Influence factor analysis on anti-whip restraint of ship's main steam pipeline based on LS-DYNA

Abstract

[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.

Keywords

• main steam pipe
• pipe whip restraint design
• LS-DYNA
• U-shaped plate