An existing one-dimensional, non-steady analysis of an eroding kinetic energy penetrator will be used as the basis to develop a damage assessment model. The model presently accounts for the effects of penetrator fineness ratio, compressibility and standing shocks. It will be expanded in scope by refining the present backface model to predict perforation and spall. Because the model is based on the A.R.A.P. integral theory of impact it has the capability to treat situations not readily accessible to finite element codes, i.e., advanced, non-metallic composite targets. A relatively simple one-dimensional model is used as it aids in the understanding of penetrator/target interaction and allows for the economic computation of a variety of cases. In this program, the development of the damage model is guided by multi-dimensional numerical simulation codes and by laboratory experiments. The code will be demonstrated by application to a problem of practical interest: an underwater spaced array.