Investigation Of Failure Character Of Impact Contact To The Tube

The impact contact between the bullet and freedom tube is a nonlinear structure problem. The dynamic process of impact contact has been investigated by means of nonlinear finite element method in the paper. The researches shown the impact speed, bullet mass, thickness of the tube and diameter/thick ratio of the tube affect the deformation and failure of the tube. For discussed the critical point of elastic deformation translate to plastic deformation when the bullet impact the tube, the critical impact velocity is discussed.In the thesis, the large finite element program LS-DYNA is introduced and used to simulate the deformation of the tube. The results shown that the deformation program of the tube is local dents and firstly occurs at the beginning of impact. With the growth of the dent, the stiffness decreases, and the rigid-body translations and the whole deformations take place. When the impact speed is larger, the phenomenon is clearer. The initial kinetic energy of the missile decreases rapidly to approximate zero during the impact program, and the energy is transferred to internal energy (about 80%)and kinetic energy (about 20%)of the tube.At the central bullet impact contact, the deformation program, final mode, local dent and energy distribution have been investigated and compared with those of beam loading case. Research shown that the influences of deformation mainly come from the material properties, the proportion of diameter to thickness, the proportion of diameter of bullet to that of tube, and the impact speed etc. When yield limit is low but ultimate strength high, the proportion of diameter to thickness is small, and the proportion of diameter of bullet to that of tube is also large, At the case, the deformation program, failure mode and local dent of the tube are close to those of beam. In contrast, when yield limit is high but ultimate strength low, the proportion of diameter to thickness, and the proportion of diameter of bullet to that of tube is small, the deformation course, final mode, local dent and energy distribution of the tube are close to those of tube.