Modeling the Nonlinear Deformation and Damage of Carbon-Aramid Fabric Composites in Tension
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MODELING THE NONLINEAR DEFORMATION AND DAMAGE OF CARBON-ARAMID FABRIC COMPOSITES IN TENSION
E. V. Leshkov* and S. B. Sapozhnikov
Keywords: modeling, damage accumulation, hybrid composites, tension, pseudoplasticity, nonlinear deformation. To model the deformation of fabric polymer composite materials highly nonlinear in tension along the warp/ weft threads, an analytical approach is proposed. Based on experimental data and the method of a deformable polyhedron, a tool is developed for an efficient selection of parameters for the model of a fabric composite consisting of equivalent orthogonally stacked unidirectional layers. A new version of the FARGR software module is developed, which makes it possible to design hybrid carbon-aramid fabric composites that show a significant nonlinear (pseudoplastic) mechanical behavior in tension experiments. The strain was measured by the optical (DIC) method. The failure of a carbon fiber layer occurred by fragmentation with stable delamination. In combination with aramid fabrics, such a fracture mechanism leads to the appearance of an extended pseudoplasticity plateau and to a potential insensitivity of such composites to stress concentrators.
Introduction The high durability and rigidity, technological effectiveness and low density of modern composite materials (glass, carbon, and organic plastics) attract the attention of designers in the creation of responsible products of aviation and space engineering and transport systems. The main restriction preventing a wide use wide use polymer composite materials (PCMs) is their inclination to the brittle destruction. In this case, characteristic external indications preceding this destruction and allowing one to prevent the failure, as a rule, are absent. The structural steels and alloys are free from this drawback owing to the nonlinear character of their deformation due to plasticity, but their density is unacceptably high. The South Ural State University, Chelyabinsk, 454080 Russia * Corresponding author; e-mail: [email protected]
Translated from Mekhanika Kompozitnykh Materialov, Vol. 56, No. 5, pp. 867-880, September-October, 2020. Original article submitted March 24, 2020; revision submitted July 27, 2020. 0191-5665/20/5605-0591 © 2020 Springer Science+Business Media, LLC
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Researchers have offered a number of solutions for obtaining composite materials capable of nonlinear deformation and gradual destruction at static loadings. Some of them have paid attention to studying the mechanical behavior of composites based on steel fibers and various polymer matrices [1-4]. These materials exhibit significant failure strains (up to 15 %) and a high resistance to stress concentrations. Nevertheless, the high density makes impossible their employment in aircraft, automotive industry, and space-rocket technics. One of popular approaches to the achievement of a nonlinear behavior of composites is the creation of [0/± φ] angle-ply packages of unidirectional layers [5, 6]. A sufficiently enough efficiency of this way of expansi
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