Post-local buckling-driven delamination in bilayer composite beams

Analytical theories are developed for post-local buckling-driven delamination in bilayer composite beams. The total energy release rate (ERR) is obtained more accurately by including an axial strain energy contribution from the intact part of the beam and by developing a more accurate expression for the post-buckling mode shape than that in the work by Chai et al. (1981) and Hutchinson and Suo (1992). The total ERR is partitioned by using partition theories based on the Euler beam, Timoshenko beam and 2D-elasticity theories. Independent experimental tests by Kutlu and Chang (1995) show that, in general, the analytical partitions based on the Euler beam theory predicts the propagation behaviour very well and much better than the partitions based on the Timoshenko beam and 2D-elasticity theories.