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Title: An analytical study of projectile penetration into rock
Authors: United States. Defense Nuclear Agency.
Butler, Dwain K.
Keywords: Projectile penetration
Rock masses
Rock properties
Numerical models
Mathematical models
Publisher: s and Pavements Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Description: Technical Report
Abstract: This report presents the results of a parameter study of projectile penetration into rock using a computer code based on U.S. Army Engineer Waterways Experiment Station modifications and extensions of the Ross-Hanagud penetration theory, which in turn is based on the dynamic cavity expansion theory of Goodier. The theory treats the projectile as a rigid body and the target as an elastic-plastic locking material. The objectives were to gain (1.) a qualitative and quantitative understanding of the factors of importance in rock penetration, (2.) a feel for the depths of penetration which may be attainable, and (3.) an appreciation for the complexities and uncertainties involved. Such an understanding is essential for the design of penetrating weapons for use against targets in rock or in situations in which, because of incomplete target intelligence, the possibility of encountering rock cannot be eliminated. Three rock targets were selected for the parameter study, with properties typical of the low-, medium-, and high-strength rock classifications in Deere and Miller's engineering rock classification scheme. The projectiles considered have ogive noses, a weight range of 250-1000 pounds, a diameter range of 5-10 inches, a caliber radius head range of 2-10, a sectional pressure range of 10-15 psi, and impact velocities of 1000-3000 fps. Using the penetration computer code, five actual field penetration tests into rock targets classified by Deere and Miller's method were simulated. The agreement between the predicted penetration depths and the actual measured depths is quite good. Based on this agreement, it is proposed that the penetration depth for a particular rock target can be bounded given only the engineering classification of the rock. The computer code was also used to calculate rigid body motion-time histories for two rock penetration events for comparison with the published finite difference code calculations of the same events. Good agreement between projectile time histories determined by the two procedures was obtained.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Technical Report

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