Local Delamination in Laminates with Angle Ply Matrix Cracks: Part 2. Delamination Fracture Analysis and Fatigue Characterization
Abstract
Constant amplitude tension-tension fatigue tests were conducted on AS4/3501-6 graphite/epoxy (02/theta2/-theta2)s laminates, where theta was 15, 20, 25, or 30 degrees. Fatigue tests were conducted at a frequency of 5 Hz and an R-ratio of 0.1. Dye penetrant enhanced X-radiography was used to document the onset of matrix cracking in the central -theta degree plies, and the subsequent onset of local delaminations in the theta/-theta interface at the intersection of the matrix cracks and the free edge, as a function of the number of fatigue cycles. Two strain energy release rate solutions for local delamination from matrix cracks were derived: one for a local delamination growing from an angle ply matrix crack with a uniform delamination growing from an angle ply matrix crack with a triangular shaped delamination area that extended only partially into the laminate width from the free edge. Plots of Gmax vs. N were generated to assess the accuracy of these G solutions. ne influence of residual thermal and moisture stresses on G were also quantified. However, a detailed analysis of the G components and a mixed-mode fatigue failure criterion for this material may be needed to predict the fatigue behavior of these laminates.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1991
- Accession Number
- ADA253236
Entities
People
- T. K. O'brien
Organizations
- Langley Research Center