Simulation On The Response Of Pipes Impacted By Missiles

Pipes are widely used in the field of production and life. In its use of the process, damage and failure are inevitable. Research on the deformation and failure is of great significance. The software of ANSYS/LS-DYNA and ANSYS parametric design language were used in this paper to build the model of pipes impacted by missiles. Moreover, the deformation and failure of the pipeline were researched. The main work and the conclusions are as follows:(1)Existing research productions were summarized and the shortage of the study was objectively described. The concerned research actuality confirmed the aspects and the emphases of this paper. The research technique route was given meanwhile.(2)The software of ANSYS/LS-DYNA and the basic theory of finite element about impact, including nonlinear theory and the basic theory of plastic materials, were systematically described. The model of the pipe impacted by the missile was builded and its accuracy was verified. The details of the element and material adopted in the model were given. The friction factor and hourglass were also taken into consideration. Two main influence factors of hourglass, grid density and hourglass coefficient, were analysed.(3)Builded the model of the free pipe and the cantilever pipe and maked the grid dependence analysis, then chose1as the element side. Maked a study of the influence of the missile speed, Do/dm and Do/δ on the large deformation of circular pipe. It was found that V and Do/δ had a larger influence on the deformation while Do/dm had little. Under the two kinds of constraint, ω increased with V and Do/δ.(4)Builded the model of elbow bend impacted by the hemisphere missile. Chose1as the element size according to the grid dependence analysis. When hourglass coefficient was0.12, the hourglass energy would meet the demand. The external diameter Do and wall thickness δ of elbow, the diameter dm and quality m of the missile were taken into consideration to study their influence on the critical fracture kinetic energy. The study found that Er increased with the δ、dm and m. Do had little affect on Er. By contrast, the pressture and radius of curvature had obvious influence on it.(5) Builded the model of stiffened elbow bend impacted by the hemisphere missile. Analyzed the grid independence and the rationality of the hourglass energy. Choose0.9as the element size and0.05to be the hourglass coefficient. Studied the influencing factor on the impact resistance, just as the width β, thickness h and position a of the stiffener, the radius of curvature of the elbow bend and the material parameters of the model. The study showed that Er increased first and then decreased with the change of the stiffener’s position and width. The thickness of the stiffener had little influence on Er. Along with the increase of r, Er first increased and then decreased, finally stabilized. The mainly failure mode of the elbow bend included tearing failure and stretching failure. Most of the missile’s kinetic energy changed into the internal energy of the elbow bend. When V≤200m/s, the energy absorption of the elbow bend would increase along with V. When V>200m/s, it would decrease and then barely grew.