Mechanics Based Design of Structures and Machines, 35: 1–14, 2007 Modification of the Method of Local Variations for Shape Optimization of Penetrating Impactors Using the Localized Impactor/Shield Interaction Models # G. Ben-Dor, A. Dubinsky, and T. Elperin Department of Mechanical Engineering, Pearlstone Center for Aeronautical Engineering Studies, Ben-Gurion University of the Negev, Israel Abstract: Implementation of the localized interaction models for description of impactor-shield interaction implies that the depth of penetration of the impactor (body of revolution) is represented as an integral over a parameter (the velocity of the impactor) with the integrand depending on this parameter and on integral which in its turn depends on this parameter and on the unknown function determining the shape of the impactor. We suggest a modification of the method of local variations of Banichuk and Chernous’ko for determining the shape of the impactor with the maximum depth of penetration. The suggested optimization procedure can be employed for arbitrary localized interaction models. The latter allows a practically unlimited freedom in choosing a particular localized interaction models for shape optimization of penetrators. As an example of application of the method we studied a version of the localized interaction models with friction coefficient depending on sliding velocity. Keywords: Impactor; Method of local variations; Optimization; Penetration. INTRODUCTION Many engineering models for high-speed penetration modeling belong to the class of localized interaction models (LIMs; Ben-Dor et al., 2005, Received October 30, 2006; Accepted November 13, 2006 # Communicated by N. Bamchuck. Correspondence: T. Elperin, Department of Mechanical Engineering, Pearl- stone Center for Aeronautical Engineering Studies, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105, Israel; E-mail: elperin@.bgu.ac.il