Thermo-mechanical instabilities in patched structures with edge damage

The problem of thermal buckling of patched beam-plates possessing (stationary) symmetric edge detachment is studied. The analytical model is adapted from recent work of the authors and accounts for a (propagating or full) contact zone adjacent to the bonded region. The associated geometrically non-linear problem is recast in a mixed formulation that lends itself to exact analytical solutions in terms of a membrane force, the value of which is determined from an integrability condition. Stability analyses are performed on the equilibrium configurations, revealing salient behavior of the composite structure under thermal loading. Results from numerical simulations indicate the occurrence of sling-shot buckling in the partially detached structure, where the structure is seen to dynamically buckle from one configuration to another configuration (which corresponds to deflection in the opposite sense.) This previously established phenomenon has been shown to be pervasive in intact layered structures under thermal loading. The results of the present study also unveil the occurrence of a, here-to-fore, unreported phenomenon the authors refer to as “buckle-trapping”. During this event, the structure becomes trapped between two unstable equilibrium configurations whose deflections are of opposite sense. This phenomenon is associated with the physical change of the structure through deflection, and its related instabilities. These instabilities, and the associated sequence of events, are seen to be a function of the relative size of the detached region, the support conditions and, consequently, the nature of the contact zone and/or its dissolution.