Research On Performance And Structure Of Stainless Steel Diaphragm For High Temperature And High Pressure Gas Shock Tube

Shock tube is a common research platform of explosion mechanics,which is widely used in shock wave and hypersonic flow field.Compared with conventional shock tube,high temperature and high pressure gas shock tube has the characteristics of high driving gas temperature and high pressure,requiring controllable blasting performance for diaphragm at high temperature.The blasting performance of the diaphragm has a significant effect on the properties of the shock wave generated by the shock tube.Hence,it is of great significance to investigate the blasting performance of the diaphragm for the application of shock tube.For large-caliber shock tubes,it is difficult to process the arch type diaphragm.On the contrary,the flat type diaphragm is an ideal structure.Based on the research on the microstructure and high temperature performance of 316L stainless steel material and the finite element simulation method,the simulation and blasting test on a large diameter plate groove type diaphragm of high temperature and high pressure gas shock pipe was carried out in this paper.The variation of the blasting performance of the diaphragm and the corresponding blasting were carried out.The main results were as the following:(1)The microstructure and mechanical properties of 316L stainless steel plate at different temperatures were analyzed.The results show that the distribution of microstructure of the plate is not uniform,with complementary streamline along the rolling direction.The austenite texture exists in plate,with different strength of the texture at different locations also.In the range of room temperature to 500?,the mechanical properties of materials decrease with the increase of temperature,and decrease slowly at 300 to 500?.The change of tensile strength of 316L with temperature leads to the decrease of bursting pressure at high temperature.(2)Four kinds of diaphragm models,crossing arc,crossing straight,six straight and eight straight grooves were established,and the blasting process was simulated by using LS-DYNA software.The results show that the blasting pressure of the cross arc grooving is the highest with the best shape when the unanimous thickness and the unanimous depth of grooving are set for four diaphragm models.(3)The models of crossing arc-slotted diaphragm with different groove depths,thicknesses,diameters and clamps were investigated,respectively.The results show that the burst pressure of the diaphragm is proportional to its remaining depth when the ratio of the remaining depth to the thickness of the diaphragm is in the range of 0.3?0.8.When the residual thickness is constant,the burst pressure decreases slightly with the increase of the thickness.The relationship between bursting pressure and the reciprocal of discharge caliber is the linear one.According to the simulation,the prediction formulas of burst pressure of the diaphragm are fitted with different geometric parameters as following,(?).The error between the two results is less than 8%,which can express reasonably the relationship between the diaphragm structure and the burst pressure.(4)The anisotropy model of tensile strength based on texture at the grooving site on diaphragm was established to simulate the possible diaphragm morphology under pressure.It shows that the difference of tensile strength between the two grooves leads to the inhomogeneous fracture morphology,which indicates that the influence of anisotropy on the burst morphology of the diaphragm cannot be ignored.(5)The burst pressure of the diaphragm in the range of room temperature to 450? was analysed.The results show that the burst pressure of the diaphragm decreases with the rise of temperature.The finite element simulation of the diaphragm with different geometrical parameters was carried out to fit the relationship between the burst pressure and temperature.Combining with the fitting relationship in(3),the burst pressure of the diaphragm with different geometrical parameters at different temperatures can be predicted effectively.(6)The blasting test of 316L stainless steel diaphragm with diameter of 100mm and different thickness was operated in a high temperature and high pressure gas shock tube.The results show that the error between the burst pressure of the diaphragm and the finite element simulation results is less than 6%.The blasting morphology of diaphragm is better consistent with the simulation results.