Derivation of a rectangular finite element for potential problems from consistency criteria

This short paper demonstrates how the matrix for a 4-node potential finite element can be derived from the conditions of 'rigid body movement',dagger symmetry and consistency, and the requirement that the element solve exactly the case of phi = xy. This derivation is intended to be a simple illustration of the ideas of Bergan and others. (C) 1998 John Wiley & Sons, Ltd.