A Damage-Based Framework for Flexible Cohesive Softening Laws in Abaqus without User Subroutines

Md Jalal Uddin Rumi, Xiaowei Zeng^*
Department of Mechanical, Aerospace & Industrial Engineering, University of Texas at San Antonio, San Antonio, TX, USA
* Corresponding Author: Xiaowei Zeng. Email: email
(This article belongs to the Special Issue: Advances in Fracture Mechanics, Damage Mechanics, and Fatigue Modeling)

Computer Modeling in Engineering & Sciences https://doi.org/10.32604/cmes.2026.079021

Received 13 January 2026; Accepted 16 March 2026; Published online 09 April 2026

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Abstract

Cohesive zone models (CZMs) are widely used to simulate interfacial fracture, where the post-peak softening branch of the traction–separation law (TSL) can strongly influence both the predicted response and the numerical behavior, particularly when the fracture process zone is not small relative to the structure. In Abaqus, however, cohesive elements are natively restricted to bilinear and linear–exponential TSLs, and implementing other softening behaviors typically requires user subroutines, which requires advanced knowledge and limits rapid model development and testing. This work exploits Abaqus’s tabular damage-evolution capability in a different way by constructing the damage variable analytically from a prescribed post-initiation softening response, thereby enabling the direct implementation of a broad class of admissible analytical TSLs, as well as softening curves obtained by fitting experimental data, within the standard Abaqus workflow and without user subroutines. The formulation is developed for pure-mode and mode-independent cohesive behavior with similar interfacial properties in the normal and shear directions and provides a direct mapping between a desired softening response and the corresponding damage evolution. The approach is verified through mode-I and mode-II patch tests, which reproduce the Abaqus-native linear and exponential softening responses exactly under loading and unloading/reloading, and is further assessed using a double cantilever beam delamination benchmark that highlights the sensitivity of the structural response to softening shape while enabling non-native laws, such as modified PPR softening, to be evaluated natively. Finally, simulations of a bioinspired nacre-like composite layer demonstrate how a compact general softening form governs macroscopic stress–strain behavior and fracture patterns in complex microstructures. Collectively, these examples and results establish a practical and robust pathway for implementing and comparing physically meaningful cohesive softening behaviors in Abaqus with minimal overhead.