Advanced miniature mixed mode bending setup for in-situ interface delamination characterization

A novel test frame configuration was developed and employed to design a new miniature mixed mode bending (MMMB) setup for in-situ characterization of interface delamination in miniature multi-layer structures to accomplish full range of mode mixities. This advanced setup is specially designed with sufficiently small dimensions to fit in a scanning electron microscope and under an optical microscope for detailed real-time fracture analysis during delamination. Analysis of the loads in the new test configuration was performed and a special loading configuration was identified which replicates pure mode II loading better than the conventional end notch flexure (ENF) test. Special care was taken to minimize non-linearities, such as friction, the influence of gravity and geometrical non-linearities. Finite element simulation of the designed setup were performed to show its ability to access all loading modes. Preliminary delamination tests conducted on homogeneous bilayer samples under scanning electron microscope (SEM) proved the new setup configuration is capable of measuring the crack length, crack opening profile and crack delamination mechanism in addition to the conventional energy release rate measurements.