Variable-node axisymmetric solid element and its application to adaptive mesh refinement

This paper presents an effective application of a variable-node axisymmetric solid element<br />designated as AQV (Axisymmetric Quadrilateral Variable-node element). The variable-node element with<br />physical midside nodes helps to overcome some problems in connecting the different layer patterns on a<br />quadrilateral mesh in the adaptive h-refinement. This element alleviates the necessity of imposing<br />displacement constraints on irregular (hanging) nodes in order to enforce the inter-element compatibility.<br />Therefore, the elements with variable mid-side nodes can be used effectively in the local mesh refinement<br />for the axisymmetric structures which have stress concentrations. A modified Gaussian quadrature should<br />be adopted to evaluate the stiffness matrices of the variable-node elements mainly because of the slope<br />discontinuity of assumed displacement within the elements. Some numerical examples show the usefulness<br />of variable-node axisymmetric elements in the practical application.