56 results about "Slip band" patented technology

The invention relates to methods and systems to predict fatigue life in aluminum castings. Methods and systems of predicting fatigue life in aluminum castings that combines extreme values of both casting flaws and microstructures with multiscale life models. The multiscale life models account for differing fatigue crack initiation based on the size scale of the defect and microstructure features,including provisions for generally millimeter scale casting flaws, generally micrometer scale second phase particles by cracking or debonding, or submicrometer scale dislocation interactions with precipitates which form persistent slip bands. In the presence of casting flaws, the fatigue initiation life is negligible and the total fatigue life is spent in propagation of a fatigue crack from such flaws. In the absence of casting flaws, however, the total fatigue life is spent in both crack initiation and propagation, except for the case where fatigue cracks initiate from large second phase particles in a coarse microstructure. The extreme values of casting flaws, second phase particles, mean free path through an aluminum matrix or grain sizes are obtained from extreme value statistics whentwo or three dimensional sizes of casting flaws and microstructure features are provided by either direct measurement or analytical prediction. The upper bound flaw or microstructure feature size is calculated by extreme value statistics.