A Flory’s only framework for rate-dependent viscoelastoplasticity at large strains

Abstract

Flory's multiplicative decomposition of the deformation gradient is a powerful tool for developing analytical and computational solutions for hyperelastic materials. This approach simplifies the analysis by separating the deformation into distinct components, isochoric and volumetric. This allows for material models that follow the growth condition, preventing unrealistic material self-intersection. Despite being widely used in elasticity, its use as a basis for theoretical developments in plasticity and viscosity is associated with the Kröner–Lee multiplicative decomposition. As a novelty, in this study it is observed that the Flory’s decomposition can be interpreted as the generation of isochoric and volumetric spaces. From this space identification, an additive decomposition of strains can be used, resulting in an alternative framework for the computational modeling of viscoelastoplastic materials. In this framework, the plastic flow direction and the viscous strain rate are taken inside the isochoric Flory’s spaces, simplifying the resulting constitutive models. In particular, a viscoelastoplastic model with isotropic and kinematic hardenings and viscous parameters dependent on the rate and intensity of strains is developed. To demonstrate the effectiveness of the proposed framework, the author developed a specific model suitable for computer simulations using the finite element method. The proposed approach is then validated by comparing representative examples—simulated with an in-house code—to literature experimental data.