Objectives  To address the high-energy pipe whip design problem faced by the nuclear power plants of ships,

  Methods  LS-DYNA software is used to establish a nonlinear finite element model of the main steam pipe and U-shaped whip restraint device(i.e U-bolt)so as to simulate the dynamic whipping process.

  Results  It is found that the whip restraint rejection force reaches its maximum peak at the primary collision and reduces towards the static support reaction after several collisions. Within a range of 40 -120 mm, the maximum rejection force increases as the initial clearance between the pipe and U-bolt whip restraint device is increased, while the increasing slope gradually reduces and the dynamic magnification factor comes to a limit of 1.74. Within the range of 1.5D-2.5D, the maximum rejection force decreases slightly by 2.5% as the relative axial location between the pipe and U-bolt whip restraint device is increased. Compared with the U-bolt whip restraint, the U-shaped plate can not only reduce the cross-sectional area by 16.3% but also lessen the maximum rejection force by 5.5%.

  Conclusions  The analysis results show that the maximum rejection force of the U-shaped plate whip restraint device has a positive correlation with the initial clearance of the restraint, but there is a limit to the dynamic magnification factor, the square section U-shaped plate whip restraint device has greater bearing capacity.