Structural Analysis and Fatigue Life Evaluation of Bracket Type Components Subjected To Random Excitations

Random-vibration fatigue is a common cause of failure in aerospace structures due to the severe dynamic loads in service. This paper presents structural random-vibration fatigue evaluation of hydraulic reservoir system brackets with modal stress approach. Firstly, modal stress analysis of hydraulic reservoir system is conducted to figure out the system behavior in a dynamic structure and to obtain fatigue hotspots. Then, the random-vibration fatigue evaluation in the frequency domain, based on the power spectral density (PSD) approach, is performed at these hotspots. The Dirlik method was chosen to compute fatigue life directly from a PSD of stress. This method is more generally applicable to the wide range of problems, especially where frequency content is not narrow band. Also, topology optimization analysis is realized to obtain optimal bracket design. The density of each element in the design space is defined as design variable. As a result of the topology optimization performed, it has been observed that the new bracket design is more effective design than the current one with regard to have less mass and higher natural frequency.</p