LOW CYCLE FATIGUE BEHAVIOR UNDER BIAXIAL STRAIN DISTRIBUTION.
Abstract
Two structural materials, AMS 4218, an aluminum casting alloy and AMS 6415, a steel alloy, were subjected to a biaxial strain distribution under an R = O cyclic loading mode. R is defined as the ratio of minimum to maximum load. Employing the Von Miss Equivalent Strain criteria to account for biaxial straining, an exponential relationship of steady strain to fatigue life was obtained for both materials with an average power coefficient of .085. Notched material follows this same exponential relationship up to several hundred cycles, after which an increase in power coefficient is realized. Cyclic strain was seen to vary only slightly with mean strain under this loading mode. Conversion of the data to constant mean strain under this loading mode. Conversion of the data to constant steady strain via a Modified Goodman diagram results in an exponential dependency of fatigue life to cyclic total strain with a power coefficient of 0.31. This corroborates the work of M. R. Gross, who stated cyclic total strain rather than cyclic plastic strain is the significant value that yields the same relationship for many different materials when describing low cycle fatigue behavior. Gross's polymaterial power coefficient was 0.32. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 22, 1966
- Accession Number
- AD0482345
Entities
People
- Joseph L. Mattavi
Organizations
- United Technologies Corporation