ABSTRACT The present paper deals with the optimum shape design of an absolutely rigid impactor which penetrates into a semi-infinite concrete shield. The objective function to maximize is the depth of penetration (DOP for short) of the impactor; in the case of impactors with axisymmetric shapes DOP is calculated using formulas obtained by Ben-Dor et al. [1-3] with the method of local variations  and based on the mechanical model proposed by Forrestal and Tzou . In the present paper we show that using a different class of admissible functions, more general than the axisymmetric one, better results can be obtained. To solve the formulated optimization problem we used a custom version of the particle swarm optimization method (briefly denoted by PSOA), a very recent numerical optimization algorithm of guided random global search. Numerical results show the optimal shape for various types of shields and corresponding DOP; some Ben-Dor et al. [1-3] results are compared to solutions obtained.
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