Fatigue Microcrack Behavior under the Influence of Surface Residual Stresses.
Abstract
Direct observations of the surface crack opening displacement (SCOD) of surface and corner cracks were made on samples of Ti-6Al-4V under both cyclic and static loading conditions. The observations were conducted in a specially designed loading stage in-situ in a scanning electron microscope. Cracks from 7-1300 microns have been studied by this technique. Results show that surface residual stresses can significantly affect crack opening behavior, thus crack growth behavior, even when the crack has grown well beyond the zone of residual stress. Concurrent with experimental efforts, an analytical approach has been developed and used to predict SCOD for Mode I surface microcracks based on crack geometry. Correlation with independent results for macrocracks and values for microcracks measured in this program are excellent. In addition, an existing computer program has been successfully used to predict SCOD of corner cracks in the absence and presence of an imposed compressive residual stress field. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1980
- Accession Number
- ADA090561
Entities
People
- Gerald R. Leverant
- John E. Hack
Organizations
- Southwest Research Institute