Method Of Open Performance Analysis And Structure Optimization For Soft PSD In Dual-Pulse Solid Rocket Motor

Double-pulse solid rocket motors have been more and more widely used in rocket weapons because of their advantages such as dual-range attack capability,large kill area,good maneuverability and large inescapable area.Ensuring the effective isolation and reliable opening of the pulse isolation device is one of the key issues in the development of the doublepulse solid rocket motor.In this paper,the mechanical properties of the compartmentalized double-pulse motor compartment are studied in depth and systematically against the background of the compartmentalized double-pulse motor,which provides an important reference for the design of the pulse isolation device and the engineering development of the double-pulse motor.The main work of this paper is as follows:(1)The mechanical properties tests of the EPDM(Ethylene Propylene Diene Monomer)spacer of the double-pulse motor were carried out at different temperatures,including uniaxial isometric tensile tests and equal biaxial isometric tensile tests.(1)The mechanical properties of the dual-pulse motor EPDM spacer were tested at different temperatures,including uniaxial isometric tensile tests and biaxial isometric tensile tests.The fracture morphology of the specimen under uniaxial tensile conditions was analyzed,and it was found that there were two types of fractures: rough slow expansion zone and smooth fast expansion zone,which belonged to high elasticity fracture in ductile fracture;the effects of loading rate and temperature on the stress response and fracture elongation in uniaxial isometric tensile tests were analyzed.The higher the temperature,the lower the stress at the same strain,and the lower the elongation at fracture,and the effect of temperature on elongation at fracture is greater than the effect of strain rate on elongation at fracture;the limitations of the two common biaxial tensile test principles are analyzed,and it is pointed out that the first test method is difficult to obtain the elongation at fracture and the second test method is difficult to obtain the elongation at fracture at a given rate.(2)On the basis of the generalized standard model of vérité,a viscous superelastic intrinsic model with finite deformation was established from the perspective of thermodynamics,combined with the Johnson-Cook model to characterize the softening effect of temperature on the EPDM spacer,and finally a thermal viscous superelastic intrinsic model suitable for engineering applications was established;and uniaxial isotropic tensile and isobiaxial isotropic tensile test data at different temperatures and reference temperatures were used to As an application of the thermo-viscous superelastic model,a quantitative analysis of the "film swelling" method in the isobiaxial tensile test method was carried out by establishing a rubber film swelling model,and the curves of five constant strain rate deformations were calculated.It is proved that the "film swelling" method is difficult to precisely control the filling rate to meet the conditions of constant loading rate under a given loading rate.(3)The updated Cauchy stresses and consistent tangential stiffness matrix of the superelastic model were obtained by the analytical method,and the updated Cauchy stresses and consistent tangential stiffness matrix of the hot viscous superelastic model were obtained on this basis.The calculation method of the consistent tangential modulus of the hot viscous superelastic model using the complex step method is proposed.The numerical method has the same computational accuracy as the analytical method for suitable regression parameters,and the advantages of simplicity and modularity of the numerical approximation method are highlighted in the numerical development of very complex intrinsic models.(4)The Hencky strain tensor for finite deformation conditions is introduced,the principal true strain space is established,and the failure criterion based on the Hencky strain considering the temperature effect is established by analyzing the uniaxial tensile elongation at different temperatures and loading rates,ignoring the assumption that the strain rate affects the fracture elongation at larger times.A method to estimate the fracture elongation at a given loading rate from an energy point of view is introduced,and the failure criterion is calibrated using the fracture elongation under uniaxial and isobiaxial tensile conditions to obtain the model parameters.The failure criterion was developed using the secondary development subroutine UVARM provided by ABAQUS,and the developed secondary development subroutine UVARM was verified by finite element simulation of uniaxial tensile test.(5)Simulation analysis was conducted on the effects of five factors,including prefabricated defect distribution,prefabricated defect width,prefabricated defect depth,number of prefabricated defect strips and temperature,on the compartment opening performance of the axial type compartment.It was found that: prefabricated defects on the I pulse side are more conducive to the smooth opening of the compartment during II pulse work;the width of prefabricated defects has little effect on the compartment opening performance,and too large a width will cause the prefabricated defect The depth of prefabricated defects has a significant impact on the opening performance of the compartment prefabricated defects,the greater the depth of prefabricated defects,the shorter the opening time of the compartment prefabricated defects,the deeper the prefabricated defects,the insulation performance of the compartment will be reduced;temperature has a significant impact on the opening time of the compartment prefabricated defects,the higher the temperature,the shorter the opening time of the compartment prefabricated defects,too high a temperature may The effect of prefabricated defect depth and temperature on the opening time and opening pressure of two prefabricated defect schemes was studied,and a database of the opening time of two prefabricated defect schemes was established regarding the two factors of prefabricated defect depth and compartment temperature.The BP neural network model of prefabricated defect opening time with respect to prefabricated defect depth and compartment temperature was established by training the BP neural network with the established database,and the preliminary design of axial compartmentalized double-pulse motor compartment under given conditions was carried out by using the trained BP neural network model,which laid the foundation for further design later.The results show that the developed intrinsic structure model and failure criterion can better describe the mechanical properties of the EPDM rubber spacer,and the BP neural network model established on this basis can be effectively used for the preliminary design of the soft spacer of the axial spacer type double-pulse motor.