A Doubly Asymptotic, Non-Reflecting Boundary for Ground-Shock Analysis.

Abstract

This report describes the formulation and implementation of a nonreflecting boundary for use with existing finite element codes to perform nonlinear ground-shock analyses of buried structures. The boundary is based on a first order doubly asymptotic approximations (DAA sub 1) for disturbances propagation outward from a selected portion of the solid medium surrounding the structure of interest. The resulting set of first order ordinary differential equations is then combined with the second-order equations of motion for the finite element model so as to facilitate solution by a staggered solution procedure. This procedure is shown to be computationally stable as long as the time increment is smaller than a limiting value based on the finite-element mass matric and the DAA boundary stiffness matrix. Computational results produced by the boundary are compared with exact results for linear canonical problems pertaining to finite cylindrical and spherical shells. Keywords: Ground shock; Finite elements; Boundary elements; Elastrodynamics scattering; and Doubly asymptotic approximations.

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Document Details

Document Type
Technical Report
Publication Date
Jan 31, 1985
Accession Number
ADA168114

Entities

People

  • Ian C. Mathews
  • Thomas L. Geers

Organizations

  • Lockheed Martin Missiles and Space

Tags

Communities of Interest

  • Energy and Power Technologies
  • Space
  • Weapons Technologies

DTIC Thesaurus Topics

  • Computational Fluid Dynamics
  • Computational Science
  • Computer Programs
  • Construction
  • Differential Equations
  • Engineering
  • Equations
  • Equations Of Motion
  • Grids
  • Ground Shock
  • Integral Equations
  • Mechanical Engineering
  • Mechanics
  • Numerical Analysis
  • Software Development
  • Three Dimensional
  • Two Dimensional

Readers

  • Finite Element Method (FEM) for solving Partial Differential Equations (PDEs)
  • Structural Dynamics.