Interface corner stress states: plasticity effects

Abstract

When a butt joint fails, failure often initiates in the region where the interface intersects the stress-free edge. Asymptotic solutions for the stress field found at this type of interface corner are presented for an idealized butt joint with rigid adherends and a thin, essentially semi-infinite, adhesive bond. Linear elastic, power law hardening, and perfectly plastic adhesive models are considered. A stress singularity of type σ∼Kr^δ(δ<0) exists when the adhesive is either linear elastic or power law hardening. The impact of material properties on the order of the stress singularity δ and the effect of load level and bond thickness on the value of the interface corner stress intensity factor K are detailed. Slip theory is used to determined the asymptotic, interface corner stress field for a perfectly plastic adhesive. This solution indicates that there is a high level of hydrostatic tension, equal to 1.5 δ _y , in the yielded material along the interface. The three asymptotic solutions are used to construct interface normal stress distributions that closely approximate full, finite element results for an idealization butt joint when small scale yielding conditions apply.