Nvvr Murthy Kolluri

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

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.