Mixed finite element model for laminated composite beams

A novel, 6-node, two-dimensional mixed finite element (FE) model has been developed toanalyze laminated composite beams by using the minimum potential energy principle. The model hasbeen formulated by considering four degrees of freedom (two displacement components u, w and twotransverse stress components sz, txz) per node. The transverse stress components have been invoked asnodal degrees of freedom by using the fundamental elasticity equations. Thus, the present mixed finiteelement model not only ensures the continuity of transverse stress and displacement fields through thethickness of the laminated beams but also maintains the fundamental elasticity relationship between thecomponents of stress, strain and displacement fields throughout the elastic continuum. This is animportant feature of the present formulation, which has not been observed in various mixed formulationsavailable in the literature. Results obtained from the model have been shown to be in excellent agreementwith the elasticity solutions for thin as well as thick laminated composite beams. A few results for across-ply beam under fixed support conditions are also presented.