Research On The Process Of Elliptical Cross-section Projectile Penetrating The Concrete Target

To study the penetration performance of the elliptical cross-section projectile,a series of penetration experiments of semi-infinite grout target were carried out.With the discussion and analysis of experiments results,a penetration theory based on the cavity expansion theory for the elliptical cross-section projectile was established.The penetration depth were calculated and contrasted by using the two cavity expansion theory.In the end,the concrete penetration process were simulated numerically for two typical elliptical cross-section projectiles and one circular cross-section projectile,the research contents and achievements were as follows:(1)Penetration experiments of grout target subjected to elliptic cross-section projectileA series of experiments of semi-infinite grout target impacted perpendicularly by three kinds of projectiles T1?T2 and L1 with the same mass and length were carried out.The cross-sectional area of the elliptical cross-section projectile T1 is equal to the circular cross-section projectile L1,they were used to compare the influence of the cross-section shape on the penetration depth.The elliptical cross-section projectile T1 and T2 have same length of long axis and different length of short axis.They were used to compare the influence of the cross section area on the penetration depth.(2)Penetration resistance model of elliptical cross-section projectile based on the cavity expansion theoryAfter establishing the geometry expression of head shape of elliptical cross-section projectile,the penetration model of elliptical cross-section projectile was presented based on the analysis of the stress characteristics on the stable penetration stage.The penetration depth were calculated respectively by two expansion models.Compared with experiment,the difference between the results of two models was analyzed.(3)Analysis of influence factors of penetration depth of elliptical cross-section projectileThe penetration depth,the change of the velocity and the accelerations of the projectile versus time were calculated by using the presented model based on the one dimensional cavity expansion theory.Then also by using the model,the factors having effect on the penetration depth of the elliptical cross-section projectile,such as the shape of the head,the shape of the cross section and the strength of the concrete target,were calculated and discussed.(4)Numerical simulation on the Penetration of Concrete Target by elliptical cross-section projectileThe selection of the yield surface parameters of the HJC constitutive model and the type of unit failure were discussed.Then a series of simulations were performed for the three different projectiles using the non-linear finite element software LS-DYNA with the improved HJC constitutive model.The penetration depth of the numerical simulation were in good agreement with the experiment.