Tensile stress relaxation behavior of a novel wide‐angle fabric/ EPDM composite at room temperature

Abstract The main purpose of this study is to analyze the fundamental deformation and relaxation mechanisms responsible for the stress relaxation behavior of a novel wide‐angle fabric/ethylene propylene diene monomer (EPDM) composite (W‐60 composite) at room temperature with different initial strain. The designed and constructed stress relaxation test device can test five samples simultaneously. The stress relaxation curves of the W‐60 composite are in general agreement with those of the pure rubber. It is proved again that the wide‐angle fabric has good formability. Through the slope calculation, the stress relaxation curves of the W‐60 composite can be divided into two stages: rapid relaxation stage (RRS) and slow relaxation stage (SRS). The cross‐sections are observed using photographic tracking techniques and CT scans. The stress relaxation mechanism of the W‐60 composite is dominated by the internal physical relaxation. It shows many more correlations under the experiment results for the three‐component Maxwell's model with parallel‐connect nonlinear spring (NS‐TCM model). However, in the mechanical models with more parameters, the computational problem also increases due to the accumulation of local minima, which makes it harder to find global minima. Highlights This study builds stress relaxation testing equipment for flexible composite. This study uses a 7‐day stress relaxation pre‐experiment. The stress retrogradation and elastic recovery have occurred. The deformation and strengthening mechanisms of stress relaxation are revealed. The NS‐TCM model shows a positive correlation with the experimental results.