Finite element analysis of damaged multilayered composite beams with transverse deformability

A third-order Hermitian zig-zag plate theory is presented as development of the classical cubic zig-zag one. In addition to the capabilities of the previous model ((i) transverse shear flexibility, (ii) through-the-thickness continuity of the transverse shear stresses, (iii) traction-free condition on the two external surfaces of the laminate and (iv) possibility to study damaged interfaces), the Hermitian model offers interesting improvements ((i) through-the-thickness linear transverse displacement, (ii) transverse normal deformability, (iii) traction equilibrium condition on the external surfaces and (iv) use of the displacements and transverse shear stresses of the external surfaces as degrees of freedom). The Hermitian zig-zag theory, together with the application of the sublaminates approach, can also be used to obtain more detailed local through-the-thickness distributions of transverse normal and shear quantities. At first a beam finite element based on the Hermitian model has been formulated. Then a discretizing and assembling procedure has been proposed that enables to divide the laminate thickness in a number of elements-sublaminates. A numerical assessment of the method potentialities is presented.