Stress propagation and debonding effects in impedance-graded multi-metallic systems under impact loading

Abstract

This article investigates the performance of an impedance-graded multi-metallic system. Material combinations of steel–titanium, steel–aluminium and steel–titanium–aluminium are compared against a monolithic steel configuration. The experiments were carried out using a single-stage gas gun, where the target specimens consisted of these material configurations. The targets were subjected to the impact of an aluminium flyer at a velocity of 180 m/s, where elastic waves were expected to propagate through the target. The free surface velocity of the final material in the target was measured and these readings were used to quantify the stresses in the materials. These stress results were compared with the output from two-dimensional axisymmetric numerical models and theoretical equations. The findings of this study indicated that a target configuration with gradual impedance reduction could minimize the magnitudes of both compressive and tensile stresses in the materials, where the latter is critical towards preventing debonding in a multi-material system.