Numerical Simulation Of A New Type Of Indoor Layered Composite Protective Structure

The Hydraulic burst test is a standard test for testing the ultimate bearing capacity of pressure-bearing equipment.In this test,the pressure-bearing equipment was leaked or broken by the method of water injection and pressure.However,during the hydraulic burst test,splashed metal fragments can impact and damage the closed laboratory wall and the fragile device placed above the laboratory.In order to solve the problem of damage to the closed laboratory caused by high-speed debris generated during the test,in this paper,the assembled rubber/steel double-layer composite structure is proposed,and its impact resistance and protective effect are simulated by professional explicit nonlinear finite element software LS-DYNA.The main tasks are as follows:(1)For the different thickness of the protective structure,the simulation results after the repeated impact of the fragments were compared.According to the damage results of the steel plate and the rubber layer,the thickness of the steel plate and the rubber layer were determined to be 8mm and 15mm,respectively.Then the simulation that the debris impact steel-concrete wall is carried out.According to the simulation results of the internal and back cracks of the concrete wall,the gap should be left between the protective structure and the wall.(2)Considering the influence of aspect ratio,target angle,incident speed and incident angle on the impact history of debris,the simulation of the three shapes of cone,ellipsoid and sphere is carried out.The results show that:①For the cone fragments,according to the difference of the residual speed in the vertical direction under different working conditions,there are two types of typical working conditions—incident speed at 0≤v<80m/s and 80≤v<300m/s;For ellipsoidal fragments,there are three typical types of conditions—incident speeds at 0≤v<80m/s,80≤v<150m/s,and 150≤v<300m/s;for sphere fragments,there are three typical conditions——incident speed at 0≤v<80m/s,80≤v<120m/s and 120≤v<300m/s.②Other conditions are unchanged,the residual velocity in the vertical direction decreases with the increase of the aspect ratio;the residual velocity in the vertical direction decreases with the increase of the target angle;for fragments of the same mass,the residual velocity of the cone fragments in the vertical direction is less than the residual velocity of the ellipsoid fragments and sphere fragments.(3)The damage and protective effects that spherical debris impact the tiled rubber/steel composite structure under different working conditions were simulated and compared with the protective structure of pure steel plate.The results show that:①The residual speed of the debris after impacting the rubber/steel composite plate is much smaller than the residual speed after impacting the pure steel plate.②When the incident angle is constant,the damage value of the steel plate increases with the increase of the incident velocity;when the incident velocity is constant,the damage value of the steel plate decreases with the increase of the incident angle.③Depending on the initial operating conditions,the debris will rebound downwards or be embedded in the rubber layer after the secondary impact tiled rubber/steel composite structure,indicating that the debris will not rebound and hit the vulnerable device above the laboratory.(4)In order to improve the protective effect of the tiled rubber/steel composite structure,two improved structural forms that the inclined and serrated rubber/steel composite structure are proposed.These three rubber/steel composite structure were compared and analyzed from five aspects:residual speed,rebound angle,energy curve,pit depth of the steel and secondary impact protection.The results show that:For the case of debris at the speed of v<80m/s,the serrated rubber/steel composite structure is preferred;for the case of 80≤v≤120m/s,these three protective structures have the same protective effect;for the case of v>120m/s,the inclined rubber/steel composite structure is suitable.In summary,the assembled rubber/steel composite structure proposed in this paper can not only protect the walls around the laboratory,but also change the pre-ejection direction after the secondary impact of debris so as to effectively protect the vulnerable device above the laboratory.Moreover,the protection structure is characterized by simple structure,low cost and easy installation and replacement,which can be widely used in the field of civil protection.