PSI - Issue 17

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000

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Procedia Structural Integrity 17 (2019) 58–63

ICSI 2019 The 3rd International Conference on Structural Integrity Numerical Analysis of Auxetic Yarn with Composite Matrix Interaction Michał Kwietniewski a * , Danuta Miedzińska a a Military University of Technology, Faculty of Mechanical Engineering, Department of Mechanics and Applied Computer Science, Gen. S. Kaliskiego Street 2, 00-908 Warsaw, Poland A modelling method of auxetic yarn (Helical Auxetic Yarn type) cooperating with the composite matrix was presented. The two component yarn surrounded by a flexible material is a fragment of composite, that consists of an auxetic fabric as a reinforcement and a flexible matrix. Such composite can be used in energy absorbing structures. The HAY as an auxetic material is characterized by a negative Poisson ’s ratio. The stiff fiber spirally wrapped around the elastic core with a larger diameter gives this structure anomalous behaviour during tensile. Stretching of such yarn increases its dimensions in transverse directions. Helical Auxetic Yarns are sewn into fabric which is durable, flexible and light. The conducted analysis of the fragment of the composite reflecting one yarn allows for pre-adjustment of values of matrix material parameters. The purpose of the modelling is to determine the values of a composite matrix parameters that should allow the effective work of auxetic yarn. If the matrix were too stiff, it would block the capability of bending the core fiber during stretching and the auxetic phenomenon would be cancelled. The key problem is performing these analyses with appropriate value of the Young's modulus of the composite matrix material to get the optimal composite structure. Finite Element Method analyses were conducted in LS-Dyna solver. Discrete model was build using hexagonal, solids elements. It was assumed that the matrix completely filled the spaces between the fibers, and at the outside it had the shape of the cylinder. The choice of such matrix shape allowed to carry out proper interpretation of the displacement values of nodes located at the boundary plane of the matrix model. The displacement of these nodes determines the proper work of the auxetic yarn. Relevant constitutive material models were used to reflect the work of the aramid wrap as well as the elastomeric core and matrix. Nodal displacement was applied to the one of the end of model to simulate tension under static conditions. FEM analyses were based on the implicit method, which is well suited for simulation of static processes, where final state is the most interesting. Based on the results of the conducted analyses, it was possible to choose the appropriate matrix material of the composite without preparation of many composite samples with various elastomer matrix and carrying out many experimental tests. ICSI 2019 The 3rd International Conference on Structural Integrity Numerical Analysis of Auxetic Yarn with Composite atrix Interaction Michał Kwietniewski a * , Danuta Miedzińska a a Military University of Technology, Faculty of Mechanical Engineering, Department of Mechanics and Applied Computer Science, Gen. S. Kaliskiego Street 2, 00-908 Warsaw, Poland Abstract A modelling method of auxetic yarn (Helical Auxetic Yarn type) cooperating with the composite matrix was presented. The two component yarn surrounded by a flexible material is a fragment of composite, that consists of an auxetic fabric as a reinforcement and a flexible matrix. Such composite can be used in energy absorbing structures. The HAY as an auxetic material is characterized by a negative Poisson ’s ratio. The stiff fiber spirally wrapped around the elastic core with a larger diameter gives this structure anomalous behaviour during tensile. Stretching of such yarn increases its dimensions in transverse directions. Helical Auxetic Yarns are sewn into fabric which is durable, flexible and light. The conducted analysis of the fragment of the composite reflecting one yarn allows for pre-adjustment of values of matrix material parameters. The purpose of the modelling is to determine the values of a composite matrix parameters that should allow the effective work of auxetic yarn. If the matrix were too stiff, it would block the capability of bending the core fiber during stretching and the auxetic phenomenon would be cancelled. The key problem is performing these analyses with appropriate value of the Young's modulus of the composite matrix material to get the optimal composite structure. Finite Element Method analyses were conducted in LS-Dyna solver. Discrete model was build using hexagonal, solids elements. It was assumed that the matrix completely filled the spaces between the fibers, and at the outside it had the shape of the cylinder. The choice of such matrix shape allowed to carry out proper interpretation of the displacement values of nodes located at the boundary plane of the matrix model. The displacement of these nodes determines the proper work of the auxetic yarn. Relevant constitutive material models were used to reflect the work of the aramid wrap as well as the elastomeric core and matrix. Nodal displacement was applied to the one of the end of model to simulate tension under static conditions. FEM analyses were based on the implicit method, which is well suited for simulation of static processes, where final state is the most interesting. Based on the results of the conducted analyses, it was possible to choose the appropriate matrix material of the composite without preparation of many composite samples with various elastomer matrix and carrying out many experimental tests. Abstract

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. © 2019 The Auth r . Published by Elsevier B.V. © 2019 The Authors. Published by Elsevier B.V.

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. * Corresponding author. Tel.: 261 83 7867. E-mail address : michal.kwietniewski@wat.edu.pl * Corresponding author. Tel.: 261 83 7867. E-mail address : michal.kwietniewski@wat.edu.pl

2452-3216  2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. 10.1016/j.prostr.2019.08.009