Influence of the lateral confinement on the transverse mechanical behavior of tows and quasi-unidirectional fabrics: Experimental and modeling investigations of dry through-thickness compaction

Fibrous textiles are subjected to dry through-thickness compaction during most of the composites manufacturing processes. Usual tow models implemented in textile numerical simulations do not reproduce the tow widening occurring during the compaction. Nonetheless, this widening (that can reach 10%) would influence the internal microstructure of the considered fabric and its mechanical behavior. This paper proposes a simple mechanical approach to reproduce the width and thickness evolutions experimentally measured during through-thickness compaction of E-glass and carbon tows. Once the material parameters identified on laterally free tows, the tow cross-section model is employed to study the influence of the tow lateral confinement on the transverse mechanical behavior of its corresponding quasi-unidirectional fabric. It is observed that the lateral confinement depends on the quasi-unidirectional stitch tension. This confinement induces a densification of the tows leading to a stiffening of the quasi-unidirectional transverse behavior. This stiffening is well predicted by the proposed modeling approach.