Mixed formulated 13-node hexahedral elements with rotational degrees of freedom: MR-H13 elements

A new three-dimensional 13-node hexahedral element with rotational degrees of freedom, which is designated as MR-H13 element, is presented. The propos ed element is established by adding five nodes to one of the six faces of b asic 8-node hexahedral element. The new element can be effectively used in the connection between the refined mesh and the coarser mesh. The derivatio n of the current element in this paper is based on the variational principl es in which the rotation and skew-symmetric stress are introduced as indepe ndent variables. Numerical examples show that the performance of the new el ement is satisfactory.