Finite element model with continuous transverse shear stress for composite laminates in cylindrical bending

In the double superposition hypothesis, the global inplane displacement, which applies to the whole laminate, is enriched by local displacements which are restricted to each individual ply. To avoid the number of d.o.f.s growing with the number of plies, the transverse shear stress continuity is enforced as usual whereas the inplane displacement continuity is “doubly” constrained for two different groups of the local displacement. Based on the hypothesis, a two-node beam element is attempted. The element has the deflection and its derivative as its nodal d.o.f.s. Despite the fact that interpolated deflection is a cubic function of the longitudinal coordinate, the element yields poor accuracy. The cause is sorted out to be an algebraic constraint in the transverse shear. To overcome the constraint, a heterosis node is added. Remarkable improvement of the element accuracy is noted.