Compression behavior of warp-knitted spacer fabric based on simplified finite element method

Warp-knitted spacer fabrics (WKSF), with their unique structure and excellent energy absorption properties, are widely utilized in the automotive industry, medical field, and aerospace sectors. However, during practical applications, WKSF undergo repeated compression, which can lead to compressive fatigue of the spacer yarns and consequently cause the WKSF to undergo irreversible deformation, which subsequently affects its performance and appearance. Therefore, to enhance the compressive properties of WKSF and investigate the mechanisms of plastic failure, this study used a warp knitting double needle bar raschel machine to fabricate a WKSF with a thickness of 20 mm. Through fabric structure analysis, we developed a unit cell model consisting of 32 fibers and a more comprehensive analysis model with 320 fibers to quantitatively assess the geometric changes of the WKSF during the compression process. Furthermore, we experimentally studied the performance changes of the WKSF under different compression speeds, various compression strains, and 1000 cycles of loading. By integrating experimental test with the finite element method, we have conducted an in-depth study of the compression process of WKSF, simulating the displacement U, Von Mises stress distribution, and plastic compression failure behavior during compression. By comparing data on Von Mises stress, equivalent plastic strain (PEEQ), and energy density distribution (SENER), we can clearly observe the performance of spacer yarns under compression conditions, providing significant insights into the underlying plastic failure mechanisms of WKSF's. This study not only enriches the theoretical framework for WKSF compression but also lays a solid foundation for improving its performance and extending its applications.