61 / 2021-03-29 12:09:41

Study on contact and friction dynamics of nuclear polar crane under strong earthquake

rigid-flexible coupling, multi-flexible dynamics, contact/impact, non-smooth, stick-slip

The main purpose of the paper is to investigate the contact and friction problem of the nuclear polar crane/containment vessel system under strong earthquake. Nuclear polar crane(NPC) is one kind of the overhead crane that applied to the nuclear plant, whose special scenarios requires specific earthquake resistant behavior. During a strong earthquake, complex motion modes will be generated between layers of the vertical stacking components. The analysis of the rigid-flexible coupling system involves some challenging contact and friction problems, such as the frictional state judgement, trigger estimate of the isolation mechanism, as well as the calculating of the contacting force, et al. First, a fast modeling strategy has been proposed combining the floating frame of reference and a mass concentration method. In the following, the linear complementarity parametric variables of the non-smooth problem have been reconfigured, with the purpose to develop a comprehensive model which can calculate the transient contact force between flexible bodies with high precision and without changing contact force model. For the time-space multiscale problems, an upscaling method to prevent the rounding error, meanwhile, to prevent the distortion of the contact force affected by the pseudo high frequency oscillations in the numerical solutions. Further, the coulomb friction law has been used to reveal the stick-slip phenomenon under the lock/unlock states of the driving wheels and under the early-warning succeeding / failure conditions. Local dynamics models of the isolation mechanism have also been well established by the velocity decomposition method to reflect the trigger/outrigger statement. During the Solution stage, the time span has been divided into several sections, the integration steps of each section have been well regulated to eliminate the unwanted trial process. Finally, some strong earthquake records are used to calculate the seismic response of the NPC, the stick-slip motions of the system are analyzed.