Finite element modeling of 3D spacer fabric: Effect of the geometric variation and amount of spacer yarns

3D spacer fabrics are a type of sandwich structure consisting of two separate multifilament fabric outer layers
linked together with a layer of spacer monofilaments. They have been widely used as energy absorbing materials
and composite reinforcement. The microstructure features and compression behavior of a typical spacer fabric
were investigated experimentally and numerically in this study. Eight unit cells with 64 spacer monofilaments
were reconstructed from scanning of the fabric via Micro X-ray computed tomography (μCT). The geometric
variations of the reconstructed spacer monofilaments were analyzed quantitatively. It was found that spacer
monofilaments in different unit cells are different in length, curvature and torsion. A series of FE models based
on different numbers and combinations of the identified unit cells were created. The FE simulation results showed that the geometric variations of spacer monofilaments have strong influence on the compression behavior, and the model with shorter length, lower curvature and torsion of spacer monofilaments has higher compression resistance. The compression resistance in the densification stage of the fabric increases with increasing the number of spacer monofilaments adopted due to more evident interactions among spacer yarns.
This study provides an in-depth understanding on the compression behavior of spacer fabric.