Composite Strips with a Circular Stress Concentration Under Tension
Abstract
A series of tensile experiments were performed on S2 glass/toughened 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 deg/90 deg], [45 deg/-45 deg] and [0 deg/45 deg/90 deg/-45 deg] and four different hole diameters: 1/8 , 1/4 , 3/8 , 1/2 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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 07, 2004
- Accession Number
- ADA636999
Entities
People
- B. B. Raju
- B. M. Liaw
- C. K. Cheung
- F. Delale
Organizations
- United States Army Tank Automotive Research, Development and Engineering Center