Random Vibration Fatigue: Abaqus Plug-in tool based on Spectral Methods

Fatigue life calculation is crucial for those structures that are applied into a severe dynamic environment, also characterized by high level of randomness. Some commercial software, as Ansys and Comsol, have already built-in tools for random vibration fatigue calculation but Abaqus CAE does not. Hence, this thesis fills this gap, developing a plug-in tool integrated into Abaqus CAE to perform multi-axial fatigue analysis of metal components subjected to random vibration loading. Since this loading is characteristic of high cycle fatigue, first a random stress analysis is perform in Abaqus CAE and then the tool is applied as a post-processor. The literary review suggests some frequency domain methods extremely more efficient compared to time-domain approaches. Thus, they are implemented by Python scripting and incorporated into an Abaqus’s Graphic User Interface. The tool, which can be applied to study random vibration with Gaussian distribution and zero mean, was first validated studying a simple L-plate. The hotspot identification and the maximum damage accumulated were compared against the results obtained with the commercial software Simulia Fe-Safe. Then, a real application case was analyzed and the fatigue effect of the background random vibrations were studied for a cable connectors bracket mounted on a helicopter. Satisfying results were obtained for both cases and they allowed to explore the accuracy and limitations of the tool developed. Moreover, the study permitted to give some suggestion of future works on this field which include non-isotropic materials, critical plane methods, transient random vibration loading and non-Gaussian processes. The tool showed promising results on the hot-spot identification and damage calculation especially for in-phase loading. Hence, it can be an useful tool for the analysis of random vibration fatigue in Abaqus CAE but further improvements are required in case of out-of-phase loading.