Stress Concentration Factor Determination for Various Tensile Test Specimen Configuration by the Finite Element Method Using MSC/PATRAN and MSC/NASTRAN

Abstract

Using MSC/PATRAN for pre- and post-processing of MSC/NASTRAN models, several tensile test specimen configurations were analyzed by the finite element method (FEM). Solid geometry models for each configuration were meshed using both hexagonal elements and tetrahedral elements. In all cases the mesh density was refined till the FEM solution converged. This convergence was verified both by evaluation of the solution's stability as well by various post processing tools available to the engineer within MSC/PATRAN. In each case, the ultimate goal was to determine the stress concentration factor at the specimen s net section. The sensitivity of the three dimensional stress concentration factor to specimen thickness as well as the presence of various through thickness hole sizes in the net section was also explored. In all cases, the resulting three-dimensional solution result was compared to published two dimensional elasticity solutions. While the three-dimensional FEM stress concentration solution compared favorably with the published two-dimensional values for most configurations, the same comparison for specimens with holes in the net section disagreed significantly. The disagreement between three- and two-dimensional analyses was attributed to the transition from plane stress to plain strain near thickness midplane. This work yielded valuable insight for the engineer as to when published handbook data will suffice and when a more detailed FEM solid model analysis is necessary. Additionally, the use of MSC/PATRAN tools for assessing model convergence is also contrasted with more the traditional technique of comparing degrees of freedom to variation in analysis result.

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Document Details

Document Type
Technical Report
Publication Date
Feb 01, 2004
Accession Number
ADA430477

Entities

People

  • Gregory A. Shoales
  • Scott A. Fawaz

Organizations

  • United States Air Force Academy

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  • Air Platforms

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  • Abstracts
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  • Air Force
  • Boundaries
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  • Department Of Defense
  • Elastic Properties
  • Engineering
  • Engineers
  • Finite Element Analysis
  • Geometry
  • Governments
  • Mechanics
  • Stress Concentration
  • Three Dimensional
  • Two Dimensional
  • United States

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