Determination of Mixed-Mode Cohesive Zone Failure Parameters Using Digital Volume Correlation and the Inverse Finite Element Method

Abstract

The suitability of an optimisation workflow for the determination of the mixed-mode cohesive zone model parameters using digital volume correlation (DVC) data and the inverse finite element method was examined. A virtual compression experiment of a cylinder with a spherical inclusion was modelled using the finite element method. A bilinear traction separation law with a linear mixed-mode relationship was used to describe the interfacial behaviour. Known mode I and mode II fracture energies, = 20 J/m2 and = 40 J/m2 and damage initiation stress, = 0.09 MPa, were used to generate a target composite debonding behaviour. An objective function,, determined based on the debonding behaviour measurable by DVC was chosen. A full factorial experiment was carried out for the four cohesive parameters and showed that correlation between fracture energies/ damage initiation stresses and is non-linear and discontinuous with multiple local minima. Optimisations initiated at the local minima identified from the full factorial experiment correctly determined the target cohesive fracture energies and damage initiation stresses.