Abstract
Separation failure of bonded elastic plates is considered for a class of mathematically one-dimensional structural configurations under various loading and support conditions. These include configurations simulating those of lap joints and ‘patched’ plates in which intermediate edge debonding occurs as a result of applied in-plane tension, three-point loading, and applied transverse pressure. The problems are approached from a unified point of view, as moving boundary problems in the calculus of variations. In this way a self-consistent mathematical model for the intact segment of the composite structure, for the debonded segments of the composite structure, and for the individual plate segments along with the corresponding boundary and matching conditions are obtained, as well as the transversality conditions which define the moving boundaries of a contact zone and of the bonded region itself. The latter establishes the energy release rates for the debonding structures. Numerical results based on analytical solutions then establish delamination paths or threshold curves which predict the onset and propagation characteristics of the evolving structures. These characteristics are seen to be dependent upon the loading conditions, the support conditions, the relative stiffnesses and lengths of the two primitive plates, and on the initial size of the bonded region.