A finite-thickness rate-dependent cohesive zone model

This paper presents the formulation of an enriched cohesive element (CE) accounting for the confinement and the viscoelasticity of the adhesive layer under pure mode I solicitation. This formulation follows the structure of the hybrid approach, which combines the use of solid bulk elements (BEs) and CEs. This leads to define the enriched CE as a zero-thickness interface core embedded within two solid bulk adhesive regions. The interface is modelled with a spring whose stiffness is degraded by a damage variable. The bulk adhesive regions are modelled with a standard linear solid (SLS) model with one Maxwell arm. This formulation is implemented using the ABAQUS finite element (FE) software through a custom UMAT material routine, and applied to a single enriched CE as well as to a double cantilever beam (DCB) bonded joint. It is also evaluated numerically against the respective equivalent hybrid models.