Abstract: The hourglass deformation in the quadrilateral element is discussed in this paper. It is shown that the hourglass modes can be controlled in the computation of large elastic plastic deformation by introducing the hourglass strains and the corresponding stresses. Numerical examples that a high velocity rod impacts a plate target are used to illustrate the effectiveness of the method by the aid of a two dimensional Lagrange program. The results show that the hourglass control proposed here is feasible.

Key words: finite element, computational method, hypervelocity impact