Accession Number:

ADA636999

Title:

Composite Strips with a Circular Stress Concentration Under Tension

Descriptive Note:

Journal article

Corporate Author:

ARMY TANK AUTOMOTIVE RESEARCH DEVELOPMENT AND ENGINEERING CENTER WARREN MI

Report Date:

2004-06-07

Pagination or Media Count:

10.0

Abstract:

A series of tensile experiments were performed on S2 glasstoughened epoxy composite strips with a center hole or a pin joint at various temperatures within the range of -60 deg C and 125 deg C. Four different lay-up configurations each of 24 layers 0 deg, 0 deg90 deg, 45 deg-45 deg and 0 deg45 deg90 deg-45 deg and four different hole diameters 18 , 14 , 38 , 12 were used in both types of specimens. For certain configurations, strain gages were placed at locations around the hole to measure local strains. A loading-displacement curve was constructed for each configuration. The results indicate that the failure of the joints is significantly affected by stacking sequence, temperature, and hole size. The initial slope of the loading-displacement curve, i.e. the stiffness of the joint, increases with decreasing hole diameter or temperature. As expected, the 0 specimens have the highest average stiffness and strength, whereas the 45 deg-45 deg specimens the lowest with the remaining configurations fall somewhere in between. The failure mode, on the other hand, depends only on the fiber orientation in an individual layer. Failure in 0 deg layers is predominantly in shear-out mode whereas tension and shear failures are the main modes in 90 deg and - 45 deg layer, respectively. For the joint specimens, these average stiffness and strength also increase as the distance between the center of the pin joint and the free end of the strip decrease. Finally, a finite element failure model based on the Tsai-Wu tensor theory and progressive damage evolution was also developed. The results indicate that the failure model simulates the experimental data quite well.

Subject Categories:

  • Laminates and Composite Materials
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE