using the presented data reduction method. Fracture toughness obtained by the modified compliance calibration method (MCCM) and modified beam theory (MBT) were lower than that obtained by the presented method. In addition, in order to clarify the failure mechanisms of CFRP laminates and adhesively bonded CFRP joints, in-situ observation around the crack tip with an optical microscope during fracture toughness tests was carried out. Sequential photographs were taken during the fracture toughness tests. Normal strain in crack opening direction was analyzed by the digital image correlation (DIC) method.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"21 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":"128641095","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：