Multi-timescale analysis of fatigue crack growth on interfaces via cohesive-zone models

Abstract

The paper describes a new non-linear finite-element formulation to analyse fatigue debonding or delamination, along predefined interfaces, which is multi-scale in time. At the small timescale level, cyclic loading and the related oscillating response are considered in an explicit way, whereas at the large timescale level, both the real loading actions and the related response in terms of displacement and stress fields are replaced with ‘minimum’ and ‘maximum’ functions over the time of the analysis, which also implies doubling the degrees of freedom of the finite-element model. A cohesive-zone model capable of simulating sub-critical damage growth and hysteretic local response is used on the interface. With a conventional cycle-by-cycle incremental procedure, the analysis would require a number of increments significantly higher than the number of cycles, and would be therefore unfeasible for most industrial applications. Instead, with the developed multi-timescale method, the cycle-by-cycle time integrat...