The Study Of Interaction Issue Of Bullet And Sniper Rifle

As a high precision shooting weapon,to continuously improve the firing accuracy of sniper rifle is the main target.The initial disturbance is the result of interaction between bullet and barrel and the main cause of firing accuracy,which is closely relate with parameter design of bullet and barrel.However,current way of design cannot be used for further study.As a result,deeper researches regarding the principle of interaction between bullet and barrel are needed.Meanwhile,attentions should been paid to tiny aspects which are easy to be ignored during regular design.In this case,the influence of how barrel and bullet affect initial disturbance can be comprehensively analyzed.The paper is to study the parameter matching between bullet and barrel,which is treated as the theoretical base of high precision sniper rifle designing.Combining experimental data and numerical calculation,numerical calculation model is built in this paper,which is based on nonlinearity finite element theory.More concern is paid to how the structure parameter of barrel and bullet affects the launching process of bullet.By applying robust design concept into bullet-barrel parameter matching design,a workable method of sniper rifle’s parameter matching design is developed.More details is as below:In this paper,a certain type sniper rifle is choosen as the study object,many performance tests are carried out against it.Include bore pressure test,initial velocity test,quasi-static engraving test and the muzzle vibration test.By using copper crush gauge method and photoelectrical way,the maximum pressure and initial velocity data of sniper rifle are gained.In order to know how forcing cone structure influences the resistance of bullet when engraving,two different quasi-static engraving tests under different forcing cone angle were conducted.A new auxiliary engraving test apparatus was designed for the test.The material testing machine pushes the bullet engraving into the forcing cone and meanwhile takes the records.The high-speed camera took picture of bullet after it left the barrel and gained the vibration displacement in vertical direction.An auxiliary clamping device is designed to fix the barrel.The vibration displacement data within 500ms after bullet left barrel have been gained.Performance test is the most direct and efficient way to know the performance of sniper rifle,meanwhile it is the precondition and verification of carrying out relevant theoretical research.Based on the non-linear finite element method,a model is built to calculate the interaction between bullet and barrel.In the model,the bore pressure calculation program of internal ballistic and bullet launching numerical calculation program are coupled.The barrel pre-bent condition which is caused by gravity and the engraving process of bullet have already been fully considered.By ensuring the integrity of internal ballistic,the accuracy of numerical calculation model of interaction between bullet and barrel have been further improved.Based on the numerical calculation model,it is also analyzed whether gravity will have influence to the muzzle vibration and bullet movement in the bore.The calculation result of chamber pressure and initial velocity and muzzle vibration is very close to experiment data,which shows that the numerical calculation model of interaction between bullet and barrel is correct.By establishing numerical calculation model of quasi static engraving and dynamic engraving,the changes of engraving resistance,stress and strain have been gained during quasi static and dynamic engraving process,the composition and proportion of engraving resistance also have been analyzed.Engraving resistance is comprised of two parts:the axial positive pressure and the axial frictional force.Of which the axial frictional force is the major components,while the axial positive pressure will disappear after engraved into the forcing cone.The structure of forcing cone has different influences to engraving resistance when the engraving is in dynamic condition and in the static state.The paper mainly analyzed the distribution of strain/stress of bullet shell,bullet core and barrel in axis direction,circumferential direction and radial direction,then found the distribution and size of strain/stress in two different states are obviously different.The influence of structure parameters which is changed in a small range of forcing cone,rifling and configuration of sniper barrel on launching process was calculated by numerical calculation model of bullet-barrel interaction.The swing angle of bullet is taken as the main eigenvalue to discriminate the quality of parameter,so as to measure the relationships between parameter and warhead swing situation,then carry out related analysis work in quantitative and qualitative.The influence of parameter of forcing cone,rifling and configuration were obtained from calculation result.The effect of structure parameters,mass error and eccentricity of bullet and the major controlling parameter of powder on launching process was calculated by numerical calculation model of interaction between bullet and barrel,and the single factor analysis method was used in this analysis.The analysis result shows that,the longer of cylinder length,or the smaller of the amounts of interference,the less swing angle it will be.The mass error has great effects on initial velocity and maximum bore pressure while almost have no influence towards bullet swing.The effect of mass eccentricity on swing angle is greater than other factors,the greater eccentricity is,the more violent it swinging.The effect of major control parameter of powder on initial velocity and swing work by change maximum bore pressure,as the maximum bore pressure range 270MPa to 300MPa,the intensity of swing get the minimum value.Totally 12 groups of orthogonal simulation experiments were carried out for ten structural parameters,the mass eccentricity of bullet is noise factor and the swinging angle of bullet is the performance measurement.This is the application of robust design thought on study of matching design method of bullet-barrel parameter.According to the analysis of orthogonal experiment result,it’s effective to reduce swing angle of bullet in internal ballistic period by combining the optimal parameter obtained from result of single factor analysis.The two parameter group’s average and range of swing angle of bullet were calculated in two conditions,with and without noise.The results of simulation experiment are consistent with the robust analysis result,which indicate that the application of robust design thought on matching design of bullet-barrel parameter is feasible.