Experimental Research And Simulation On Multi-span Pressure Piplines Impacted By Missiles Laterally

This dissertation investigates the influences of internal press and missiles shape on deformation and rupture of a multi-span thin-walled metal tube that struck by a large-mass and slow-speed missile transversely.103 impact tests were conducted on a thin tube (D/t=44) either empty or filled with water using a missile (Dm/t=6) with various nose shapes (flat-nosed, hemisphere-nosed and conical-nosed). Drop hammer rig was used to perform the impact experiment. The impact tests were carried out at the mid-span, and internal pressures of OMPa, 5MPa, lOMPa and 15MPa were used in addition to the tests with water. The critical energy of perforation and the ballistic speed was measured, and the various types of rupture were identified from the section of the test specimens. Force-time curves and internal pressure-time curves were obtained from experiment.The finite element code LS-DYNA was used to simulate the perforation behavior of tubes under impact loading. The results from simulation agree with that of experiments.A theoretical analysis of local damage in a thin ductile tube hit by a flat-nosed missile laterally is developed to predict local failure due to plugging by the beam-on-foundation model. The effect of internal press was considered, and differential equations was obtained which can predict the ballistic speed of the missile which impact the tube filled with water. It can be solved by Runge-Kutta method.