Vibration fatigue analysis of military wheeled vehicle components

In this study, vibration fatigue analyses are carried out according to military standards on the components mounted on military wheeled vehicles. As an experimental verification, an electrical box bracket attached to a military vehicle is used. Vibration fatigue analyses are carried out both in the time-domain and the frequency-domain. Proposed methods are compared with the results of the vibration fatigue test. MIL-STD-810G Test Standard prepared by the US Department of Defense is used to define the vibration levels. The electrical box bracket is simulated by Finite Element Method. Modal and random vibration analyses are carried out under the specified loads on the 3-D model of electrical box bracket. In the frequency domain, the fatigue life is calculated according to Narrow-Band, Wirsching-Light, Ortiz-Chen, Tunna, Alpha_0.75 , Tovo-Benasciutti and Dirlik methods. In the time domain, the stress-time histories are synthesized according to the response power spectral densities obtained on the possible fracture points. After checking the conformity of the synthesized time histories to the reference response power spectral densities, the cycles are counted according to the rainflow algorithm. In the time-domain, the fatigue life of the electrical box bracket is calculated by accumulating the damage of rainflow cycles according to Palmgren-Miner cumulative damage rule. Maximum damage on the bracket is observed on the longitudinal axis on the vehicle. The experimental fatigue life of the electrical box bracket is observed in the vibration tests under the loads defined in this direction. The fatigue life predicted by different methods in the frequency-domain and the time-domain are compared with the experimentally observed fatigue life.