A global energy analysis of impact loaded bi-material strips

A global energy analysis is given of both the static and dynamic energy release rates for a bi-material strip loaded in tension. A steady state crack propagation speed is identified which is determined by the mode II fracture toughness, modulus ratios and thickness of the strips. Initiation times are also found as a function of loading velocity and both these and the steady state speeds are found to compare well with experiments. The initiation phase is also examined using a perturbation analysis and this is found to predict the observed accelerations. Solutions for combined shear and axial loads are also given.