A new and simple locking-free triangular thick plate element using independent shear degrees of freedom

In this paper, a new locking-free element triangular thick plate element with 9 standard kinematic degrees of freedom and 6 additional degrees of freedom for shear strains (TTK9S6) for analyzing plate/shell structures of thin or thick members is developed. With an appropriate use of independent shear degrees of freedom (DOF), the shear locking problem is completely removed without inducing any numerical expediency such as reduced integration, assumptions of strains/stresses, nor are additional efforts needed to stabilize spurious zero energy modes. Compared to existing triangular shear-deformable plate elements that pass patch tests for both thick and thin plates, the formulation of the present TTK9S6 element is very simple-and perhaps as simple as possible. A number of numerical examples are tested showing the convergence and accuracy of the TTK9S6 element.