Research Of The Dynamic Fracture Of The Layered Metal Cylinders Under Inside-Explosive Loading

In the first part of this paper, we paid our main attentions to the effects of the interior interface to the driving and fracturing process of the cylindrical shells under inside-explosive loading. Study the effects of the interior interface to the forming of the fragments. We designed layered metal cylinders for this purpose. In contrast to the one-layer cylinders, there are obvious differences of boundaries, the constraints and the state of the stress lying in the layered cylinders. This will in turn cause the differences of the layered cylinders and the one-layer cylinders with the same thickness under the same level of loading. Because of the complexities of this problem, based on the experiments, also by the use of the theoretical analysis and the numerical simulation, we took quite primary study to this problem.We recorded the dynamic fracture process by the high speed camera. And we got clear photos of the processes. Through reading the pictures, we got the cracking, fracturing and rupturing time of the one-, two- and three-layer cylinder. The two-layer cylinder fractured lately and got the largest initial fragment velocity. This showed that the existing of the interior interface slower the fracture process. The interior pressure along with the crush pressure prevents the leakage of the detonation gas products.We conducted the 3D numerical simulation of the experiments with the nonlinear dynamic analysis software. The computated time history curves of the displacement and the velocity is in good agreement with the experimental results. We have also founded that series of impacts had taken place within the layered cylinders by analyzing the time history of the radial stress of the elements attached to the interior interfaces. According to the development of the cracks and the evolvement of the states of the radial and hoop stress, we gave some primary explains to the observed phenomena of the experiments.In the second part of this paper, we explored the numerical simulation of the long rod projectile penetration into brittle materials. By the use of the JH-2 constitute model to the concrete targets, the Johnson-Cook strength model along with the EOS of the Mie-Gruneisen, we modeled the long rod projectile with hollow penetration into the semi-infinite concrete targets, a experiment which had been carried out by LIU Cangli et al. The computated time history curves of the depth of penetration (DOP), the penetration velocity, the penetration duration and the final penetration depths all fit well with the document. This showed that the methods we have taken can be used to estimate the rigid body penetration into the brittle materials.