Elasto-plastic analysis of the single cantilever beam adhesion test

Double cantilever beam and associated tests are much used to characterise structurally bonded systems. Use of these, usually, implicitly assumes that the bulk adherends remain elastic during separation (neglecting local effects at the crack front). However, in many pragmatic situations, strength of adhesion is required for systems in which (at least) one adherend becomes partially plastic during fracture, either due to low elastic limit or thinness of the substrate (e.g. the ‘climbing drum’ test). We present here a single cantilever beam test, in which only one adherend is sufficiently flexible to bend appreciably under load. In particular, we consider behaviour of the system when the applied bending moment is sufficiently great to induce elasto-plastic behaviour in the said adherend. Tests performed on a model aluminium/epoxy system have been monitored using optical and mechanical techniques. The situation has been analysed assuming ideal elasto-plastic behaviour of the substrate.

► New adhesion test analysis, useful for elasto-plastic substrates.
► Test suitable for aerospace materials, such as thin aluminium.
► Fracture energy given by unusual form (dependence on load).