Effect of flexural stiffness estimates on the buckling load of delaminated composite beams

A closed-form expression to determine the effective flexural modulus for a laminated composite beam is derived and presented in this paper. An approach based on the established Euler-Bernoulli beam theory with the proposed effective flexural modulus to predict the buckling load of the laminated composite beam is also presented in detail. The problem of a laminated beam with no delamination and that with a single through-the-width delamination is analysed. The results obtained using the current expression are compared with those obtained using existing expressions found in the literature. Results from a non-linear finite-element analysis are also presented and included in the comparison. The parameters investigated include ply orientation, number of layers, delamination length, support conditions, and material property. The comparison of results showed that the current estimated effective flexural stiffness expression yields a good lower bound solution for predicting the buckling load of both the perfect and the delaminated laminated composite beam.