A Representative Volume Element Based Micromechanical Constitutive Modeling of Woven Composites
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A Representative Volume Element Based Micromechanical Constitutive Modeling of Woven Composites A.M. Rajendran 1, R. Valisetty 2, and R. Namburu 2 1 U.S. Army Research Office, Research Triangle Park, NC 27709-2211, U.S.A. 2 U.S. Army Research Laboratory Aberdeen Proving Ground, MD 21005-5067, U.S.A. Y.A. Bahei-El-Din Department of Mechanical, Aerospace & Nuclear Engineering Rensselaer Polytechnic Institute Troy, NY 12180-3590, U.S.A. ABSTRACT This paper presents a computationally intensive, multiscale constitutive model for 3D-woven composites exhibiting progressive damage. The model is based on analysis of a representative volume element (RVE), which is derived from the actual woven architecture. The link between the local phenomena and the overall response is described by a transformation field analysis (TFA) in terms of stress concentration factors and influence function, which reflect the microgeometry and properties of the constituents. In this way, the local geometric and physical effects are represented in the model with substantial details so that the local stress and strain fields and the overall response could be accurately computed. It seems to be a reliable approach to capture the effects of the material heterogeneity and damage on wave dispersion and attenuation in shockwave problems. The RVE/TFA-based constitutive model was implemented into the DYNA finite element code, and simulations of shock and impact problems were performed to describe the various damage mechanisms. The TFA model is computationally intensive and requires massively parallel computing. This paper examines the effects of the local field representation, and the in situ damage phenomena on the overall response.
INTRODUCTION Woven composites come in a variety of weaves, orthogonal, 2-dimensional, 3-dimensional, stitched, etc. They come with different fibers: glass, Kevlar, or carbon, and with different matrices. Since these composites can be made in a variety of weaves, braids, fibers and matrices, to effectively use these materials in short duration impact applications, one should be able to relate the weave construction details to the overall structural response. Structural analysis techniques, which hope to provide reliable predictions for the behavior of textile composites, must therefore address the evolution of local phenomena and their effects on the overall response. This is particularly important in shockwave propagation problems where modeling the material heterogeneity and the evolution of damage plays a major role in capturing wave dispersion and attenuation. The effects of shock-induced damage on the shock stress as well as the overall response of woven composites are poorly understood due to the lack of detailed modeling of the microstructures and the underlying deformation phenomena. The elastic–
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viscoplastic or viscoelastic constitutive models utilized in finite element analyses often fail to capture the effects of heterogeneities on the shock wave response of composite materials and laminates, parti
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