A hybrid element model for structural mechanics problems

We present in this paper a hybrid element model, which is a type of Metis element (mongrel element) derived from a two-field variational functional. In this model, the assumed boundary displacement field is unisolvent, and the plausible equilibrated stress field within each element is derived using an Airy's stress function. Based on this theoretical framework, an 8-node isoparametric finite element is developed. Examples are presented to illustrate the effectiveness of the proposed finite element model, and it is validated by comparing its results with analytical solutions and those of existing element models in literature. Results obtained from the current model are found to agree well with analytical solutions, and showed that it is less sensitive to geometric distortion than standard finite elements and provides highly accurate stress calculations. The proposed model offers a promising approach to structural mechanics problems, wherein finite element meshes are highly distorted and analysis requires accurate calculations of stresses.