An in-situ experimental-numerical approach for interface delamination characterization

Abstract

Interfacial delamination is a key reliability challenge in composites and micro-electronic systems due to (high density) integration of dissimilar materials. Predictive finite element models are used during the design and optimization stage to minimize delamination failures, however, they requires a relevant interface model to capture the (irreversible) crack initiation and propagation behavior observed in experiments. Therefore, a set of experimental-numerical tools is presented to enable accurate characterization of delamination mechanism(s) and prediction of the interface mechanics. First, a novel Miniature Mixed Mode Bending (MMMB) delamination setup is presented that enables in-situ SEM characterization of interface delamination mechanisms while sensitively measuring global load-displacement curves for the full range of mode mixities. Accurate determination of the critical energy release rate from the global load-displacement curve requires, however, identification and separation of bulk plastic contributions from the measured total energy dissipation; to this end, an analytical procedure is presented. Finally, a cohesive zone model suitable for mixed mode loading with realistic coupling is presented that can capture the range of interface failure mechanisms from damage to plasticity, as observed in-situ with SEM, as well as a parameter identification procedure. The set of experimental-numerical tools is validated on delamination measurements of a glue interface.

Investigating the influence of the chamfer and fillet on the high-cyclic fatigue strength of adhesive joints of steel parts

“…A small void at the crack front introduces the stress concentration, which will be the source of crack initiation and further debonding. Bridging of a limited number of cracks into the main crack was also observed by Hoefnagels et al [71]. If the load is large enough, unstable debonding will occur until failure.…”