Numerical analysis of influencing factors on von-Mises stress of broadband random vibration based on finite element method

Broadband random vibration (BRV) simulation is widely used in structural strength verification. To improve the efficiency of BRV simulation, numerical analysis of influencing factors on the von-Mises stress of BRV simulation is carried out based on finite element method. Then, the effect of excitation frequency range, number of modes and the relationship between number of modes and excitation spectrum on the results of BRV simulation is analyzed, respectively. Finally, an application is carried out to verify the method obtained in this study. Results show that the von-Mises stress is more sensitive to low frequency band excitation. Besides, the reliability of BRV simulation results can reach 95% by excluding the modes whose significance level is less than 5%. Moreover, the accuracy ratio of the BRV simulation results can reach 99% by ensuring the highest mode frequency is not less than the frequency at which the first peak of excitation spectrum appears, and also the mode shape direction should be consistent with excitation direction. Furthermore, the simplified method obtained is verified to be applicable and useful for significantly improving the efficiency of broadband random vibration simulations, and it could also provide a basis and reference for the transient vibration/shock simulation as well. Keywords: Broadband random vibration; finite element method; von-Mises stress; structural strength verification; number of modes; excitation direction