NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Model Determined for Predicting Fatigue Lives of Metal Matrix Composites Under Mean StressesAircraft engine components invariably are subjected to mean stresses over and above the cyclic loads. In monolithic materials, it has been observed that tensile mean stresses are detrimental and compressive mean stresses are beneficial to fatigue life in comparison to a base of zero mean stress. Several mean stress models exist for monolithic metals, but each differ quantitatively in the extent to which detrimental or beneficial effects are ascribed. There have been limited attempts to apply these models to metal matrix composites. At the NASA Lewis Research Center, several mean stress models--the Smith-Watson- Topper, Walker, Normalized Goodman, and Soderberg models--were examined for applicability to this class of composite materials. The Soderberg approach, which normalizes the mean stress to a 0.02-percent yield strength, was shown to best represent the effect of mean stresses over the range covered. The other models varied significantly in their predictability and often failed to predict the composite behavior at very high tensile mean stresses. This work is the first to systematically demonstrate the influence of mean stresses on metal matrix composites and model their effects. Attention also was given to fatigue-cracking mechanisms in the Ti-15-3 matrix and to micromechanics analyses of mean stress effects.
Document ID
20050180567
Acquisition Source
Legacy CDMS
Document Type
Other
Authors
Lerch, Bradley
(NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
August 23, 2013
Publication Date
March 1, 1997
Publication Information
Publication: Research and Technology 1996
Subject Category
Metals And Metallic Materials
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Document Inquiry

Available Downloads

There are no available downloads for this record.
No Preview Available