Debonding analyses of closely spaced Z-pins bridging an unbonded interface

In this study the plasticity, the spatial stress distribution and the debonding behavior of a metallic Z-pin bridging the unbonded interface between two substrates of an elasto-plastic material subjected to shear loading (mode II) are analyzed numerically by the finite element method taking full account of finite strains.

For a weakly bonded Z-pin perpendicular to the substrates the overall average stress-strain response depicts a rather sudden stress drop which is not seen for stronger interfaces in the load range investigated. This stress drop is caused by dual debonding at different locations along the interface between the Z-pin and the substrates.

The plastic zone in the Z-pin initiates in the center and spreads out along the two edges leaving elastic regions in the middle of the ends of the Z-pin. Similar behavior is seen for a Z-pin inclined to have loading against the inclination, while the plastic zone in a Z-pin inclined to have loading with the inclination only grows along one of the two edges of the Z-pin.