The goal of this program was to develop a methodology for predicting fatigue lives of structural alloys based on their microstructural characteristics and mechanical properties. Such methodology has been successfully implemented and verified by predicting fatigue lives of the four different variants of the aluminum airframe 7050-T7451 plate alloy and, with modifications, of the butt welds of the ship hull HSLA-80 steels. The key features of the method is the ...
This report contains final results of the quantitative characterizations of the pore and constituent particle morphologies in two different variants of the 7050-T7451 six-inch-thick plate alloys. The purpose of those characterizations was to find volume fraction, size, shape and spatial distributions of both phases and their through-thickness gradients. This is the first ever characterization of this scope which provides unavailable until now data necessary for the predictions of the size ...
The microstructural features of 7050 T7451 aluminum alloy in the vicinity of fatigue cracks and on the crack path were studied to determine which of them influence fatigue crack propagation. The studies included characterization of the full spectrum of microstructural and fracture surface features starting from the largest ones such as roughness and grain type to the smallest such as second phase particles and dislocations. Of all the features studied, ...
The objective of the fatigue life prediction program at UCLA is to (1) ascertain microstructural features relevant to fatigue in aluminum 7050 alloys and develop quantitative methods for their characterizations, (2) characterize initial microstructures and accumulation of microstructural damage during fatigue of 7050-T7451 plate alloys and (3) formulate and test scaling relationships and models relating relevant microstructural features to fatigue damage in aluminum 7050 alloys. Emphases during the reporting period ...
The purpose of the fatigue life prediction program at UCLA is to characterize the accumulation of the microstructural damage during fatigue of the aluminum alloys and to use obtained data in the formulation of the microstructure based stochastic life prediction models. Emphasis during the first year of the program was on the implementation of all required quantitative microscopy techniques and on the characterization of the starting microstructures in the high ...
The purpose of the fatigue prediction program at UCLA is to characterize statistical changes taking place in the microstructure during fatigue of metallic alloys and to develop stochastic life prediction models based on these characterizations. In the three-year Phase I of the program the microstructures and fatigue behaviors of 7050 and 8090 aluminum alloys will be studied. This will be followed by the two-year Phase II during which the life ...
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