Non-linear finite-element simulations of the tensile tests of textile composites

Abstract

The main aim of this paper is to find if it is possible to identify material parameters using only three force-displacement dependencies, each for a different angle between the loading force and the principal material directions. The tested materials are textiles made of epoxy resin and fibers in the form of a glass plain weave, a glass quasi-unidirectional weave, a carbon plain weave, a carbon quasi-unidirectional weave, an aramid plain weave and an aramid quasi-unidirectional weave. The plain weave has theoretically 50 % of the fibers in the first and 50 % in the second principal material direction. The quasi-unidirectional weave has theoretically 90 % of the fibers in the first and 10 % in the second principal material direction. Seven types of specimens for each material were subjected to experimental tests. The first principal material direction of each material forms an angle between 0°and 90°with a step of 15°with the applied loading force. The results show that it is possible to identify the material parameters with sufficient accuracy using only three force-displacement dependencies for five out of six materials. Keywords: textile composite, cyclic tensile test, material parameters, plasticity, weave locking, identification, optimization Namen~lanka je preiskava mo`nosti ugotavljanja parametrov materiala z uporabo samo treh odvisnosti sila-raztezek pri razli~nem kotu med silo obremenjevanja in glavno smerjo materiala. Preiskovani materiali so tekstil, izdelan iz epoksi smole in vlaken v obliki platnene vezave, kvazi usmerjene vezave, ogljikove platnene vezave, ogljikove kvazi usmerjene vezave, aramidne platnene vezave in aramidne kvazi usmerjene vezave. Platnena vezava ima teoreti~no 50 % vlaken v prvi in 50 % v drugi prednostni smeri usmerjenosti materiala. Kvazi usmerjena vezava ima teoreti~no 90 % v prvi in 10 % v drugi prednostni smeri usmerjenosti materiala. Sedem vrst vzorcev vsakega materiala je bilo preverjeno s preizkusi. Prva glavna usmerjenost pri vseh materialih je bila pod kotom med 0°in 90°s koraki po 15°glede na delovanje sile. Rezultati ka`ejo, da je bilo mogo~e dovolj zanesljivo ugotoviti parametre materiala samo z uporabo treh odvisnosti sila-raztezek pri petih od {estih uporabljenih materialih.

The Non-Linear Sandwich Structure Model for Low-Velocity Impact

“…The constants in Eqs. (1) to (7) are the components of stiffness matrix in form 23 32 13 31 12 21 11 22 33 2 3 1 3 1 2 21 31 23 31 21 32 32 31 12 12 13 23 2 3 2 3 3 1 44 23 55 13 12 21 23 32 13 31 12 23 31 1 2 1 1 1 , , ,…”

“…The non-linear behaviour of the composite material is most obvious when an in-plane shear test is performed. It was proven by performed experiments that the fiberglass fabric materials behave non-linearly in tension along weft and warp direction and also in in-plane shear [7]. Yet it is not usually taken into account in numerical simulations.…”

Experimental and Numerical Investigation of Response of Sandwich Composite Beam Subjected to Low-Velocity Impact

“…The non-linear function with constant asymptote (Eq. 6) is considered in case of plane shear in principal directions 1 and 2 [9]. The following equations describe the resulting stress strain relationship of composite skin…”