Incompatible modes with Cartesian coordinates and application in quadrilateral finite element formulation.

Incompatible modes with parametric coordinates are widely used in finite element method to develop low-order elements with high accuracy. But it leads to unstable results and must be used along with the constant Jacobian matrix technique to assure convergence. The incompatible modes with Cartesian coordinates are proposed as an alternative. The advantage is that the present method can improve the accuracy, assure the convergence of the elements without additional correction technique and greatly reduce the amount of calculation. With this method, a new quadrilateral element IMQ6 is formulated within the quasi-conforming scheme. Both theoretical and numerical analyses are conducted and it is proved that the present incompatible modes improve the element's performance in both precision and efficiency. [ABSTRACT FROM AUTHOR]