Missile Impact with Material Comminution: New Concept - Turbulence Analogy

Abstract

Major Goals: Finite element predictions of missile penetration into concrete and rock after impact has long been unsatisfactory. The standard finite models with constitutive models rate dependent cracking damage, viscoelasticity and crack growth rate based on activation energy concept have always greatly overestimated the depth of penetration into concrete mass and the exist velocity of missile penetrating through a wall. Computational researcher would deny these statements but closer look reveals they have typically introduced artificial dissipation or damping in an empirical way (or based on some non-physical tricks such as artificial increase of strength limit, assuming a physically unjustified phenomenon called dynamic overstress in which the material strength is increased for strain rate > 1, the increase reaching an order of magnitude at strain rates 4.E4 /s to 6.E4 /s. Another, supposedly fancier approach favored by computational researchers has been to increase the strength, by an order of magnitude, by updating the material model with some non-physical computer algorithm, such as a genetic algorithm. In spite of what many computer analysts claimed, and despite their realistically looking beautiful movies, such remedies have been a fiction. They could not predict, or could not be trusted to predict, impact situations very different from those used in the non-physical genetic algorithm or in intuitive empirical dynamic overstress enhancement. Thus the major goal of this proposal was to develop a physically based formulation putting the so-called dynamic overstress on a realistic foundation with predictive capability. Secondarily, it was to combine it with the microplane model, which is a physically realistic nonlinear constitutive model for cracking damage.

Open PDF

Document Details

Document Type
Technical Report
Publication Date
Sep 07, 2018
Accession Number
AD1068253

Entities

People

  • Zdeněk Bažant

Organizations

  • Northwestern University

Tags

Communities of Interest

  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Civil Engineering
  • Computational Science
  • Computer Programming
  • Computer Programs
  • Computers
  • Elastic Properties
  • Engineers
  • Finite Element Analysis
  • Materials Science
  • Mechanical Properties
  • Mechanics
  • Modulus Of Elasticity
  • Molecular Dynamics
  • Physical Theories
  • Physics Laboratories
  • Stress Strain Relations
  • Wave Propagation

Readers

  • Computational Fluid Dynamics (CFD)
  • Structural Health Monitoring of Composite Structures.
  • Theoretical Analysis.

Technology Areas

  • AI & ML
  • AI & ML - Bayesian Inference
  • AI & ML - Machine Learning Algorithms
  • Biotechnology