Investigation into the Combined Effects of Compaction, Strain Rate Sensitivity, and Anisotropic Damage of a Geologic Target on the Trajectory Stability of Rigid Penetrators

Abstract

This report presents the results of an experimental investigation into the combined effects of inelasticity and strain rate sensitivity on penetration into geologic or geological derived targets. Both material models and specific computational methods have been developed. A new class of compressible rigid viscoplastic models were proposed to capture the solid-fluid transition in behavior at high strain rates, account for damage/plasticity couplings and viscous effects which are observed in geological and cementitious materials. A hybrid time-discretization was used to model the non-stationary flow of the target material and the projectile-target interaction, i.e. an explicit Euler method for the projectile equation and a forward (implicit) method for the target boundary value problem. At each time step, a mixed finite-element and finite-volume strategy was used to solve the "target" boundary value problem. Specifically, the nonlinear variational inequality for the velocity field was discretized using the finite element method while a finite volume method was used for the hyperbolic mass conservation and damage evolution equations. To solve the velocity problem, a decomposition-coordination formulation coupled with the augmented lagrangian method was adopted. Numerical simulations of penetration into concrete were performed. By conducting a time step sensitivity study it was shown that the numerical model is robust and computationally inexpensive. For the constants involved in the model (shear and volumetric viscosities, cut-off yield limit and exponential weakening parameter for friction) that cannot be determined from data, a parametric study was performed.

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Document Details

Document Type
Technical Report
Publication Date
May 01, 2007
Accession Number
ADA472172

Entities

People

  • Ioan R. Ionescu
  • Oana Cazacu

Organizations

  • University of Florida

Tags

Communities of Interest

  • Weapons Technologies

DTIC Thesaurus Topics

  • Boundary Value Problems
  • Civil Engineering
  • Computational Science
  • Constitutive Equations
  • Elastic Properties
  • Equations
  • Experimental Data
  • High Pressure
  • Materials
  • Materials Testing
  • Mechanics
  • Plastic Properties
  • Porous Materials
  • Scalar Functions
  • Shape
  • Simulations
  • Stratified Fluids

Readers

  • Computational Fluid Dynamics (CFD)
  • Finite Element Method (FEM) for solving Partial Differential Equations (PDEs)
  • Mechanical Engineering/Mechanics of Materials.