2016/05/19 by Marco Salviato, Kedar Kirane, Salviato, Marco +7
Engineering · Materials Science · #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Mechanical Behavior of Composites #Natural Fiber Reinforced Composites #Textile materials and evaluations
paper · pdf · doi:10.48550/arxiv.1605.06174
openalex publication_date 2016/05/19 · openalex created_date 2022/10/03 · openalex updated_date 2026/07/28
Design of large composite structures requires understanding the scaling of\ntheir mechanical properties, an aspect often overlooked in the literature on\ncomposites. This contribution analyzes, experimentally and numerically, the\nintra-laminar size effect of textile composite structures. Test results of\ngeometrically similar Single Edge Notched specimens made of 8 layers of 0\ndegree epoxy/carbon twill 2 by 2 laminates are reported. Results show that the\nnominal strength decreases with increasing specimen size and that the\nexperimental data can be fitted well by Bazant's size effect law, allowing an\naccurate identification of the intra-laminar fracture energy of the material.\nThe importance of an accurate estimation of Gf in situations where\nintra-laminar fracturing is the main energy dissipation mechanism is clarified\nby studying numerically its effect on crashworthiness of composite tubes.\nSimulations demonstrate that, for the analyzed geometry, a decrease of the\nfracture energy to 50% of the measured value corresponds to an almost 42%\ndecrease in plateau crushing load. Further, assuming a vertical stress drop\nafter the peak, a typical assumption of strength-based constitutive laws\nimplemented in most commercial Finite Element codes, results in an strength\nunderestimation of the order of 70%. The main conclusion of this study is that\nmeasuring accurately fracture energy and modeling correctly the fracturing\nbehavior of textile composites, including their quasi-brittleness, is key. This\ncan be accomplished neither by strength- or strain-based approaches, which\nneglect size effect, nor by LEFM which does not account for the finiteness of\nthe Fracture Process Zone.\n