Fatigue as a Design Limitation

Fatigue in metal parts can result from the repeated application of loads considerably below those required for general yielding, that is at levels where stress raisers have their greatest effect. The design limitations thus imposed can often be considerably reduced by introducing some local pre-loading. . A corrosive environment can greatly reduce fatigue strength and the fatigue test data used for a design should, as far as possible, have been obtained under conditions that simulate the anticipated service environment of the part. Another limitation is imposed by material variability, particularly the chance appearance of defects in fatigue sensitive regions. This must be considered as the greatest hazard and emphasizes the importance of effective non-destructive inspection.