The program was developed to provide an interactive program for fatigue life predictions. The stress spectrum and loading are integrally related. A misestimation in either count leads to severe errors in the estimation of fatigue life. Material properties have inherent scatter because the microstructure of every manufactured item is different. Additionally, certain processes such as coating or chemical etching can affect the material structure significantly.
Safety factors are one of the largest variables in estimating fatigue life.
The materials curve is actually a complex curve composed of the more conservative of a constant life reduction or a statistical life reduction. User inputs are then summed to calculate the total damage and allowable life. The allowable life is determined from the cycles in the input spectrum. The user inputs the fatigue data for the material in use, and the program calculates the statistical variation of the data. Alternatively, a numerical equation for fatigue properties may be entered.