Study On The Dynamic Response Analysis Of Structures With Defect

The warhead component may be deflected by the damage of the cabin, when themissile with a cabin hits a hard target. It would affect the intersection conditions betweenwarhead and the target, thus the terminal effects of the penetrator is influenced. In view ofthat, the free-free beam with defect was investigated in this thesis. The dynamic plasticresponses of the free-free beam with defect and the invalidation issue were studiedcomprehensively by means of theoretical analyses, experiments, and numerical simulations.The quantitative regular pattern of the influence of the cabin on the terminal effects of thepenetrator was obtained. The main contribution of this thesis can be listed as following:The dynamic plastic response of the free-free beam with defect under transverse andoblique impact loads was analyzed theoretically. The effects of the severity and the positionof the defect on the structure dynamic response of the beam and the failure mode werediscussed. The effects of the axial load component on the transient deformation, thedevelopment of plastic hinge, and the final failure state were also studied. The results showthat, the plastic deformation of the free-free beam with defect is mainly concentrated at theposition between the impact point and the position of the defect. The bigger the defect is,the greater the relative rotation of the cross-section is. Thus the plastic failure (even fracture)may appear more easily at the position of the defect; the closer the position of the defect isto the impact tip, the more obvious the defect effect is. Thus the plastic deformation (evenfracture) is more easily generated at the defect cross-section.A free-free beam with defect is designed. The dynamic response of the free-free beamwith defect under transverse and oblique impact loads was studied by means of57mmgas gun experiment system. The experimental data on the effect of the characteristicparameters (defect severity, defect position, and etc.) on the transient deformation and finalfailure mode of the free-free beam were obtained. Meanwhile, the real-time dynamicresponse of free-free beam with defect under the interaction of the transverse load and theaxial load was obtained too.Considering the penetrator with cabin, a structure of the cabin was optimized to meetthe requirements of engineering design, and the penetrator with cabin was designed. Theresearch on the oblique penetration of the penetrator into the concrete target was carried out by means of152mm gas gun experiment system. Based on the theoretical analyses above,an simplified analysis model of the penetrator with cabin was established, and the influenceof the damage strength of the cabin and the combination strength between cabin andpenetrator on the attitude of the missile were discussed. The calculated results agree wellwith the experimental results.The dynamic responses of the free-free beam with defect under transverse and obliqueimpact loads were investigated in the numerical simulations. Thus, the regular patterns ofthe macroscopic distribution of the load at the cross-section of the free-free beam withdifferent impact modes were obtained. The effects of the load type and the defect factors onthe response mode of the free-free beam were discussed. The simulation results agree wellwith the experimental results.