In-plane shear behavior of 3D warp-knitted spacer fabrics: Part II—Effect of structural parameters

The objective of this work is to study the in-plane shear behavior of 3D warp-knitted spacer knitted fabrics by using a picture frame fixture. This part aims to investigate the effects of structural parameters on the shear stress and energy absorption of warp-knitted spacer fabrics. A group of warp-knitted spacer fabrics was produced on a double-needle bar Raschel machine by varying their structural parameters including spacer yarn fineness, fabric thickness, and outer layer structure. The effects of fabric structural parameters on the shear properties of the spacer fabrics were tested and analyzed based on the nonlinear behavior of shear stress versus shear angle and the deformation mechanism. During loading process, the series of surface images were acquired in certain interval at different positions. These images were processed in image analysis software to obtain the full-field displacement and shear angles at chosen points on the surface of test specimen. The potential shear behavior of the fabric was identified with support of the shear stress–strain curve, work done, and efficiency at different shear stages. The regression model was used to establish the elastic deformation properties to obtain the shear results. Advance statistical evaluation and two-way analysis of variance are used to analyze the significance of various factors such as thickness, spacer yarn diameter, and surface structures on energy absorption at maximum shear load and deformation.