THE CYCLIC STATE OF MATERIALS AND THE RELATIONSHIP TO MECHANICAL PROPERTIES AND FATIGUE
Abstract
This report contains the results of an experimental and theoretical study relating to the stabilized cyclic state of materials. The objectives accomplished in the program were (1) the experimental verification of the important role played by the cyclic state in fatigue; (2) the correlation of virgin material properties with the cyclic stress-strain curve for four materials (2024-0 and 2024-T351 aluminum alloy plus annealed and hard OFHC copper); and (3) the application of the cyclic stress-strain curve to fatigue analysis. Both constant load-range and constant strain-range fatigue tests up to fatigue-lifes of 10000 cycles were performed under axial loading conditions at speeds of 3 to 15 cycles/minute. Specimens were of circular cross-section with a one-inch gage length and longitudinal strain measurements were made with a dual- range mechanical extensometer. Power-law relationships were developed from the elastic and plastic components of stabilized strains, and these were related to true fracture stress and failure strain. Both cyclic stress-strain envelope curves and cyclic stress-strain curves were developed and employed in fatigue analyses to predict the effect of mean stresses on the fatigue life. A brief series of dual-level cumulative fatigue tests were performed in the low-life fatigue region.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1966
- Accession Number
- AD0808787
Entities
People
- Dewey G. Younger Jr.