INTERFACE CORNER STRESS STATES - PLASTICITY EFFECTS

When a butt joint fails, failure often initiates in the region where t he interface intersects the stress-free edge. Asymptotic solutions for the stress field found at this type of interface corner are presented for an idealized but joint with rigid adherends and a thin, essential ly semi-infinite, adhesive bond. Linear elastic, power law hardening, and perfectly plastic adhesive models are considered. A stress singula rity of type sigma similar to Kr-delta (delta < 0) exists when the adh esive is either linear elastic or power law hardening. The impact of m aterial properties on the order of the stress singularity delta and th e effect of load level and bond thickness on the value of the interfac e corner stress intensity factor K are detailed. Slip theory is used t o determined the asymptotic, interface corner stress field for a perfe ctly plastic adhesive. This solution indicates :hat there is a high le vel of hydrostatic tension, equal to 1.5 sigma(y), in the yielded mate rial along the interface. The three asymptotic solutions are used to c onstruct interface normal stress distributions that closely approximat e full, finite element results for an idealization butt joint when sma ll scale yielding conditions apply.