The ongoing demand to reduce the LCOE (Levelized Cost of Electricity) drives the wind industry to explore new technologies that will advance the state-of-the-art for composite wind blade manufacturing. These new technologies span the range from new resins and fibers, to improved blade designs, to innovative manufacturing techniques. However, since the introduction and widespread adoption of vacuumassisted resin-infusion techniques for blade making, there has been no significant change in the basic labor-intensive manufacturing process for wind blade production. In the current research, a Techno-Economic Model (TEM) and a complementary simulation of a generic wind blade manufacturing facility are developed. The TEM is sufficiently robust to take into account the very rapid product refresh cycle (and concurrent consumption of capital), differences in blade lengths, and the potential future composite technologies such as carbon fiber and thermoplastics that could impact the blade design and resulting manufacturing processes. To investigate the long-term costs and benefits, the TEM also takes into account the cash flows over a multi-year period so that the true value of improvements can be identified and used to justify capital investment in automation and other process changes. The complimentary simulation is built in DELMIA. DELMIA allows for a visual tool to evaluate how changes in the manufacturing steps will impact process flow and timing. The integration of these two models into a full Techno-Economic Analysis (TEA) provides a comprehensive tool to identify opportunities for increasing throughput and for exploring the impact of capital investments.
{"title":"Techno-Economic Model and Simulation for Wind Blade Manufacturing","authors":"S. Johnson, M. Polcari, J. Sherwood","doi":"10.12783/asc33/26009","DOIUrl":"https://doi.org/10.12783/asc33/26009","url":null,"abstract":"The ongoing demand to reduce the LCOE (Levelized Cost of Electricity) drives the wind industry to explore new technologies that will advance the state-of-the-art for composite wind blade manufacturing. These new technologies span the range from new resins and fibers, to improved blade designs, to innovative manufacturing techniques. However, since the introduction and widespread adoption of vacuumassisted resin-infusion techniques for blade making, there has been no significant change in the basic labor-intensive manufacturing process for wind blade production. In the current research, a Techno-Economic Model (TEM) and a complementary simulation of a generic wind blade manufacturing facility are developed. The TEM is sufficiently robust to take into account the very rapid product refresh cycle (and concurrent consumption of capital), differences in blade lengths, and the potential future composite technologies such as carbon fiber and thermoplastics that could impact the blade design and resulting manufacturing processes. To investigate the long-term costs and benefits, the TEM also takes into account the cash flows over a multi-year period so that the true value of improvements can be identified and used to justify capital investment in automation and other process changes. The complimentary simulation is built in DELMIA. DELMIA allows for a visual tool to evaluate how changes in the manufacturing steps will impact process flow and timing. The integration of these two models into a full Techno-Economic Analysis (TEA) provides a comprehensive tool to identify opportunities for increasing throughput and for exploring the impact of capital investments.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"26 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":"122716492","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}
Benchmark examples based on Single Leg Bending (SLB) specimens with equal and unequal bending arm thicknesses were used to assess the performance of delamination prediction capabilities in finite element codes. First, the development of the quasi-static benchmark cases using the Virtual Crack Closure Technique (VCCT) is discussed in detail. Second, based on the quasi-static benchmark results, additional benchmark cases to assess delamination propagation under fatigue loading are created. Third, the application is demonstrated for the commercial finite element code Abaqus Standard 2018. The benchmark cases are compared to results obtained from VCCTbased, automated quasi-static propagation analysis. A comparison with results from automated fatigue propagation analysis was not performed at this point since the current version of Abaqus does not include this capability under variable mixed-mode conditions. In general, good agreement between the results obtained from the quasistatic propagation analysis and the benchmark results were achieved. Overall, the benchmarking procedure proved valuable for analysis verification.
采用弯曲臂厚度相等和不等的单腿弯曲(SLB)试件的基准算例，对有限元程序中分层预测能力的性能进行了评估。首先，详细讨论了基于虚拟裂纹闭合技术(VCCT)的准静态基准案例的开发。其次，在准静态基准测试结果的基础上，建立了额外的基准测试案例来评估疲劳载荷下的分层扩展。第三，对商业有限元代码Abaqus Standard 2018进行了应用演示。将基准案例与基于vcct的自动化准静态传播分析结果进行比较。由于当前版本的Abaqus不包括可变混合模式条件下的这种能力，因此没有与自动疲劳传播分析的结果进行比较。总的来说，准静态传播分析的结果与基准测试的结果非常吻合。总的来说，对标程序证明对分析验证是有价值的。
{"title":"A Benchmark Example for Delamination Propagation Predictions Based on the Single Leg Bending Specimen Under Quasi-static and Fatigue Loading","authors":"R. Krueger, L. Deobald, H. Gu","doi":"10.12783/ASC33/26004","DOIUrl":"https://doi.org/10.12783/ASC33/26004","url":null,"abstract":"Benchmark examples based on Single Leg Bending (SLB) specimens with equal and unequal bending arm thicknesses were used to assess the performance of delamination prediction capabilities in finite element codes. First, the development of the quasi-static benchmark cases using the Virtual Crack Closure Technique (VCCT) is discussed in detail. Second, based on the quasi-static benchmark results, additional benchmark cases to assess delamination propagation under fatigue loading are created. Third, the application is demonstrated for the commercial finite element code Abaqus Standard 2018. The benchmark cases are compared to results obtained from VCCTbased, automated quasi-static propagation analysis. A comparison with results from automated fatigue propagation analysis was not performed at this point since the current version of Abaqus does not include this capability under variable mixed-mode conditions. In general, good agreement between the results obtained from the quasistatic propagation analysis and the benchmark results were achieved. Overall, the benchmarking procedure proved valuable for analysis verification.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"33 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":"126094358","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}
This work investigated the buckling stability of isogrid panels manufactured using fused deposition modelling (FDM). In particular, it verified the use of existing closed form analytical solutions and finite element analyses for predicting both global and local buckling loads and modes for these structures. FDM-produced isogrid samples were subjected to uniaxial quasi-static compression with boundary conditions approximating simple supports. Buckling values and mode shapes were obtained from Digital Image Correlation (DIC). The values obtained experimentally were compared to buckling loads calculated using finite element analysis and closed form solutions for orthotropic materials. Good agreement was obtained in comparing finite element analysis to experimental results for both global and local modes, while closed-form solutions compared well for the global modes for which the solutions were intended.
{"title":"Buckling Stability of Additively Manufactured Isogrid","authors":"S. Ananth, T. Whitney, E. Toubia","doi":"10.12783/ASC33/26164","DOIUrl":"https://doi.org/10.12783/ASC33/26164","url":null,"abstract":"This work investigated the buckling stability of isogrid panels manufactured using fused deposition modelling (FDM). In particular, it verified the use of existing closed form analytical solutions and finite element analyses for predicting both global and local buckling loads and modes for these structures. FDM-produced isogrid samples were subjected to uniaxial quasi-static compression with boundary conditions approximating simple supports. Buckling values and mode shapes were obtained from Digital Image Correlation (DIC). The values obtained experimentally were compared to buckling loads calculated using finite element analysis and closed form solutions for orthotropic materials. Good agreement was obtained in comparing finite element analysis to experimental results for both global and local modes, while closed-form solutions compared well for the global modes for which the solutions were intended.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"36 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":"123647828","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 novel test configuration has been developed to induce combined stress-states of inplane longitudinal tension and transverse compression in unidirectional (UD) composite layers. Two different multi-directional laminates have been designed incorporating UD carbon/epoxy plies embedded in angle-ply blocks of the same material. The scissoring deformation of the angle-plies induces compression in the central UD layers when the composite is strained in the 0° fibre direction. The amount of transverse compressive stress is determined through an inverse identification method from the measured surface strains of the laminates. Despite the large in-plane transverse compressive strain generated, there is only about 9% drop in the failure strain of the laminates when compared to the baseline failure strain of the UD carbon/epoxy material.
我们开发了一种新颖的测试配置，用于在单向（UD）复合材料层中诱导平面纵向拉伸和横向压缩的组合应力状态。我们设计了两种不同的多向层压板，将 UD 碳/环氧层嵌入相同材料的角层块中。当复合材料在 0° 纤维方向上受到应变时，角材的剪切变形会导致中心 UD 层受到压缩。横向压缩应力的大小是根据测量到的层压板表面应变，通过反识别方法确定的。尽管产生了较大的面内横向压缩应变，但与 UD 碳/环氧材料的基线破坏应变相比，层压板的破坏应变仅下降了约 9%。
{"title":"A Novel Test Method to Induce Bi-Axial Stress States in Thin-Ply Carbon Composites Under Combined Longitudinal Tension and Transverse Compression","authors":"Tamas Rev, G. Czél, M. Wisnom","doi":"10.12783/asc33/25937","DOIUrl":"https://doi.org/10.12783/asc33/25937","url":null,"abstract":"A novel test configuration has been developed to induce combined stress-states of inplane longitudinal tension and transverse compression in unidirectional (UD) composite layers. Two different multi-directional laminates have been designed incorporating UD carbon/epoxy plies embedded in angle-ply blocks of the same material. The scissoring deformation of the angle-plies induces compression in the central UD layers when the composite is strained in the 0° fibre direction. The amount of transverse compressive stress is determined through an inverse identification method from the measured surface strains of the laminates. Despite the large in-plane transverse compressive strain generated, there is only about 9% drop in the failure strain of the laminates when compared to the baseline failure strain of the UD carbon/epoxy material.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"44 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":"126992011","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}
Due to the high specific stiffness and strength, composite shells have been widely used in fuel tanks of launch vehicles. The buckling analysis of composite shells with cutouts based on the finite element (FE) method is too time-consuming. From the point-of-view of model size reduction, a novel Proper Orthogonal Decomposition (POD)-based buckling method is proposed in this paper, which can significantly increase the computational efficiency of buckling analysis. In order to improve the efficiency and effectiveness of prediction and optimization of composite shells with multiple cutouts, the POD method is integrated into an optimization framework that uses Gaussian process (GP) machine learning method. First, the training set used for the machine learning training is generated efficiently by means of the POD method. Then, the obtained set is trained and tested based on the Gaussian process method. The inputs are ply angles of the composite shell and the output is the buckling load of the composite shell containing cutouts. In order to maximize the buckling load of the composite shell against cutouts, the Genetic Algorithm is combined with the trained Gaussian process method to search for the optimal ply angles. Finally, an illustrative example is carried out to demonstrate the effectiveness of the proposed prediction and optimization framework.
{"title":"Optimal Design of Composite Shells with Multiple Cutouts Based on POD and Machine Learning Methods","authors":"K. Tian, Shiyao Lin, Jiaxin Zhang, A. Waas","doi":"10.12783/ASC33/26160","DOIUrl":"https://doi.org/10.12783/ASC33/26160","url":null,"abstract":"Due to the high specific stiffness and strength, composite shells have been widely used in fuel tanks of launch vehicles. The buckling analysis of composite shells with cutouts based on the finite element (FE) method is too time-consuming. From the point-of-view of model size reduction, a novel Proper Orthogonal Decomposition (POD)-based buckling method is proposed in this paper, which can significantly increase the computational efficiency of buckling analysis. In order to improve the efficiency and effectiveness of prediction and optimization of composite shells with multiple cutouts, the POD method is integrated into an optimization framework that uses Gaussian process (GP) machine learning method. First, the training set used for the machine learning training is generated efficiently by means of the POD method. Then, the obtained set is trained and tested based on the Gaussian process method. The inputs are ply angles of the composite shell and the output is the buckling load of the composite shell containing cutouts. In order to maximize the buckling load of the composite shell against cutouts, the Genetic Algorithm is combined with the trained Gaussian process method to search for the optimal ply angles. Finally, an illustrative example is carried out to demonstrate the effectiveness of the proposed prediction and optimization framework.","PeriodicalId":337735,"journal":{"name":"American Society for Composites 2018","volume":"74 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":"131260703","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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