Two-layer beams (i.e., bimaterials) under thermomechanical stress are prone to peeling or delamination at the free edges. The self-equilibrating peeling stress gives rise to a peeling moment Mp close to the free ends. A simple and exact formula for Mp is presented in which the sign of Mp indicates whether the beam is prone or resistant to delamination. The effect on both the sign and magnitude of Mp of the flexural rigidities of both layers is examined. As the stiffness of one layer becomes dominant, the magnitude of the differential rigidity converges to one-half the thickness of the opposite layer.

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