Fatigue Considerations in Use of Aluminum Alloys

The objective of this research was to predict the fatigue life of a member at 10 percentile levels for SAE-1045 (260HB) steel and 7075-T73 aluminum in aqueous and saline environments. Consideration of environmental effects as rate dependent phenomena promoted the usage of controlled strain rate testing on axial loaded, smooth specimens of each material. It was determined primarily that long-life fatigue resistance is more affected by aqueous and saline environments, and that a simple modification of the fatigue strength exponent adequately described strain-life behavior.

The statistical aspects of scatter in fatigue lives for the 7075-T73 aluminum were evaluated by testing several samples at each of four different strain amplitudes. Agreement between predicted and laboratory test results appears encouraging.