The Role of Fabric Structure on the Compressional Stress Relaxation of Weft-Knitted Spacer Fabrics Compared to PU Foam

Spacer fabrics are unique three-dimensional structures, which are used in various applications due to their specific features. Spacer fabrics are exposed to constant compressional strain in some applications. Consequently, the fabric’s performance will change due to the stress relaxation phenomenon in the fabric structure. This study aims to investigate the effect of spacer fabric’s structure on the compressional stress relaxation of the fabric. To this end, weft-knitted spacer fabrics with different spacer yarn lengths were produced, and their compressional stress relaxation was studied compared to polyurethane (PU) foam. The results reveal that by increasing the length of spacer yarns, the stress relaxation of the fabric decreases, while the maximum energy absorption efficiency increases. Based on the findings, the performance of the spacer fabrics compared to foam depends on the stress level, and all considered spacer fabrics exhibited more energy absorption and efficiency than foam at low-stress levels (lower than 100 cN/cm²). Eventually, knitted spacer fabrics’ compressional and stress relaxation behavior can be precisely estimated using the three-parameter model with nonlinear spring, and the three-parameter Maxwell model with nonlinear spring, respectively.