Abstract:

Sometimes it is not fully appreciated that even the systems used to perform test procedures themselves often become subjected to significant fatigue loading. This paper presents an analysis of such a system. The analysis demonstrates that fatigue calculation results should be seen as point results from a multi-dimensional distribution of all possible events. For instance, loading level, residual stress level, material quality, surface treatment and surface finish are just a few of the inputs that could exhibit statistical variation. The influence of these possible variations is an important aspect of achieving a robust design. This paper will show how one of these variables, mean stress level, can have a significant effect on achieved life. Sections 1 to 2 provide some technical background. Details of the model analysed are given in section 3. Results are presented in section 4.

Abstract:

The main objective of this project was to perform Stress-Life and crack growth calculations on a typical aircraft main frame section using MSC.Fatigue; thereby demonstrating the possible usefulness of MSC.Fatigue as a general-purpose fatigue analysis tool. The project was based on a medium range passenger aircraft. This fatigue analysis software was used in conjunction with Nastran, Patran and Marc.