Fatigue Assessment of Explosive Bolts Considering Vibration of Fixtures

Abstract

In order to comprehensively evaluate the safety and reliability of a missile, this paper gives a process of how to perform fatigue assessment for release devices—such as explosive bolts—considering road roughness during its carrying on different classes of roads. Firstly, displacement power spectral density (PSD) function is used to fit models of road surfaces of Class A, C, and E. Taking the surface models as simulations, multi-body dynamics analyses with code ADAMS are performed to obtain acceleration responses of different points on the missile. Loading these accelerations, the corresponding stress distribution of explosive bolts is achieved with FEM code ABAQUS. These loads are counted by rainflow method. Finally, constant life curves with different survival rates are employed to get the S-N curves at different stress ratios and stress concentration coefficients, and fatigue lives of explosive bolts are assessed based on the stress-life method. Afterward, the effect of pretension force on the vibration load is obtained. This paper provides a fatigue evaluation procedure for release devices, which is helpful to raise the reliability of release devices for both design and service procedures.