Anisotropic hyper-visco-pseudoelastic damage constitutive model for fiber-reinforced flexible composites considering a temperature effect

Fiber-reinforced flexible composites (FRFCs) and flexible structures are widely used in applications such as soft actuators and biomedical engineering owing to their excellent flexibility and toughness. However, the temperature-sensitive and history-dependent stress-softening effect during cyclic loading–unloading processes cannot be adequately described by the existing theoretical models. In this study, an anisotropic hyper-visco-pseudoelastic damage constitutive model that considers the temperature effect is established to examine the cyclic stress-softening effect and residual-deformation behavior of FRFCs. This model combines the hyper-visco-pseudoelastic theory and continuum damage mechanics while incorporating the influence of temperature. To quantify the degree of damage during cyclic loading–unloading processes, an anisotropic damage evolution law that satisfies thermodynamic constraints is proposed. Additionally, it has been demonstrated that a comprehensive consideration of viscoelasticity, pseudoelasticity, and the damage effect is crucial for accurately describing the cyclic stress-softening effect. Furthermore, a numerical computational framework is presented to analyze the cyclic softening effect and residual deformation in FRFCs and flexible structures. The effectiveness of the constitutive model and numerical computational framework are validated by conducting cyclic loading–unloading experiments at different temperatures. A good agreement is observed between the results of theoretical calculations and numerical simulations and experimental data, confirming the advantages of the proposed constitutive model and numerical computational framework in accurately describing the softening effect and residual deformation of FRFCs, soft biological tissues, and flexible structures with complex structural forms. This study provides theoretical guidance and numerical computation techniques for improving the performance stability of FRFCs and novel flexible structures.