An Enhanced Gradient Regularization of a Damage Model for Elastomers Based on Chain Scission
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Lavoie et al. [1] proposed an incompressible damage model for elastomers by coupling chain scission and polydispersity, enabling a physically motivated description of stiffness degradation under large deformation. However, the large number of material parameters make the model difficult to calibrate and computationally demanding for finite element implementation. Based on this framework, Wang et al. [2] extended it to the compressible case and developed a finite element formulation. Yet the extended model remains within the continuum damage mechanics paradigm. Therefore, it exhibits problems intrinsic to continuum damage mechanics models, such as mesh dependence, limiting its predictive capability and robustness. The objective of this work is to introduce an enhanced gradient regularization into this damage model and to develop a stable finite element implementation suitable for crack propagation analysis under large deformation. We formulate a gradient-enhanced setting by coupling the local kinematic variable which causes chain scission with a nonlocal counterpart governed by a Helmholtz-type equation, thereby providing an intrinsic length scale that regularizes localization and mitigates mesh sensitivity. For the numerical solution, we adopt a staggered strategy inspired by Molnar and Gravouil [3], and propose a Total Lagrangian finite element scheme with a stable time-update procedure for the chain fraction variables implemented in Abaqus via user elements (UEL). The proposed approach preserves the physical interpretation of chain scission and polydispersity while significantly improving numerical stability and reducing discretization dependence. [1] Shawn R. Lavoie, Rong Long, Tian Tang, A rate-dependent damage model for elastomers at large strain, Extreme Mechanics Letters, Vol.8, pp.114-124, 2016. [2] Pinyi Wang, Shawn R. Lavoie, Tian Tang, Finite element simulation of rate-dependent damage in elastomers, International Journal of Fracture, Vol.249, pp. 10, 2025. [3] Gergely Molner, Anthony Gravouil, 2D and 3D Abaqus implementation of a robust staggered phase-field solution for modeling brittle fracture, Finite Elements in Analysis and Design, Vol.130, pp.27-38, 2017.
