The influence of stress relaxation on the compressional properties of weft-knitted spacer fabrics compared to PU foam

Purpose Spacer fabrics are 3D sandwich structures widely used in various industrial applications, including civil engineering, composite reinforcement, automobile manufacturing, medical textiles, sports clothing and equipment and personal protective gear. Due to the widespread usage of spacer fabrics in various applications, they are prone to stress relaxation in applications exposed to constant compressional strain. This research aims to examine the impact of stress relaxation on the compressional properties of spacer fabrics compared to polyurethane foam. Design/methodology/approach Weft-knitted spacer fabrics with four different spacer yarn lengths were produced, and their compressional properties before and after stress relaxation were investigated and compared to those of polyurethane foam. Findings It was found that compressional characteristics of the spacer fabrics before and after stress relaxation are significantly affected by fabric structure. Moreover, stress relaxation changes the compression features of these fabrics, and the highest change percentage occurs in spacer fabric with the shortest spacer length. For all fabric structures, the stress relaxation increases the energy absorption while decreasing the energy absorption efficiency of the fabric. Eventually, all spacer fabrics outperform foam at stresses below 100 cN/cm2. Originality/value The current research shows that stress relaxation changes the compressional properties of spacer fabrics. Therefore, this phenomenon can impact or disrupt the long-term performance of spacer fabrics. To the best of the authors’ knowledge, no study has investigated the effect of stress relaxation on the compressional features of spacer fabrics compared to polyurethane foam.