Hybrid-interface finite element for laminated composite and sandwich beams

A novel, 9-node, two-dimensional hybrid-interface finite element has been presented to analyze laminated composite beams based on the principle of minimum potential energy. Fundamental elasticity relationship between the components of stress, strain and displacement fields are maintained throughout the elastic continuum as the transverse stress components have been invoked as nodal degrees of freedom (DOF). Continuity of the transverse stresses at lamina interface is maintained, as the transverse stress components are treated as DOF along-with displacement DOF at interface nodes. Each lamina is modeled using hybrid-interface elements at the top and bottom lamina interfaces and conventional displacement-based 9-node elements sandwiched between these interface elements. Results obtained from the present model have been found to be in excellent agreement with the elasticity solutions for thin and thick laminated composite as well as sandwich beams. Present formulation can be used effectively to combine hybrid-interface elements having transverse stress and displacement components as nodal DOF with conventional 9-node displacement elements for realistic estimate of the transverse stresses.