Numerical simulation on the dynamic behavior of the bolt connecting the head-cover and stay ring in pumped storage unit

The bolt has been widely used in many kinds of machines, and it shows complex dynamic behavior. This paper analyzed a failure case of pumped storage unit bolt based on the multibody dynamic theory and the fluidstructure interaction theory. The results show that the non-axisymmetric in the circumferential direction of the head-cover and stay ring results in the different of the tensile force and relative stiffness and results significant bending stress on the bolts. In addition, the plastic deformation has occurred in the local area of the thread and there are significant differences in the contact pressure distribution among different cycles, with the contact pressure increasing closer to the inner cycle. The conclusions in this paper provide an in-depth understanding on the dynamic behavior of the bolt, which could be helpful for preventing the failure of the bolt and improving the safety of the pumped storage unit.