An inverse analysis of cohesive zone model parameter values for ductile crack growth simulations

• An inverse analysis procedure is developed to identify cohesive zone parameter values for ductile crack growth simulations.
• Key points on the Mode I load–crack extension curve are used to create the error function in inverse analysis.
• The inverse analysis procedure is robust and converges fast.
• Mixed-mode simulation results using identified CZM parameter values are validated by experimental measurements.

An inverse analysis using a modified Levenberg–Marquardt method is carried out to identify cohesive zone model parameter values for use in 3D finite element simulations of stable tearing crack growth events in Arcan specimens made of 2024-T3 aluminum alloy. The triangular cohesive law is employed in the simulations. The set of cohesive parameter values is determined in the inverse analysis by minimizing the difference between simulation predictions of key points on the load–crack extension curve with experimental measurements. From three different initial values, similar cohesive parameter value sets are reached. Using these sets of values, the predicted load–crack extension curves and the variation of a generalized crack tip opening displacement (CTOD) with crack extension for mixed-mode loading cases are compared with experimental measurements, which provide a validation of the cohesive parameter values and of the finite element simulation predictions.