The Experts below are selected from a list of 63 Experts worldwide ranked by ideXlab platform
Remko Akkerman - One of the best experts on this subject based on the ideXlab platform.
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circular Braiding take up speed generation using inverse kinematics
Composites Part A-applied Science and Manufacturing, 2014Co-Authors: J H Van Ravenhorst, Remko AkkermanAbstract:Circular overBraiding of composite preforms on complex mandrels currently lacks automatic generation of machine control data. To solve this limitation, an inverse kinematics-based procedure was designed and implemented for circular Braiding machines with optional guide rings, resulting in a take-up speed profile for a given Braid angle distribution on mandrels with complex 3D shapes including non-axisymmetric, optionally eccentric cross-sections that can vary in shape and size along an optionally curved mandrel centerline, allowing a curved machine movement. This procedure reduces the problem size, resulting in a short computation time, fit for CAE process chain integration. Numerical control data was generated for a complex mandrel with a specified Braid angle and a Triaxial Braid. A simulation using this control data yields a Braid angle that deviates a few degrees from the specified Braid angle. The simulation was validated experimentally, using the generated instructions to control the Braiding machine. This showed a deviation from the simulated Braid angle of 3 degrees in the centered, non-tapered mandrel regions, up to 10 degrees in tapered regions and an experimental scatter of 7 degrees. The deviation is mainly attributed to the neglect of yarn interaction and guide ring contact friction in the model, leading to an incorrectly modeled convergence zone length.
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Circular Braiding take-up speed generation using inverse kinematics
Composites Part A: Applied Science and Manufacturing, 2014Co-Authors: J. H. Van Ravenhorst, Remko AkkermanAbstract:Circular overBraiding of composite preforms on complex mandrels currently lacks automatic generation of machine control data. To solve this limitation, an inverse kinematics-based procedure was designed and implemented for circular Braiding machines with optional guide rings, resulting in a take-up speed profile for a given Braid angle distribution on mandrels with complex 3D shapes including non-axisymmetric, optionally eccentric cross-sections that can vary in shape and size along an optionally curved mandrel centerline, allowing a curved machine movement. This procedure reduces the problem size, resulting in a short computation time, fit for CAE process chain integration. Numerical control data was generated for a complex mandrel with a specified Braid angle and a Triaxial Braid. A simulation using this control data yields a Braid angle that deviates a few degrees from the specified Braid angle. The simulation was validated experimentally, using the generated instructions to control the Braiding machine. This showed a deviation from the simulated Braid angle of 3 degrees in the centered, non-tapered mandrel regions, up to 10 degrees in tapered regions and an experimental scatter of 7 degrees. The deviation is mainly attributed to the neglect of yarn interaction and guide ring contact friction in the model, leading to an incorrectly modeled convergence zone length. © 2014 Elsevier Ltd. All rights reserved.
Robert K. Goldberg - One of the best experts on this subject based on the ideXlab platform.
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Investigation of a Macromechanical Approach to Analyzing Triaxially-Braided Polymer Composites
AIAA Journal, 2020Co-Authors: Robert K. Goldberg, Brina Blinzler, Wieslaw K. BiniendaAbstract:A macro level finite element-based model has been developed to simulate the mechanical and impact response of Triaxially-Braided polymer matrix composites. In the analytical model, the Triaxial Braid architecture is simulated by using four parallel shell elements, each of which is modeled as a laminated composite. The commercial transient dynamic finite element code LS-DYNA is used to conduct the simulations, and a continuum damage mechanics model internal to LS-DYNA is used as the material constitutive model. The material stiffness and strength values required for the constitutive model are determined based on coupon level tests on the Braided composite. Simulations of quasi-static coupon tests of a representative Braided composite are conducted. Varying the strength values that are input to the material model is found to have a significant influence on the effective material response predicted by the finite element analysis, sometimes in ways that at first glance appear non-intuitive. A parametric study involving the input strength parameters provides guidance on how the analysis model can be improved.
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Full-Field Strain Methods for Investigating Failure Mechanisms in Triaxial Braided Composites
2013Co-Authors: Justin D. Littell, Wieslaw K. Binienda, Robert K. Goldberg, Gary D. RobertsAbstract:Composite materials made with Triaxial Braid architecture and large tow size carbon fibers are beginning to be used in many applications, including composite aircraft and engine structures. Recent advancements in Braiding technology have led to commercially viable manufacturing approaches for making large structures with complex shape. Although the large unit cell size of these materials is an advantage for manufacturing efficiency, the fiber architecture presents some challenges for materials characterization, design, and analysis. In some cases, the static load capability of structures made using these materials has been higher than expected based on material strength properties measured using standard coupon tests. A potential problem with using standard tests methods for these materials is that the unit cell size can be an unacceptably large fraction of the specimen dimensions. More detailed investigation of deformation and failure processes in large unit cell size Triaxial Braid composites is needed to evaluate the applicability of standard test methods for these materials and to develop alternative testing approaches. In recent years, commercial equipment has become available that enables digital image correlation to be used on a more routine basis for investigation of full field 3D deformation in materials and structures. In this paper, some new techniques that have been developed to investigate local deformation and failure using digital image correlation techniques are presented. The methods were used to measure both local and global strains during standard straight-sided coupon tensile tests on composite materials made with 12 and 24 k yarns and a 0/+60/-60 Triaxial Braid architecture. Local deformation and failure within fiber bundles was observed, and this local failure had a significant effect on global stiffness and strength. The matrix material had a large effect on local damage initiation for the two matrix materials used in this investigation. Premature failure in regions of the unit cell near the edge of the straight-sided specimens was observed for transverse tensile tests in which the Braid axial fibers were perpendicular to the specimen axis and the bias fibers terminated on the cut edges in the specimen gage section. This edge effect is one factor that could contribute to a measured strength that is lower than the actual material strength in a structure without edge effects.
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Modification of a Macromechanical Finite Element–Based Model for Impact Analysis of Triaxially Braided Composites
Journal of Aerospace Engineering, 2012Co-Authors: Robert K. Goldberg, Brina Blinzler, Wieslaw K. BiniendaAbstract:Abstract A macro level finite element-based model has been developed to simulate the mechanical and impact response of Triaxially-Braided polymer matrix composites. In the analytical model, the Triaxial Braid architecture is simulated by using four parallel shell elements, each of which is modeled as a laminated composite. For the current analytical approach, each shell element is considered to be a smeared homogeneous material. The commercial transient dynamic finite element code LS-DYNA is used to conduct the simulations, and a continuum damage mechanics model internal to LS-DYNA is used as the material constitutive model. The constitutive model requires stiffness and strength properties of an equivalent unidirectional composite. Simplified micromechanics methods are used to determine the equivalent stiffness properties, and results from coupon level tests on the Braided composite are utilized to back out the required strength properties. Simulations of quasi-static coupon tests of several representative Braided composites are conducted to demonstrate the correlation of the model. Impact simulations of a represented Braided composites are conducted to demonstrate the capability of the model to predict the penetration velocity and damage patterns obtained experimentally.
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Characterization and Analysis of Triaxially Braided Polymer Composites under Static and Impact Loads
Earth and Space 2012, 2012Co-Authors: Robert K. Goldberg, Lee W Kohlman, Gary D. Roberts, Brina Blinzler, Wieslaw K. BiniendaAbstract:In order to design impact resistant aerospace components made of Triaxially Braided polymer matrix composite materials, a need exists to have reliable impact simulation methods and a detailed understanding of the material behavior. Traditional test methods and specimen designs have yielded unrealistic material property data due to features such as edge damage. To overcome these deficiencies, various alternative testing geometries such as notched flat coupons have been examined to alleviate difficulties observed with standard test methods. The results from the coupon level tests have been used to characterize and validate a macro level finite element based model which can be used to simulate the mechanical and impact response of the Braided composites. In the analytical model, the Triaxial Braid architecture is simulated by using four parallel shell elements, each of which is modeled as a laminated composite. Currently, each shell element is considered to be a smeared homogeneous material. Simplified micromechanics techniques and lamination theory are used to determine the equivalent stiffness properties of each shell element, and results from the coupon level tests on the Braided composite are used to back out the strength properties of each shell element. Recent improvements to the model the incorporation of strain rate effects into the model. Simulations of ballistic impact tests have been carried out to investigate and verify the analysis approach.
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effect of microscopic damage events on static and ballistic impact strength of Triaxial Braid composites
Composites Part A-applied Science and Manufacturing, 2009Co-Authors: Justin D. Littell, Gary D. Roberts, Wieslaw K. Binienda, William A Arnold, Robert K. GoldbergAbstract:The reliability of impact simulations for aircraft components made with Triaxial Braided carbon fiber composites is currently limited by inadequate material property data and lack of validated material models for analysis. Methods to characterize the material properties used in the analytical models from a systematically obtained set of test data are also lacking. A macroscopic finite element based analytical model to analyze the impact response of these materials has been developed. The stiffness and strength properties utilized in the material model are obtained from a set of quasi-static in-plane tension, compression and shear coupon level tests. Full-field optical strain measurement techniques are applied in the testing, and the results are used to help in characterizing the model. The unit cell of the Braided composite is modeled as a series of shell elements, where each element is modeled as a laminated composite. The Braided architecture can thus be approximated within the analytical model. The transient dynamic finite element code LS-DYNA is utilized to conduct the finite element simulations, and an internal LS-DYNA constitutive model is utilized in the analysis. Methods to obtain the stiffness and strength properties required by the constitutive model from the available test data are developed. Simulations of quasi-static coupon tests and impact tests of a represented Braided composite are conducted. Overall, the developed method shows promise, but improvements that are needed in test and analysis methods for better predictive capability are examined.
J. H. Van Ravenhorst - One of the best experts on this subject based on the ideXlab platform.
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Circular Braiding take-up speed generation using inverse kinematics
Composites Part A: Applied Science and Manufacturing, 2014Co-Authors: J. H. Van Ravenhorst, Remko AkkermanAbstract:Circular overBraiding of composite preforms on complex mandrels currently lacks automatic generation of machine control data. To solve this limitation, an inverse kinematics-based procedure was designed and implemented for circular Braiding machines with optional guide rings, resulting in a take-up speed profile for a given Braid angle distribution on mandrels with complex 3D shapes including non-axisymmetric, optionally eccentric cross-sections that can vary in shape and size along an optionally curved mandrel centerline, allowing a curved machine movement. This procedure reduces the problem size, resulting in a short computation time, fit for CAE process chain integration. Numerical control data was generated for a complex mandrel with a specified Braid angle and a Triaxial Braid. A simulation using this control data yields a Braid angle that deviates a few degrees from the specified Braid angle. The simulation was validated experimentally, using the generated instructions to control the Braiding machine. This showed a deviation from the simulated Braid angle of 3 degrees in the centered, non-tapered mandrel regions, up to 10 degrees in tapered regions and an experimental scatter of 7 degrees. The deviation is mainly attributed to the neglect of yarn interaction and guide ring contact friction in the model, leading to an incorrectly modeled convergence zone length. © 2014 Elsevier Ltd. All rights reserved.
J H Van Ravenhorst - One of the best experts on this subject based on the ideXlab platform.
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circular Braiding take up speed generation using inverse kinematics
Composites Part A-applied Science and Manufacturing, 2014Co-Authors: J H Van Ravenhorst, Remko AkkermanAbstract:Circular overBraiding of composite preforms on complex mandrels currently lacks automatic generation of machine control data. To solve this limitation, an inverse kinematics-based procedure was designed and implemented for circular Braiding machines with optional guide rings, resulting in a take-up speed profile for a given Braid angle distribution on mandrels with complex 3D shapes including non-axisymmetric, optionally eccentric cross-sections that can vary in shape and size along an optionally curved mandrel centerline, allowing a curved machine movement. This procedure reduces the problem size, resulting in a short computation time, fit for CAE process chain integration. Numerical control data was generated for a complex mandrel with a specified Braid angle and a Triaxial Braid. A simulation using this control data yields a Braid angle that deviates a few degrees from the specified Braid angle. The simulation was validated experimentally, using the generated instructions to control the Braiding machine. This showed a deviation from the simulated Braid angle of 3 degrees in the centered, non-tapered mandrel regions, up to 10 degrees in tapered regions and an experimental scatter of 7 degrees. The deviation is mainly attributed to the neglect of yarn interaction and guide ring contact friction in the model, leading to an incorrectly modeled convergence zone length.
Wieslaw K. Binienda - One of the best experts on this subject based on the ideXlab platform.
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Investigation of a Macromechanical Approach to Analyzing Triaxially-Braided Polymer Composites
AIAA Journal, 2020Co-Authors: Robert K. Goldberg, Brina Blinzler, Wieslaw K. BiniendaAbstract:A macro level finite element-based model has been developed to simulate the mechanical and impact response of Triaxially-Braided polymer matrix composites. In the analytical model, the Triaxial Braid architecture is simulated by using four parallel shell elements, each of which is modeled as a laminated composite. The commercial transient dynamic finite element code LS-DYNA is used to conduct the simulations, and a continuum damage mechanics model internal to LS-DYNA is used as the material constitutive model. The material stiffness and strength values required for the constitutive model are determined based on coupon level tests on the Braided composite. Simulations of quasi-static coupon tests of a representative Braided composite are conducted. Varying the strength values that are input to the material model is found to have a significant influence on the effective material response predicted by the finite element analysis, sometimes in ways that at first glance appear non-intuitive. A parametric study involving the input strength parameters provides guidance on how the analysis model can be improved.
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Full-Field Strain Methods for Investigating Failure Mechanisms in Triaxial Braided Composites
2013Co-Authors: Justin D. Littell, Wieslaw K. Binienda, Robert K. Goldberg, Gary D. RobertsAbstract:Composite materials made with Triaxial Braid architecture and large tow size carbon fibers are beginning to be used in many applications, including composite aircraft and engine structures. Recent advancements in Braiding technology have led to commercially viable manufacturing approaches for making large structures with complex shape. Although the large unit cell size of these materials is an advantage for manufacturing efficiency, the fiber architecture presents some challenges for materials characterization, design, and analysis. In some cases, the static load capability of structures made using these materials has been higher than expected based on material strength properties measured using standard coupon tests. A potential problem with using standard tests methods for these materials is that the unit cell size can be an unacceptably large fraction of the specimen dimensions. More detailed investigation of deformation and failure processes in large unit cell size Triaxial Braid composites is needed to evaluate the applicability of standard test methods for these materials and to develop alternative testing approaches. In recent years, commercial equipment has become available that enables digital image correlation to be used on a more routine basis for investigation of full field 3D deformation in materials and structures. In this paper, some new techniques that have been developed to investigate local deformation and failure using digital image correlation techniques are presented. The methods were used to measure both local and global strains during standard straight-sided coupon tensile tests on composite materials made with 12 and 24 k yarns and a 0/+60/-60 Triaxial Braid architecture. Local deformation and failure within fiber bundles was observed, and this local failure had a significant effect on global stiffness and strength. The matrix material had a large effect on local damage initiation for the two matrix materials used in this investigation. Premature failure in regions of the unit cell near the edge of the straight-sided specimens was observed for transverse tensile tests in which the Braid axial fibers were perpendicular to the specimen axis and the bias fibers terminated on the cut edges in the specimen gage section. This edge effect is one factor that could contribute to a measured strength that is lower than the actual material strength in a structure without edge effects.
-
Modification of a Macromechanical Finite Element–Based Model for Impact Analysis of Triaxially Braided Composites
Journal of Aerospace Engineering, 2012Co-Authors: Robert K. Goldberg, Brina Blinzler, Wieslaw K. BiniendaAbstract:Abstract A macro level finite element-based model has been developed to simulate the mechanical and impact response of Triaxially-Braided polymer matrix composites. In the analytical model, the Triaxial Braid architecture is simulated by using four parallel shell elements, each of which is modeled as a laminated composite. For the current analytical approach, each shell element is considered to be a smeared homogeneous material. The commercial transient dynamic finite element code LS-DYNA is used to conduct the simulations, and a continuum damage mechanics model internal to LS-DYNA is used as the material constitutive model. The constitutive model requires stiffness and strength properties of an equivalent unidirectional composite. Simplified micromechanics methods are used to determine the equivalent stiffness properties, and results from coupon level tests on the Braided composite are utilized to back out the required strength properties. Simulations of quasi-static coupon tests of several representative Braided composites are conducted to demonstrate the correlation of the model. Impact simulations of a represented Braided composites are conducted to demonstrate the capability of the model to predict the penetration velocity and damage patterns obtained experimentally.
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Characterization and Analysis of Triaxially Braided Polymer Composites under Static and Impact Loads
Earth and Space 2012, 2012Co-Authors: Robert K. Goldberg, Lee W Kohlman, Gary D. Roberts, Brina Blinzler, Wieslaw K. BiniendaAbstract:In order to design impact resistant aerospace components made of Triaxially Braided polymer matrix composite materials, a need exists to have reliable impact simulation methods and a detailed understanding of the material behavior. Traditional test methods and specimen designs have yielded unrealistic material property data due to features such as edge damage. To overcome these deficiencies, various alternative testing geometries such as notched flat coupons have been examined to alleviate difficulties observed with standard test methods. The results from the coupon level tests have been used to characterize and validate a macro level finite element based model which can be used to simulate the mechanical and impact response of the Braided composites. In the analytical model, the Triaxial Braid architecture is simulated by using four parallel shell elements, each of which is modeled as a laminated composite. Currently, each shell element is considered to be a smeared homogeneous material. Simplified micromechanics techniques and lamination theory are used to determine the equivalent stiffness properties of each shell element, and results from the coupon level tests on the Braided composite are used to back out the strength properties of each shell element. Recent improvements to the model the incorporation of strain rate effects into the model. Simulations of ballistic impact tests have been carried out to investigate and verify the analysis approach.
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effect of microscopic damage events on static and ballistic impact strength of Triaxial Braid composites
Composites Part A-applied Science and Manufacturing, 2009Co-Authors: Justin D. Littell, Gary D. Roberts, Wieslaw K. Binienda, William A Arnold, Robert K. GoldbergAbstract:The reliability of impact simulations for aircraft components made with Triaxial Braided carbon fiber composites is currently limited by inadequate material property data and lack of validated material models for analysis. Methods to characterize the material properties used in the analytical models from a systematically obtained set of test data are also lacking. A macroscopic finite element based analytical model to analyze the impact response of these materials has been developed. The stiffness and strength properties utilized in the material model are obtained from a set of quasi-static in-plane tension, compression and shear coupon level tests. Full-field optical strain measurement techniques are applied in the testing, and the results are used to help in characterizing the model. The unit cell of the Braided composite is modeled as a series of shell elements, where each element is modeled as a laminated composite. The Braided architecture can thus be approximated within the analytical model. The transient dynamic finite element code LS-DYNA is utilized to conduct the finite element simulations, and an internal LS-DYNA constitutive model is utilized in the analysis. Methods to obtain the stiffness and strength properties required by the constitutive model from the available test data are developed. Simulations of quasi-static coupon tests and impact tests of a represented Braided composite are conducted. Overall, the developed method shows promise, but improvements that are needed in test and analysis methods for better predictive capability are examined.
