In this discussion of this paper, it is suggested that in a determination of the accuracy of prediction of penetration response by numerical integration of the conservation equations (using elastic-plastic constitutive equations to represent the behavioral response of earth materials), it may be helpful to compare the results with those from a relevant analytic or closed-form solution. A cavity expansion-based penetration theory and extensions to include conical and ogival-shaped projectiles is discussed as well as its application. The discussers present results for welded tuff, and compare them with the finite difference results given by the authors. Results for Madera limestone are also given. The agreement between analytic solutions and the finite difference code results is good. The deceleration histories computed by the author for specific points within the deformable projectile appear to oscillate about the deceleration traces obtained from the rigid body penetration theory. The finite difference computer such as the one employed, can provide information regarding the stresses and wave motions within both the projectile and the complex geologic materials being penetrated. Analytic solutions (discussed here) are valuable complements to the numerical codes in that the influences of various impact conditions, projectile characteristics, and target material properties on penetrability can be obtained quickly and inexpensively. They are also effective in solving practical problems in which a prediction of the maximum depth of penetration is all that is required.

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  • Accession Number: 00081403
  • Record Type: Publication
  • Report/Paper Numbers: Proc. Paper 11037
  • Files: TRIS
  • Created Date: Mar 26 1975 12:00AM