Study On The Damage Effect Of Internal Explosive Quasi-Static Pressure Loads To Bulkhead Structures

Due to semi-armor-piercing anti-ship missiles carry a large amount of explosives and can penetrate the bulkheads and explode inside ships,they can be deadly to surface ships.Semi-armor-piercing anti-ship missiles can cause extensive damage inside ships.The main loads of semi-armor-piercing anti-ship missile include shock wave,fragments and quasi-static pressure.The shock wave is characterized by its high peak and short duration,mainly result in damage to the cabin bulkhead where the explosio n occurred.After the shock wave,the gas pressure in the cabin increases due to the post-combustion effect of the explosion products and forming the quasi-static pressure of high temperature and high pressure.Although the peak value of quasi-static pressure is low,its long duration and large cumulative impulse lead to the damage to the bulkhead of adjacent cabins and expand the scope of ship damage.It reveals that the quasi-static pressure is the important load that causes the damage of the ship in a wide range.In order to study the damage effect of internal explosion quasi-static pressure on the bulkhead,theoretical analysis,the model test and the simulation calculation are adopted to study the damage effect of the bulkhead structure and the characteristics of quasi-static pressure load.Studying the damage effect of implosion quasi-static pressure load on the bulkhead structure is helpful to accurately evaluate the damage efficiency of semi-armored anti-ship missile.(1)In order to study the internal explosive load characteristics of the cabin,the shock wave aggregation mechanism at the corners of the cabin structure with different aspect ratios was studied by means of simulation calculation and theoretical analysis and the functional relationship between the high pressure range and the aspect ratio was fitted to realize the calculation of the high pressure range of the cabin corner.By using NMQ method,considering explosive detonation products and combining ideal gas state equation and BKW state equation,the quasi-static pressure peak of implosion is theoretically analyzed.The reliability of the theoretical formula is verified by 6 times of quasi-static pressure measurement tests.The formula for calculating quasi-static pressure peak value is presented,which can accurately calculate quasi-static pressure peak value.(2)In order to study the quasi-static pressure load characteristics of adjacent tanks.The clapboard with holes is clamped between the two cabins to construct the adjacent cabin environment.The opening area of the diaphragm with holes accounts for 3%,5%,10%,15% and 20% of the diaphragm area respectively.The quasi-static pressure of the adjacent compartment was measured and the finite element simulation was carried out for the test conditions.The method of quasi-static pressure rise time for adjacent tanks is further deduced.Using this formula can predict the rising time of quasi-static pressure for the adjacent compartment under enclosed explosion.(3)In order to evaluate the performance of the bulkhead structure against quasi-static pressure,a simplified model of quasi-static pressure curve was proposed based on the above research results of quasi-static pressure characteristics of internal detonat ion.Based on this model,a test device was designed to evaluate the performance of the bulkhead structure against quasi-static pressure of implosion.Two key technologies involved in the test process are studied in detail: the method of artificial film breaking and the calculation of pressure relief time.The artificial explosive film breaking test was carried out and the pressure relief time was analyzed theoretically.The designed quasi-static pressure generator can be used to evaluate the performance of the bulkhead structure against quasi-static pressure.(4)In order to study the dynamic response process of the bulkhead structure under quasi-static pressure load,the designed quasi-static pressure generator was adopted,and the simulation model was established based on AUTODYN 3D finite element simulation software.The deformation process of the bulkhead structure under quasi-static pressure load was studied.The model test of cabin explosion was carried out,and the influence of explosion distance on the deformation deflection of bulkhead was studied by changing the stand-off distance.The research shows that the deflection increases with the increase of the explosion distance,which is not consistent with the conclusion of the air explosion.Based on the deformation mode of the bulkhead obtained by test,the theoretical calculation method of the bulkhead deformation deflection under quasi-static pressure is established by using the modal approximation method,and the accuracy of the calculation method is verified by comparing with the experimental and simulation results.Finally,based on the finite element simulation calculation,the influence law of quasi-static pressure rise time and quasi-static pressure peak value on the bulkhead deformation deflection is studied with the bulkhead deformation deflection as the damage degree index.(5)In order to study the failure mode of bulkhead structure under quasi-static pressure load,the failure modes of the adjacent bulkheads were obtained by carrying out interna l explosion tests with different explosive equivalents.The failure process of bulkhead structure under different failure modes is analyzed through the simulation calculation.Consider quasi static pressure rise time and peak pressure effect on the failure mode,based on dimensional analysis to the bulkhead failure mode on the number of dimensionless damage is analyzed.Based on a large number of simulation results,the relationship diagram of the bulkhead failure mode with the damage number is drawn,and w hen the quasi-static pressure rise time and pressure peak are known,the rapid prediction of bulkhead failure mode can be realized.