Numerical analysis of ductile failure of undermatched interleaf in tension

Ductile failure of an interleaf tension specimen consisting of a metal inte rleaf bonded between two elastic substrates, with a crack located in the ce ntre of the metal, is studied by means of detailed finite element (FE) anal yses. The rate-independent version of the Gurson model is used. This accoun ts for ductile failure mechanisms of micro-void nucleation, growth and coal escence within the framework of a finite deformation plasticity theory. Als o, the rapid evolution of void density due to coalescence, which leads to u ltimate failure, is considered. The effect of the interleaf thickness on fa ilure (crack initiation and limited amount of crack growth) is investigated . The results show that the interleaf thickness affects crack initiation on ly slightly. For all specimens considered, crack initiation takes place at the crack tip. However, after crack initiation, the interleaf thickness aff ects stress and strain distributions significantly. Reducing the interleaf thickness significantly increases the load-carrying capacity. Moreover, red ucing the interleaf thickness increases the maximum hydrostatic stress in t he interleaf, which is no longer developed at the crack tip but at a distan ce far away from the crack tip. The resulting fracture toughness thus decre ases as the interleaf thickness decreases. The shielding of the crack tip d ue to constrained plasticity is observed at higher load levels for interlea f specimens.