Analysis Of The Influence Of Different Rifling Section Shape On Dynamic Stress In The Process Of Warhead Extrusion

During the squeezing process of the warhead,due to the effects of gunpowder gas pressure,steering side force,squeezing resistance and high temperature,and the difference in friction characteristics between the gun and the bullet,the warhead is prone to deformation and damage.Different,will lead to the difference of dynamic stress changes in the warhead squeezing,so indepth analysis of the warhead squeezing force changes under different barrel cross-sectional shapes is of great significance for improving the design of the warhead.This paper takes warheads with different barrel rifling cross-sectional shapes as the research object.Through theoretical analysis,numerical simulation,and experimental verification,the dynamic stress changes during warhead squeezing under different barrel rifling cross-sectional shapes are analyzed,and the differences are revealed.The relationship between the cross-sectional shape of the rifle and the squeezing of the warhead.It provides certain data support and theoretical basis for further research on gun / projectile matching design.The main research contents of this article are as follows:(1)According to the classic internal trajectory theory,considering the influence of different cross-sectional shapes on the internal trajectory pressure,establish a modified internal trajectory model,use the fourth-order Runge-Kutta method,compile the internal trajectory calculation program,and obtain different cross sections of the barrel.The pressure-time curve under the shape.According to the pressure of the gunpowder gas under different rifling crosssectional shapes of the barrel,analyze the lateral force and the squeezing resistance of the movement in the warhead,and compare the quasi-static squeezing resistance with the test to verify the quasi-static squeezing resistance calculation formula Correctness.(2)Study the heat conduction theory of the gun / projectile material,establish a theoretical model of the transient heat conduction of the gun barrel,based on the finite difference method,use MATLAB software to compile the calculation program,calculate the temperature distribution of the barrel,and select the 50 mm cross section from the rifle According to the internal ballistic equation,the basic thermal coefficient(temperature of gunpowder gas,convection heat transfer coefficient)of gunpowder gas burning in the bore is calculated as the initial condition in the simulation calculation process.And the internal and external boundary conditions,and based on the thermal conductivity parameters of the barrel material(linear expansion coefficient,thermal conductivity,specific heat,etc.)and mechanical performance parameters(such as elastic modulus,Poisson's ratio,etc.),established by TG and Abaqus finite element simulation software The transient heat conduction finite element model of the barrel is used to analyze the heat conduction process of the barrel,and finally compared with the barrel temperature field obtained by the finite difference method.(3)Based on the shear slip friction theory,the friction characteristics between the warhead and the barrel are analyzed.The shear slip friction model of the gun / projectile contact interface and the friction model with variable friction coefficient are obtained.The friction temperature rise,plastic deformation temperature rise and the heat transfer of the projectile in the process of warhead extrusion and movement in the barrel are analyzed theoretically.Taking the barrel temperature in(2)as the temperature field of the next warhead launch,the vuamp bore pressure subroutine,the shear slip vfric friction subroutine and the temperature dependent variable friction coefficient friction subroutine are written in FORTRAN language,and they are jointly solved with ABAQUS / explicit dynamics,and the bore pressure value obtained is compared with the test value to verify the correctness of the model Under the action of thermal force coupling,the law of temperature rise of warhead with different friction models is analyzed.(4)According to the characteristics of the barrel structure,the NX UG is developed for the second time,and the expression parameter suppression method is used to establish the parametric template of the barrel.By entering the barrel structure size parameters,the trapezoid,multi-arc and polygon arcs are quickly established The rifled barrel model,based on(3),is coupled with the internal ballistic pressure subroutine and friction subroutine to establish a thermal-mechanical-friction coupling warhead squeezed into a finite element simulation model for different rifling cross-sectional shapes.Simulation calculation of warhead squeezing,analysis of the influence of rifling cross-section shape on warhead squeezing stress and strain and squeezing resistance.In this paper,through the research on the force of warhead extrusion in different rifle crosssection shape of gun barrel,it is found that in the process of warhead extrusion in the same rifle cross-section shape,the stress and strain on the guide side of the warhead are higher than those in the groove and higher than those in the non groove,and the area on both sides of the notch is the stress concentration area;the guide side,groove and non groove of the warhead under the four rifling cross-section shapes are the stress concentration area The change trend of the stress at the groove is the same,and the stress value under the rectangular rifling is the largest.The results show that the thrust resistance of the warhead in four kinds of rifling cross-section is increasing at first and decreasing.The thrust resistance of the warhead in rectangle rifling is the highest,followed by trapezoid,multi arc and multi arc are almost equal.