Abstract: We present a closed void interface method for computational models with void interface in multi-material problems.It simulates void successfully in complicated engineering.It bases on a technique of changeable mesh topology.It avoids using a straight line to replace a curve in traditional method,and overcomes difficulty in solving contact points.Numerical simulations confirm that the technique is effective.It shows characteristic of no void connectivity.

Key words: changing connectivity of mesh, closed void interface technique, Lagrangian method