Computational Fatigue Life Prediction of Welded and Non-welded Ground Vehicle Components

A variable amplitude computational fatigue life prediction method was developed for use with welded and/or non-welded components for use with the ground vehicle industry. The method is principally applicable to the pre-prototype and prototype iteration/optimization design stage. For welded components, the method incorporates the hot-spot stress approach developed by the European community for off-shore structures. For non-welded notched components, the method incorporates the local notch strain approach. Finite element stress-strain analysis using the ANSYS program combined with dynamic simulation utilizing the DADS program transforms a vehicle wheel input, in the form of a terrain surface description, to the principal hot spot stress or nominal principal strain at each node of interest as a function of time. Rainflow counting and linear damage accumulation along with specific material or weld classification properties are incorporated. Verification of the welded and non-weld fatigue life prediction methods were made using welded cruciform specimen and keyhole specimen variable amplitude test results obtained from the literature. Fatigue life predictions were also made at critical locations on the HMMWV military vehicle subjected to simple terrain wheel input. The computational fatigue life prediction methods developed have been implemented in the Integrated Analysis Capability (IAC) command processor and data base system. This program interfaces well established analysis tools and provides the engineer control of the complex interdisciplinary process.