{"title":"Thermal Failure of Composites under Heat Flow","authors":"S. Nomura, B. Karimi","doi":"10.12783/asc33/26051","DOIUrl":"https://doi.org/10.12783/asc33/26051","url":null,"abstract":"","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"100 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":"132470054","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}
Compressive strength and failure are a common benchmark to qualify the performance of a composite material for many applications. Standard test procedures typically involve compressive test of unidirectional or quasi-isotropic composites from where the properties are back calculated for a single composite ply to obtain the compressive strength of a ply and the laminate. In many applications, the composite material is under multi-axial stress states. In this paper, the influence of through-the-thickness stress on the compressive behavior is studied, with specific intent of replicating loading conditions seen in a bolted joint. Plane strain model of a laminated composite with explicit modeling of fiber and matrix is used in a layered stack-up with different boundary conditions to study the changes in compressive strength as well as residual (post-peak) strength.
{"title":"Effects of Out of Plane Stress on Progressive Kinking in Internal Zero Plies","authors":"P. Davidson, A. Waas","doi":"10.12783/ASC33/25980","DOIUrl":"https://doi.org/10.12783/ASC33/25980","url":null,"abstract":"Compressive strength and failure are a common benchmark to qualify the performance of a composite material for many applications. Standard test procedures typically involve compressive test of unidirectional or quasi-isotropic composites from where the properties are back calculated for a single composite ply to obtain the compressive strength of a ply and the laminate. In many applications, the composite material is under multi-axial stress states. In this paper, the influence of through-the-thickness stress on the compressive behavior is studied, with specific intent of replicating loading conditions seen in a bolted joint. Plane strain model of a laminated composite with explicit modeling of fiber and matrix is used in a layered stack-up with different boundary conditions to study the changes in compressive strength as well as residual (post-peak) strength.","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":"132900500","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}
Most currently available material models for composites do not allow for permanent strain. For applications such as ballistic containment and energy absorption applications, this results in under predicting material performance. This study extends the Matzenmiller, Lubliner and Taylor (MLT) model, a continuum damage mechanics (CDM) based constitutive model for unidirectional composites, to 3D solid elements, and enhances it with permanent strain capability. The model was implemented into the commercially available finite element code LS-Dyna. The model was validated with 3-point bend experiment. It was then used to simulate ballistic impact tests of an aluminum projectile against a glass fiber composite plate. As shown in the results below, this provides significant improvement in prediction of material performance
目前大多数可用的复合材料模型都不考虑永久应变。对于诸如弹道遏制和能量吸收等应用，这将导致材料性能低于预测。本研究将基于连续损伤力学(CDM)的单向复合材料本构模型Matzenmiller, Lubliner and Taylor (MLT)模型扩展到三维实体单元，并增强了该模型的永久应变能力。该模型在市售有限元代码LS-Dyna中实现。通过三点弯曲实验对模型进行了验证。然后用它来模拟铝弹对玻璃纤维复合板的弹道冲击试验。如下图所示，这在预测材料性能方面提供了显著的改进
{"title":"3D Continuum Damage Mechanics Model with Permanent Strain","authors":"James D. Dorer, Xinran Xiao","doi":"10.12783/asc33/25981","DOIUrl":"https://doi.org/10.12783/asc33/25981","url":null,"abstract":"Most currently available material models for composites do not allow for permanent strain. For applications such as ballistic containment and energy absorption applications, this results in under predicting material performance. This study extends the Matzenmiller, Lubliner and Taylor (MLT) model, a continuum damage mechanics (CDM) based constitutive model for unidirectional composites, to 3D solid elements, and enhances it with permanent strain capability. The model was implemented into the commercially available finite element code LS-Dyna. The model was validated with 3-point bend experiment. It was then used to simulate ballistic impact tests of an aluminum projectile against a glass fiber composite plate. As shown in the results below, this provides significant improvement in prediction of material performance","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"233 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":"132042706","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}
V. Varshney, V. Unnikrishnana, Jonghoon Lee, S. Sihn, A. Roy
Creating any workable materials construct for any viable applications using carbon or any other nanotubes would invariable involve dispersion of the nanotube in either twodimensional spatial mesh or three-dimensional volumetric space. These dispersed nanotubes invariably are interconnected via overlap or junctions. It is known that the atomic configuration of these nanotube junctions critically influence the bulk properties (structural, thermal, electrical, dielectric). Thus, it is extremely important to pay a close attention to how optimally these junctions can be formed to attain the desirable properties. In all practical situations, experimentally synthesized junctions (either single CNT junctions or junctions in 2D and 3D CNT network structures) are expected to have random orientation of defect sites (non-hexagonal rings) around the junction. Such random nature of junctions’ topology and defect characteristics is expected to affect their strength and durability as well as have impact on associated mesoscopic and macroscopic properties. In this work, we present a generic framework on creating junctions between CNTs with arbitrary spatial (orientation and degree of overlap) and intrinsic (chirality) specifications, as well as to tune degree of topological defects around the junction via a variety of defect annihilation approaches. Our method makes use of the primal/dual meshing concept where the development and manipulation of the junction nodes occur using a triangular meshes (primal mesh), which is eventually converted to its dual (honeycomb mesh) to render a fully-covalently bonded CNT junction where each carbon atom has 3 bonded neighbors (mimicking sp¬2 hybridization). This design approach offers an opportunity to investigate the effect of topological arrangement of defects around the junction on mechanical, electrical and thermal properties. In addition, this junction design methodology is applied to a CNT-graphene junction and to study the effect of local carbon defects (pentagonal or heptagonal carbon ring versus the hexagonal) on junction strength. It is observed that a symmetrical distribution of carbon ring defects around the CNT-graphene junction yield higher strength that that of irregular defect distribution.
{"title":"Atomistic Design of Carbon Nanotube Junctions of Arbitrary Junction Geometry","authors":"V. Varshney, V. Unnikrishnana, Jonghoon Lee, S. Sihn, A. Roy","doi":"10.12783/asc33/25940","DOIUrl":"https://doi.org/10.12783/asc33/25940","url":null,"abstract":"Creating any workable materials construct for any viable applications using carbon or any other nanotubes would invariable involve dispersion of the nanotube in either twodimensional spatial mesh or three-dimensional volumetric space. These dispersed nanotubes invariably are interconnected via overlap or junctions. It is known that the atomic configuration of these nanotube junctions critically influence the bulk properties (structural, thermal, electrical, dielectric). Thus, it is extremely important to pay a close attention to how optimally these junctions can be formed to attain the desirable properties. In all practical situations, experimentally synthesized junctions (either single CNT junctions or junctions in 2D and 3D CNT network structures) are expected to have random orientation of defect sites (non-hexagonal rings) around the junction. Such random nature of junctions’ topology and defect characteristics is expected to affect their strength and durability as well as have impact on associated mesoscopic and macroscopic properties. In this work, we present a generic framework on creating junctions between CNTs with arbitrary spatial (orientation and degree of overlap) and intrinsic (chirality) specifications, as well as to tune degree of topological defects around the junction via a variety of defect annihilation approaches. Our method makes use of the primal/dual meshing concept where the development and manipulation of the junction nodes occur using a triangular meshes (primal mesh), which is eventually converted to its dual (honeycomb mesh) to render a fully-covalently bonded CNT junction where each carbon atom has 3 bonded neighbors (mimicking sp¬2 hybridization). This design approach offers an opportunity to investigate the effect of topological arrangement of defects around the junction on mechanical, electrical and thermal properties. In addition, this junction design methodology is applied to a CNT-graphene junction and to study the effect of local carbon defects (pentagonal or heptagonal carbon ring versus the hexagonal) on junction strength. It is observed that a symmetrical distribution of carbon ring defects around the CNT-graphene junction yield higher strength that that of irregular defect distribution.","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":"133415283","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}
Achieving reliable means for failure prediction in composites is a standing challenge. To this end, an integrated approach for the diagnosis and prognosis of composites is underscored. It encompasses three key elements. The first is nondestructive inspection enabling 3D measurement of defect size, location and geometry coupled with an automated transition capability to finite element models. The second is accurate and cost effective 3D material property measurements with a minimum number of tests and methods. Finally, achieving structural strength and fatigue life prognosis results from combining the prior elements into comprehensive methods that would ultimately allow for capturing the failure mechanisms associated with multiple damage modes and their interaction. Future research directions emphasize the development of composites processing simulation tools to accelerate the attainment of quality standards and associated dependable allowables.
{"title":"Progress in Failure: Toward Reliable Failure Predictions in Composites","authors":"E. Armanios, G. Seon, Y. Nikishkov, A. Makeev","doi":"10.12783/ASC33/26096","DOIUrl":"https://doi.org/10.12783/ASC33/26096","url":null,"abstract":"Achieving reliable means for failure prediction in composites is a standing challenge. To this end, an integrated approach for the diagnosis and prognosis of composites is underscored. It encompasses three key elements. The first is nondestructive inspection enabling 3D measurement of defect size, location and geometry coupled with an automated transition capability to finite element models. The second is accurate and cost effective 3D material property measurements with a minimum number of tests and methods. Finally, achieving structural strength and fatigue life prognosis results from combining the prior elements into comprehensive methods that would ultimately allow for capturing the failure mechanisms associated with multiple damage modes and their interaction. Future research directions emphasize the development of composites processing simulation tools to accelerate the attainment of quality standards and associated dependable allowables.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"34 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":"132196583","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}
K. Oka, M. Kashiwagi, K. Miura, Yukihiro Sato, T. Abe, K. Takagi
{"title":"Effect of Stacking Sequence on Compressive Strength Reduction of Aircraft Composite Structures","authors":"K. Oka, M. Kashiwagi, K. Miura, Yukihiro Sato, T. Abe, K. Takagi","doi":"10.12783/asc33/26042","DOIUrl":"https://doi.org/10.12783/asc33/26042","url":null,"abstract":"","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"31 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":"122354516","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}
Polymer Matrix Composites (PMC) use is increasing in several industries due to their attractiveness relative to weight savings. Fabrication of this material system type requires a cure cycle, performed at elevated temperatures, that induces residual stresses at post-cure due to significant mismatch of fiber and matrix material properties. An integrated has been developed encompassing heat transfer analysis, a viscoelastic constitutive law, and cure kinetics to predict the residual stress distribution and corresponding geometric change after demolding. This paper summarizes efforts performed toward enhanced understanding of these residual thermal stress effects on the delamination type of failure for an angled composite flange under 4-point bending. This study paves the way for fully coupling the composite manufacturing process with structural performance through an Integrated Computational Materials Engineering (ICME) framework.
{"title":"Effects of Manufacturing-induced Residual Stress on the Strength of an L-Shaped Textile Composite Flange","authors":"James T. Roach, Weijia Chen, Dianyun Zhang","doi":"10.12783/asc33/25913","DOIUrl":"https://doi.org/10.12783/asc33/25913","url":null,"abstract":"Polymer Matrix Composites (PMC) use is increasing in several industries due to their attractiveness relative to weight savings. Fabrication of this material system type requires a cure cycle, performed at elevated temperatures, that induces residual stresses at post-cure due to significant mismatch of fiber and matrix material properties. An integrated has been developed encompassing heat transfer analysis, a viscoelastic constitutive law, and cure kinetics to predict the residual stress distribution and corresponding geometric change after demolding. This paper summarizes efforts performed toward enhanced understanding of these residual thermal stress effects on the delamination type of failure for an angled composite flange under 4-point bending. This study paves the way for fully coupling the composite manufacturing process with structural performance through an Integrated Computational Materials Engineering (ICME) framework.","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":"122421041","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}
Sergii G. Kravchenko, B. Denos, D. Sommer, Anthony Favoloro, W. Avery, Byron Pipes
The variability of open-hole tensile strength of a prepreg platelet molded composite with stochastic meso-morphology and deterministic platelet size was simulated by progressive failure analysis. Continuum damage mechanics was used to model the constitutive response of the platelet material. The analysis showed that openhole coupon fracture may occur at or away from the hole, depending on the stochastic meso-morphology details. It was also demonstrated that as the notch diameter is increased, the probability of fracture at the notch is increased.
{"title":"Analysis of Open Hole Tensile Strength in a Prepreg Platelet Molded Composite with Stochastic Meso-Structure","authors":"Sergii G. Kravchenko, B. Denos, D. Sommer, Anthony Favoloro, W. Avery, Byron Pipes","doi":"10.12783/ASC33/26057","DOIUrl":"https://doi.org/10.12783/ASC33/26057","url":null,"abstract":"The variability of open-hole tensile strength of a prepreg platelet molded composite with stochastic meso-morphology and deterministic platelet size was simulated by progressive failure analysis. Continuum damage mechanics was used to model the constitutive response of the platelet material. The analysis showed that openhole coupon fracture may occur at or away from the hole, depending on the stochastic meso-morphology details. It was also demonstrated that as the notch diameter is increased, the probability of fracture at the notch is increased.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"77 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":"122535218","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}
Carbon Fiber Reinforced Polymer (CFRP) composites are known to have highly variable modulus and strength based on fiber direction. This presents significant challenges when attempting to identify their mechanical properties. In particular, the composite strength and failure envelope in multi-axial loading is expected to have a complex nature due to anisotropy. Furthermore the heterogeneity of CFRP composites makes it even more difficult to model their failure modes and behavior. These intricacies become more pronounced at higher strain rates. In this study specimens with varying layup, geometry, and fiber volume fractions were tested in different loading conditions. Fiber volume fractions of the samples have been determined using thermogravimetric analysis (TGA) in nitrogen gas environment burnout tests. High strain rate response of CFRP composites are of scientific and technological interest. They are used extensively in aerospace (due to their high specific strength and stiffness) which necessitates their characterization for high velocity impact. The polymeric resins are of course expected to demonstrate rate dependence. Therefore split Hopkinson pressure bar (SHPB) experiments were used to determine the high strain rate response of CFRP composites in this study. The dependence of failure stress and strain on the strain rate was examined and summarized based on different loading conditions, geometries and layups. The failure stress is not very sensitive to strain rate in the range of this study, however comparisons with quasi-static data is done to further analyze this effect. The failure strains are higher when bidirectional specimens are loaded in the transverse direction (normal to the plane of fibers) compared to the axial loading of the unidirectional specimens. Meanwhile it was observed that the failure stresses of both unidirectional and bi-directional fiber specimens are close to each other. This has led to proposing a resin strength dominated failure mode for CFRP composites.
{"title":"Dynamic Behavior of Carbon Fiber Reinforced Polymer (CFRP) Composites at Higher Strain Rates","authors":"M. Hashim, D. Roux, A. Amirkhizi","doi":"10.12783/ASC33/25973","DOIUrl":"https://doi.org/10.12783/ASC33/25973","url":null,"abstract":"Carbon Fiber Reinforced Polymer (CFRP) composites are known to have highly variable modulus and strength based on fiber direction. This presents significant challenges when attempting to identify their mechanical properties. In particular, the composite strength and failure envelope in multi-axial loading is expected to have a complex nature due to anisotropy. Furthermore the heterogeneity of CFRP composites makes it even more difficult to model their failure modes and behavior. These intricacies become more pronounced at higher strain rates. In this study specimens with varying layup, geometry, and fiber volume fractions were tested in different loading conditions. Fiber volume fractions of the samples have been determined using thermogravimetric analysis (TGA) in nitrogen gas environment burnout tests. High strain rate response of CFRP composites are of scientific and technological interest. They are used extensively in aerospace (due to their high specific strength and stiffness) which necessitates their characterization for high velocity impact. The polymeric resins are of course expected to demonstrate rate dependence. Therefore split Hopkinson pressure bar (SHPB) experiments were used to determine the high strain rate response of CFRP composites in this study. The dependence of failure stress and strain on the strain rate was examined and summarized based on different loading conditions, geometries and layups. The failure stress is not very sensitive to strain rate in the range of this study, however comparisons with quasi-static data is done to further analyze this effect. The failure strains are higher when bidirectional specimens are loaded in the transverse direction (normal to the plane of fibers) compared to the axial loading of the unidirectional specimens. Meanwhile it was observed that the failure stresses of both unidirectional and bi-directional fiber specimens are close to each other. This has led to proposing a resin strength dominated failure mode for CFRP composites.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"447 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":"123045970","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}
4D printing is a manufacturing process which combines 3D printing with reconfiguration of the structure into a more complex form. The normal 4D printing would involve the deposition of polymeric materials with special properties to make flat layers. These flat layers are then subjected to some activation mechanism such as heat, light, water absorption etc. The materials in the flat layers then react to the activation mechanism to change the shape of the structure. 4D printing work was started in 2013 by Tibbits, and has received increasing attention. Most of the materials used in 4D printing have low mechanical properties. The modulus of these materials in only about 5 MPa, and these need to have special properties which can be expensive, and may not be widely available. 4D printing of composites is similar to the 4D printing mentioned above, except that the materials are regular composite materials that have been used to make structures such as airframes. These materials are light and stiff (modulus along fiber direction in order of 180 GPa), and strong (strength along fiber direction in the order of 1500 MPa). Flat layers of the composite are laid using either Hand Lay Up (HLU) or Automated Fiber Placement (AFP). The layers have different orientations to make unsymmetric laminates. Upon curing, the interaction of layer of different orientations will make the structure to be curved. This technique can be used to make structures of different curvatures, without the need to use complex molds. While the shape can be obtained, the question that remains is whether the structure is strong and stiff enough for engineering applications. This paper presents the formulation to determine the curvature, and the stiffness of the composite curved beams, intended for spring applications, that are made using 4D printing method.
{"title":"Development of Composite Leaf Springs Made by 4D Printing","authors":"S. Hoa","doi":"10.12783/ASC33/25975","DOIUrl":"https://doi.org/10.12783/ASC33/25975","url":null,"abstract":"4D printing is a manufacturing process which combines 3D printing with reconfiguration of the structure into a more complex form. The normal 4D printing would involve the deposition of polymeric materials with special properties to make flat layers. These flat layers are then subjected to some activation mechanism such as heat, light, water absorption etc. The materials in the flat layers then react to the activation mechanism to change the shape of the structure. 4D printing work was started in 2013 by Tibbits, and has received increasing attention. Most of the materials used in 4D printing have low mechanical properties. The modulus of these materials in only about 5 MPa, and these need to have special properties which can be expensive, and may not be widely available. 4D printing of composites is similar to the 4D printing mentioned above, except that the materials are regular composite materials that have been used to make structures such as airframes. These materials are light and stiff (modulus along fiber direction in order of 180 GPa), and strong (strength along fiber direction in the order of 1500 MPa). Flat layers of the composite are laid using either Hand Lay Up (HLU) or Automated Fiber Placement (AFP). The layers have different orientations to make unsymmetric laminates. Upon curing, the interaction of layer of different orientations will make the structure to be curved. This technique can be used to make structures of different curvatures, without the need to use complex molds. While the shape can be obtained, the question that remains is whether the structure is strong and stiff enough for engineering applications. This paper presents the formulation to determine the curvature, and the stiffness of the composite curved beams, intended for spring applications, that are made using 4D printing method.","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":"115271477","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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