Numerical Simulation Analysis Of The Penetration Characteristics Of Storage Tanks Impacted By Explosive Fragments

In chemical parks,storage tanks generally store a large amount of flammable and explosive media.If overpressure or a fire occurs,it is very easy to cause an explosion.The fragments from the explosion will impact other storage tanks in the tank area.Once the fragments causes the tank wall to penetrate,the leakage of the liquid stored in the tank will cause a secondary explosion,which will trigger a domino accident,and the consequences will be unimaginable.Therefore,a numerical simulation study on the penetration behavior of the storage tank under the impact of explosive fragments is carried out to reveal the penetration characteristics of the storage tank and the failure process of the storage tank under different fragment impact conditions,and provide for the failure and risk assessment of the storage tank in the chemical park theoretical basis.The main research contents and conclusions of this paper are as follows:(1)Aiming at the local deformation characteristics of the penetration behavior of the fragments impacting the storage tank,the smooth particle hydrodynamics and the finite element method(SPH-FEM)are used to construct the storage tank to be limited under the impact of three small fragments of cube,sphere and cone Metaanalysis model,numerical simulation study of the penetration behavior of fragments hitting the storage tank.The result shows that:compared with the conventional FEM method,the SPH-FEM coupling analysis model has the obvious characteristics of accurate local deformation description and high calculation efficiency,and is more suitable for the numerical simulation of the penetration behavior of fragments impacting the storage tank.(2)The SPH-FEM coupling analysis model was used to numerically simulate the penetration behavior of a 200 m3 vertical vaulted storage tank from impact deformation to penetration by small fragments.The three types of fragment shape,fragment impact velocity,and fragment impact angle were studied.The law of influence of various factors on penetration characteristics.The result shows that:For a cube fragment with a mass of 62 kg,the minimum impact velocity at which the fragment penetrates the tank wall under a normal impact condition is 97 m·s-1.When the fragments penetrates the structure of the storage tank,from the significant local plastic deformation of the fragments hitting the tank wall to the formation of curling when it penetrates the tank wall,the impact penetration process is manifested in four typical stages of extrusion,hole breaking,penetration and inertial flight.The final perforation shape is closely related to the largest projection surface of the fragments on the storage tank.The cube fragments have the strongest hole reaming ability and the strongest damage ability to the storage tank.The penetration process of small fragments hitting the storage tank is a typical localized damage under the perforation behavior.The greater the fragment impact speed,the larger the diameter and curling of the perforation,the greater the penetration energy required,about 10%of the initial kinetic energy of the fragments Deformation energy converted into fragments,kinetic energy and deformation energy of storage tanks.The radial diameter increases with the horizontal impact angle and wall thickness,and the axial diameter increases with the vertical impact angle and wall thickness.The larger the wall thickness,the more obvious the perforation diameter changes.The greater the impact angle and wall thickness of the fragments,the greater the penetration energy required.(3)In order to further study the impact deformation process and penetration characteristics of large fragments on the storage tank equipment,three typical explosive fragments of long end cap fragments,hemispheric fragments and flat fragments and a 20000 m3 vertical vaulted storage tank were selected to construct a large finite element analysis model of fragments impact on vertical vaulted storage tank.Numerical simulation of the penetration behavior of fragments impacting the storage tank was carried out,and the dynamic response characteristics.The dynamic response characteristics of the fragments impacting the tank penetration process and the influence of related factors(including fragments type,fragments mass,fragments impact velocity,fragments impact angle and fragments rotation speed)on the penetration characteristics are studied.The result shows that:For a typical long-end cap type fragment with a mass of 6050 kg,under the condition of a positive impact,the minimum impact velocity at which the fragment penetrates the tank wall is 72 m·s-1.When the fragments are not enough to penetrate the tank wall,a wide range of plastic deformation will occur at the impact site of the storage tank,forming a concave triangular deformation area,showing four plastic hinge lines.According to the different impact speed and quality of the fragments,the failure modes of the fragments penetrating the storage tank are shown as partial failure,overall failure and rupture failure.The shape and size of the perforation after the fragments hit the storage tank vary with the types of fragments.Among them,the hemispherical fragments have the largest perforation size,and the long-end cap fragments require the most penetration energy and have the strongest damage to the storage tank.The greater the mass of the fragments,the greater the penetration energy required,the greater the maximum residual displacement of the storage tank,and the more severe the damage to the storage tank.The greater the fragments impact speed,the greater the penetration energy required,the greater the maximum residual displacement of the storage tank,and the more severe the damage to the storage tank.The larger the horizontal and vertical impact angles of the fragments,the greater the penetration energy required,and the greater the maximum residual displacement of the storage tank,and the more serious the damage to the storage tank.However,after the impact angle reaches 45°,the fragments is parallel to the wall,excessive velocity component causes sliding with the tank wall and weakens the damage to the storage tank.The higher the speed of the fragments,the smaller the required penetration energy and the smaller the maximum residual displacement of the storage tank.Because the speed of the fragments changes the penetration mode,the ability of the storage tank structure to resist penetration is weakened,and the fragments is easier to penetrate the storage tank.