Study On Dynamic Characteristics Of Pressure Vessels With Flat-wound Steel Ribbon Subjected To Explosion Loading

A pressure vessel with flat-wound steel ribbons is a new kind of pressure vessel. Many such vessels are serving in industrial fields, such as petroleum, chemical industry, mechanical industry, etc. Many scholars have studied static mechanics characters of ribbon vessels in experimental and theoretic aspects and many important results are obtained. Especially, in the field of petroleum and chemical industry the vessels often work under high temperature and pressure circumstances. It is possible that the ribbon vessels are subjected to inner explosion loading in the process of utilizing practically because of bigger inner pressure. At present, disadvantages of the monobloc containment vessels used widely appear. Consequently, it is possible that some problems which are caused by the monobloc thick-walled containment vessel are solved through using the flat ribbon helically wound structure. Furthermore, in the public safety, because terroristic activities turn to more and more frequent since "9·11", some devices are needed to deal with explosive substances in public concourses, such as train stations, airports, post offices, wharfs and squares, etc. It has well foreground that the ribbon vessels with smaller volumes and low costs are developed to that type of vessels. But, there are few papers about dynamic characteristics of pressure vessels with flat-wound steel ribbon subjected to explosion loading. In order to reveal the dynamic characteristics of the pressure vessels, and to establish the quantitative relations between the concerned parameters, a series of studies have been made experimentally, theoretically and numerical simulation in present paper. The important results are summarized in the following several aspects.First, the vessels with 10°, 15°and 20°winding angle , respectively, and the monobloc cylindrical vessel are investigated experimentally. The experimental results show that the pressure vessels with flat-wound ribbons have residual deformation subjected to inner central blast loading when the quantity of explosive is more than 100g TNT. And the deformations are mainly concentrated near the center section of blasting. The vessel with 10°winding angle ruptures under 500g TNT. The vessel with 20°winding angle ruptures under 450g TNT, and the rupture locations of two vessels are near the central section of explosion. In the same time, the few broken fragments are produced. The ribbons are subjected to tensile stress in the length direction and compressive stress in the width direction. And the values of stress decrease gradually from the center of the vessels to the cover and flange. Experiment shows that the vessels subject to larger TNT explosion impact loading with the decreasing of the winding angle of the ribbons. The ribbon vessels compared with the monobloc vessels have better capacity of the plastic deformation, absorbing and releasing energy. In addition, both sizes of rupture and harm to environment are less than those of the monobloc.Secondly, based on the experimental results, the dynamic responses of the pressure vessels with flat-wound steel ribbons are studied through using rigid-plastic theory. The models of the plastic deformation of the vessels subjected to internal rectangular loading and triangular loading are given, respectively. The formulas of static limit loading, residual deformations and time of dynamic responses of the vessels are obtained. The limit loading of the vessels subjected to rectangular loading is smaller than that of the monobloc cylindrical vessel under the same conditions. The better the ribbon vessel capacity subjected to limit loading is, the more layers of the ribbons is. The deformation models of the vessels subjected to triangular loading are basically consistent with the ones that are obtained by the experiments. The residual deformations are concentrated on close center section of the vessels. The inner shell and the ribbons of the vessels are separated under the larger rectangular loading. The more the distance of the ribbons away from the inner shell is, the larger the residual deformations of them are. The theoretical values of the residual deformations of the ribbons are larger than the experimental ones because the pre-stresses of steel ribbons, the frictional force between the layers and the strain rate effect of the material are ignored possibly. The residual deformations of the vessels increase gradually with the winding angle increasing. The smaller the winding angle of the ribbons is, the higher the capacity of the deformation resistance of the vessel is.Finally, based on elastic-plastic theory, numerical simulation is achieved by non-linear finite element code LS-DYNA. The sizes and material parameters of FEM of vessels are identical to those of the experimental vessels. The strain rate effect of the materials is considered using Cowper-Symonds model. The numerical results show that the vessels have residual deformation when the quantity of explosive is larger than 100g TNT subjected to inner center explosion loading. The maximum deformation is on the centre cross section of explosion. The results simulated are consistent with those obtained by the experiment. The residual deformations of the ribbons is larger than those of the inner shell, and the larger the distance from the ribbon to the inner shell is, the larger the residual deformations of the ribbons are. The results are identical to the theoretical. The frictional forces between the ribbon layers improve the capacity of the deformation resistance remarkably. Therefore, the residual deformations of the ribbons theoretically are larger than those numerically. The vessel with smaller winding angle has the higher deformation resistance capacity. The residual deformations of the vessels are larger than those of the monobloc cylindrical vessels subjected to more than 100g TNT, it is caused by tensile strength of the materials made up the ribbons is smaller than that of the monobloc materials, and two kinds of vessels have different principle of absorbing and releasing energy.It is the first time that the study on dynamic characteristics of the pressure vessels with flat-wound steel ribbons in this paper is performed in the field. The work are extremely worthy for explosion resistance design and engineering application on the pressure vessels with flat-wound ribbons.