Mechanical Behaviors of Copolymer Elastomers: Experimental Characterization and Constitutive Modeling

We combine experimental analysis and modeling to investigate the complex mechanical behaviors of copolymer elastomers. Experimental studies are conducted to analyze the impact of monomer ratio, strain rate, and loading mode on the response of copolymer elastomers, which reveal the distinct hyperelastic, viscoelastic, damage and self-recovery behaviors of the materials. Based on the experimental observations, we develop a finite deformation hyperelastic-viscoelastic constitutive model, which incorporates multiple discrete relaxation processes. For the hyperelastic process, an extended eight-chain model is employed. Different from the classic viscoelastic model, the strain hardening and damage/recovery mechanisms are also included in the relaxation processes. The model successfully describes the complex mechanical responses observed in elastomers, including quasi-static loading, strain rate effects, and stress relaxation phenomena. Additionally, the model captures the behavior of elastomers during loading-unloading cycles in a reasonable manner. The work offers an efficient theoretical tool for the design and practical application of elastomers.