An improved incompatible DSQ element using free formulation approach

This study proposes DSTK, a new incompatible triangular element formulated from a combination of discrete shear constraints, independent transverse shear strains and a free formulation approach. DSTK takes into account transverse shear effects and is valid for thin and thick plates. Furthermore, this element has 3 nodes and 3 DOFs per node (transverse displacement w and rotations Bx and By). The couple between lower order and higher order bending energy is assumed to be zero to fulfil the constant bending patch test. Unifying and integrating kinematic relationship, constitutive law, and equilibrium equations contribute to the independent transverse shear strain expression, which comprises merely the second derivatives of the rotations. The study performs validation based on individual element tests, patch tests, and convergence tests. This study shows that the DSTK element yields good results of various classical benchmark tests for thin to thick plates.