Numerical analysis of 3-D solids and composite structures by an enhanced 8-node hexahedral element

A novel enhanced 8-node hexahedral element based on the concept of consecutive-interpolation procedure (CIP) is developed for the analysis of three-dimensional (3-D) linear solids and composite structures. The developed element is named as CHH8 for the brevity. The patch test, locking test, free vibration and heat transfer problems for simple and complex 3-D solids are analyzed. We also consider a 3-D sandwich beam with a core layer made of polyurethane foam and two skin layers made of orthotropic carbon/epoxy composite. The significant difference of the CIP-based approach, as compared with traditional finite element method, is the integration of averaged nodal gradients into interpolation process, representing as a nonlocal feature. With these additional terms, the proposed CHH8 element is able to produce higher accurate approximation of physical fields and smooth gradient fields which are continuous across element boundaries. More importantly, these advantages can be achieved without increasing the problem size, because the degrees of freedom still remain the nodal values. Details about the proposed CHH8 element are presented. To show the accuracy of the developed CHH8 element, numerical examples of 3-D solids and composite structures with simple and complex configurations are considered, and the obtained results are then compared with reference solutions derived from analytical, other numerical methods and experimental data.