点火过程是内弹道的初始阶段,但由于点火过程的复杂性以及点火机理仍然不完善,点火过程始终不能与内弹道有机结合,使得目前工程上的内弹道计算只能忽略点火过程而直接选择点火压强作为计算初始点。以零维内弹道理论为基础,建立了点火过程3个阶段,即点火诱导期、火焰传播期和充气期的简化理论模型,可以与零维内弹道有机结合,从而完成了内弹道从环境压强(而不是点火压强)开始计算的完整过程。通过实例计算与验证,该模型能够很好展示在点火阶段燃烧室压强的建立过程,并可以计算得到点火延迟时间、火焰传播时间、点火药流量等点火参数,具有较高的预示精度,满足工程计算要求。研究表明,建立的点火过程理论模型与传统零维内弹道一样计算简便快捷,并具有较好精度的工程应用化特点。研究结果对于完善固体火箭发动机内弹道理论、提高固体火箭发动机内弹道预示精度,均具有重要的实际应用意义。由于采用了简化的点火过程理论模型,该结果不能直接用于点火性能的研究,只能用于零维内弹道性能的预估与计算。

Ballistics is one of the foundational disciplines in weapons science and technology,closely related to the development of weapons technology. With the rise and development of intelligent projectiles and rockets,the theory and technology of intelligent ballistics will be a major direction for the future development of exterior ballistics. Nevertheless,how to understand the concept,connotation,and functions of intelligent ballistics,as well as its differences from existing projectiles and rockets in terms of flight trajectories,the key technologies it relies on,the challenges involved,and the issues that should be considered for the subsequent development,are still under discussion. Based on the theory and technology of exterior ballistics and focusing on the future development of exterior ballistics,this article tends to analyze and organize the aforementioned issues with the aim of providing assistance for the future development of intelligent ballistics theory and technology. It should be noted that the development of intelligent ballistics theory and technology has introduced numerous new problems,concepts,terminologies and technologies for exterior ballistics,which require continuous exploration,refinement,and gradual perfection by researchers in the field of exterior ballistics through ongoing research. This article merely serves as a starting point,hoping to inspire more researchers in the field of exterior ballistics to engage in this area of study and gradually develop a theoretical framework.

According to the demand of axial cold launch,an axial cold ejection device using high-pressure nitrogen as ejection energy was designed to avoid the pollution of the internal space of the platform. The structure composition,working principle and main design points of the axial cold ejection system were introduced. By using the ideal gas equation of state,mass and energy conservation equation and aerodynamics,the mathematical models were established for the high-pressure chamber,low-pressure chamber,valve port gas flow,and missile motion of the axial cold ejection system. In order to improve the separation speed and reduce the overload peak,based on the established mathematical models and the internal ballistics structural-parameters,VB language was used to program. Through simulation calculation and analysis,the main structural parameters of the ejection system such as cylinder initial pressure,volume,initial volume of low-pressure chamber,electromagnetic valve orifice,natural frequency,damping ratio and piston diameter,were studied to determine the impact on missile separation speed and launch overload. The influence of various structural-parameters change on the missile separation parameters was found,and the mechanism of the influence laws was analyzed. This study provides a theoretical basis for the optimization of the structural parameters of ejection system,and provides a theoretical reference and basis for the internal ballistics design of the same type of axial cold ejection launcher.

To investigate the propagation characteristics of detonation waves influenced by lateral expansion with weakly constrained boundaries in a narrow straight channel,a two-dimensional numerical simulation was conducted using H₂/O₂/Ar mixture as the fuel and a detailed chemical reaction mechanism consisting of 48 steps. The study examined the effects of type of weakly constrained gas,temperature,and height of combustible premixed gas on the propagation speed and wave structure of the detonation wave. It is found that using argon or products of combustion as weakly constrained gases has no significant impact on the lateral expansion extent and wave structure of the detonation wave. When the temperature of the weakly constrained gas is 1 000 K,1 500 K,and 2 000 K,the shock wave propagating within the products of combustion exceeds the detonation wave speed,resulting in the generation of an induced shock wave pointing towards the detonation wave. This induced shock wave leads to an increase in the velocity of the detonation wave. Increasing the temperature of the weakly constrained gas from 300 K to 500 K has no effect on the propagation characteristics of the detonation wave. Higher heights of combustible premixed gas results in less loss of velocity for the detonation wave,and there exists a minimum combustible premixed gas height that prevents the detonation wave from extinguishing. When the temperature of the weakly constrained gas is 300 K,the dimensionless critical propagation size of the detonation wave h/λ>0.13. The findings of this study are of significant importance for understanding the mechanisms of lateral expansion losses in detonation waves.

From the development trend of modern artillery and ammunition technology,the problems faced by the internal ballistics of artillery were analyzed. The development direction of internal ballistics theory and technology is mainly reflected in three aspects. The first aspect is to improve the combat effectiveness of conventional solid propellant artillery. The second aspect is to develop internal ballistics theory and control technology that is matched with the launch methods of special ammunition such as guided munitions. The third aspect is to study the internal ballistic theory and control technology of new energy artillery. On this basis,combined with the research status at home and abroad,several key issues were reviewed,proposing research strategies.

In order to overcome the question of large fluctuation of trajectory tracking accuracy due to complex external unknown interference in the trajectory tracking control process of six-freedom-degree quad-rotor UAV,a new-type cascaded double-closed-loop control strategy was proposed for velocity error,and position and attitude error. Firstly,the model predictive control(MPC)was used to project the velocity closed-loop controller,and the sparrow search algorithm(SSA)was applied to the rolling optimization process of MPC to obtain the feasible solution due to the fast convergence and strong robustness. In order to solve the large computation in MPC,sliding mode control(SMC)was used to design the dynamic controller according to position and attitude respectively. SMC is insensitive to external interference,robust and does not need accurate modeling,thus solving the problems of external uncertain interference and difficulty in accurately modeling UAV. The saturation function was used to replace the symbolic function to make the input of the actual system continuous,thus effectively reducing the high-frequency chattering phenomenon in SMC. Finally,the stability of the SSA-MPC controller was proved by Lyapunov stability theory. By the proposed method,the six-freedom-degree quad-rotor UAV can achieve high-precision trajectory tracking control under complex external unknown interference and uncertain parameters,and the trajectory tracking accuracy is obviously better than the UAV control system composed of traditional single controller. The proposed controller is effective for the trajectory tracking control of quad-rotor UAV under complex external unknown interference.

The issue of abnormal high initial-pressure inside the launch tube in a small-scale ejector was discussed. A calculation method based on a zero-dimensional internal-ballistics model was proposed,considering the combustion heat-release reaction of the rich gas,and the method has the advantages of simple principles,small calculation amount and fast calculation speed. A calculation program was developed using the Matlab. The effectiveness and accuracy of the numerical model were validated by comparing with ejection test results. Based on the above research,the phenomena of secondary combustion in the launch tube were further studied. The study shows that the time-curves of the pressure of launch tube and the acceleration of missile exhibit obvious double-peak effects whether secondary combustion occurs or not. Additionally,the secondary-combustion effect not only significantly increases the peak value of the first peak but also leads to a decrease in the peak value of the second peak. Furthermore,a sharp drop of pressure in the launch tube to a low value occurs after the peak value of the first peak,and the secondary-combustion effect also significantly affects the ejection velocity and the missile ejection-time. Further research shows that by increasing the initial volume of the launch tube and reducing the rich gas content,the effect of secondary combustion on the low-pressure chamber pressure and missile acceleration can be reduced. This study provides theoretical support for the design of internal ballistics in ejector system,and has a certain degree of universality and reference value.

The inflation process of parachute is the most critical step during the landing of the Mars probe. The model of computational fluid dynamics(CFD)and structural dynamics was built,considering low atmospheric-density and supersonic flow. The flow field was solved by using compressible flow-field model,and the structural dynamics was analyzed by using multi-node mass damped spring model of parachute system. The flow-field of the parachute was calculated,and the pressure field of canopy surface for the previous time step was imported to the multi-node mass damped spring model of parachute system. The canopy shape of the next time step was obtained,and the parachute shape and the flow field were obtained during the opening process. The test results and calculation results were analyzed comparatively,and the parachute inflation process was simulated under this condition. The numerical results are well consistent with the experiential results,so the mathematical model used is reliable. The results show that there is obvious vibration after the parachute-opening dynamic-load reaches the peak value,and the vibration frequency is only related to its own characteristics; the speed of the canopy opening is slow at first and then fast; under the same initial-speed,the peak value of the parachute-opening dynamic-load increases with the increase of atmospheric density; under the same initial dynamic-pressure,the peak value of the parachute-opening dynamic-load decreases with the increase of atmospheric density.

To investigate the dynamic response characteristics of penetration warhead under impact load,the simulation of warhead penetrating into a semi-infinite concrete target was conducted using the projectile-target separation method. The dynamic response of the warhead under different charge and shell head-curve-ratios,velocities,and sizes was analyzed. The results indicate that the deceleration peak of charge is higher than that of warhead shell. The deceleration peaks and deformation of the charge are positively correlated with the head curve ratio of charge. The deformation of the charge caused by stress wave is primarily concentrated on its end face and at the transition between the head and cylinder section. Increasing the head curve ratio(CRH_S)of the warhead shell reduces deceleration peaks for both the shell and charge,as well as their maximum overload difference. Specifically,the maximum plastic strain of the charge at CRH_S=4 is about 29% of that at CRH_S=2,with a significant reduction in high strain area. The initial velocity of penetration mainly affects the overload amplitude. Furthermore,an increase in initial velocity results in higher overload and plastic deformation for both the shell and charge. Overload,penetration depth and stress amplitude adhere to similarity laws for different warhead-sizes,without considering factors such as concrete aggregate size and strain rate. However,larger warhead size results in more severe plastic-deformation of charge.

In order to study the influence of acoustic impedance difference on the flow field structure of detonation tube exit in jet environment,an axisymmetric model of the flow field inside and outside the detonation tube was established. The rhoReactingCentralFoam solver of the OpenFoam platform was used to couple the flow field inside and outside the detonation tube. Three free jet regions of argon,hydrogen and air mixture,and helium were constructed outside the tube. Combining with the simulation results of the static air outside the tube,the influence of the acoustic impedance difference of the medium inside and outside the tube on the detonation flow field structure was analyzed. The results show that the argon jet and the static air will form a reflected shock wave on the acoustic impedance discontinuity surface when the detonation wave overflows outside the tube. The helium jet forms a reflected rarefaction wave on the acoustic impedance discontinuity surface when the detonation wave overflows outside the tube. The hydrogen and air mixture jet has no effect on the process. The Mach disk formed in the argon jet and the static air is reduced to almost disappear. The slip line and the subsequent supersonic region encounter near the Mach disk. The Mach disks in the hydrogen-air mixture jet and the helium jet remain a certain size after decreasing. The slip line and the subsequent supersonic region encounter far away from the Mach disk. The acoustic impedance difference between the free jet and the explosive mixture causes the leading shock wave to deform and change its directivity. The curvature of the leading shock wave near the central axis in an argon jet decreases,and the leading shock wave in still air roughly presents a spherical wave shape. The leading shock wave in a hydrogen air mixture jet and a helium jet protrudes.

To study the mechanical response about rifling's steering side and band in engraving process,the motion,deformation of band and its mechanical mechanism during projectile engraving process were deduced based on the energy method,and the force relation between the rifling's steering side and band after engraving was analyzed according to the classical interior-ballistics theory,and the general expressions of the force on rifling's steering side during engraving process and after engraving were obtained. The influencing factors of the force on rifling's steering side were analyzed. Interior ballistics was simulated by using an elastic-plastic finite-element-method,and dynamic responses of the force on rifling's steering side were obtained under various operating conditions. The force on rifling's steering side,influence law of engraving velocity and angle of forcing cone were analyzed. The researches show that the force on rifling's steering side is positively correlated with engraving velocity and angle of forcing cone,and its trend of change is consistent with the bottom pressure of the projectile after engraving in. Within a certain range of velocity,the peak of the force on rifling's steering side during projectile engraving is much larger than that at the moment of maximum chamber-pressure,and the ratio of them shows a significant increasing trend as the engraving velocity increases. For the cased telescoped ammunition with longer free-travel-distance,the force is more complex in engraving process,so it's necessary to strengthen charge structure and optimize forcing cone to improve the barrel life. The calculation methods and conclusions mentioned can provide theoretical reference for projectile structure design and analysis of projectile-barrel matching.

In order to study the aerodynamic characteristics of the missiles with tail fins,simulation was conducted to study the unsteady flow-field of the missiles with rotating tail fins based on sliding mesh method. The numerical simulation method adopted in this paper was verified by the wind tunnel experimental results of army-navy finner(ANF)standard model. Taking a certain cross-shaped layout tail-fin missile as the research object,the variation laws and influencing mechanisms of various aerodynamic-characteristic-parameters at different Ma(Ma=0.9-2.0),attack angles(2 °,4 °),rotation speeds(π rad/s,2π rad/s,4π rad/s),and tail-fin inclination angles(0°,1°,2°),were analyzed. The calculation results show that the rotation speed has little effect on the longitudinal aerodynamic characteristics(drag,lift,pitch moment characteristics)of the missile,mainly affecting the roll characteristics and Magnus effect. The inclination angle of the tail fin has little effect on the lift characteristics parameters and pitch moment characteristics of the missile,mainly affecting the drag,roll characteristics and Magnus effect. The resistance characteristics parameters and lift characteristics parameters of the missile show periodic variation during missile rotating around its longitudinal axis(0°-360°),and the instantaneous coefficient of lift and drag is the smallest when the missile rotates to 45°. The body is the dominant factor in generating the resistance characteristic(about 85%). The contribution of the body and tail to the lift characteristics is basically about 50% each. Therefore,in the design process of the projectile and arrow,attention should be paid to the advantages and disadvantages of the fin cant angle and rotation speed,and a suitable oblique angle should be selected.

Cellular steel-tube-confined concrete(STCC)target has excellent anti-penetration ability and expandable performance. Based on finite analysis software ANSYS/LS-DYNA,the penetration process and anti-penetration mechanism of cellular STCC target normally penetrated by rigid projectiles were numerically simulated by using FEM/CSCM-SPH/HJC method. Compared with single-cell STCC targets and non-confined concrete target,the confinement effect of cellular steel-tube mainly reflects at the tunneling penetration stage and shows lateral confinement expansion of concrete at nose of projectiles. Compared with single-cell STCC target,surrounding cells of seven-cell cellular STCC target exert supporting on the steel tube in the impacted-cell. It restrains radial expansion of impacted concrete and bending deformation of steel tube,which can be treated as supplementary confinement of the surrounding cells. Compared with non-confined concrete target,it is the confinement of steel tube that improves the confining effect of concrete in the impacted cell,which enhances compressive strength and deformation performance of concrete in the impacted cell,and the penetration ability of the impacted cell is improved. Therefore,owing to confinement of the steel tube and supplementary confinement of the surrounding cells,the cellular STCC target exhibits excellent anti-penetration ability.

The penetration test of 12.7 mm armor-piercing incendiary ammunition on a certain type of ceramic composite armor plate structure was carried out. The limit penetration velocity of the projectile to the composite armor plate and the damage pattern of the target plate was obtained. The finite element model of the projectile penetration of ceramic composite armor plate was established based on the smoothed particle hydrodynamics method in LS-DYNA. The finite element model was verified by comparing the maximum penetration velocity of the projectile,damage patterns and perforation size on the front side of the ceramic plate,deformation and damage on the back side of the composite target plate obtained from the experiment and numerical simulation. Then,the effect of the attack angle on the dynamic response of the projectile and the target plate in the penetration process was simulated and analyzed. The results show that,the penetration ability of the projectile to the ceramic composite armor plate is enhanced due to the decreasing of contact area between the head of projectile and target when the attack angle increasing from 0° to 6°. With the attack angle further increasing,the penetration ability of the projectile penetration ability decreases. It is resulted from the interaction the tail of projectile with the unbroken ceramic outside the central crushing area of the ceramic plate after the projectile penetrates the ceramic target plate due to the large deflection angle of the projectile. The interaction consumes part of its kinetic energy and leads to the decrease of its penetration ability. The energy absorbed by the ceramic is approximately 5 times that of the composite material layer,indicating that the attack angle mainly affects the energy absorption of the ceramic plate and consequently influences the penetration of the target plate.

In order to study the lethal effect of small-caliber prefabricated fragmentation warheads in terminal defense,finite element method was used to simulate the detonation of prefabricated fragmentation warheads. The dispersion characteristics of fragmentation under four detonation conditions:central detonation at the bottom of the charge,single-point off-center detonation,dual-point symmetrical detonation,and dual-point center-off-center detonation was studied. The average final velocity and average scattering angle of the prefabricated fragments,as well as the distribution ratio,under the four detonation conditions were obtained. The research results show that when the detonation position is located at the contral-bottom of the charge,the scattered final velocity of 71.7% of prefabricated fragments is between 300-800 m/s. The scattered final velocity of the prefabricated fragments is approximately 687.1 m/s,and about 91.7% of the fragments' scattering angle are distributed within ±45°. After changing the detonation position of the charge,the average scattered final velocity of the prefabricated fragments changes. The average scattered final velocity of the fragments decreased in average final velocity by approximately 1.2%-2.5%,as the off-center distance increased under single-point off-center detonation condition. For the dual-point detonation conditions,the average scattered final velocity of the prefabricated fragments showed a trend of decreasing-increasing-decreasing under dual-point detonation conditions. The average final velocity of fragments can be increased by about 5% when the eccentricity distance is increased appropriately. The average scattering angle of the fragments decreased with the increase of the off-center distance of the detonation position for the off-center detonation. Therefore,in order to enhance the damage capability of the warhead,the off-center distance of the detonation points can be appropriately increased for the dual-point detonation method,For the single-point detonation method,the off-center distance should be appropriately reduced. The research results provide reference for the design of prefabricated fragmentation warhead warheads.

In order to study the damage effect of the near-field strong shock wave on the covered charge,the dimensional analysis method on the sympathetic detonation with covered plate was established theoretically. The shock initiation process of covered-pressed TNT was numerically simulated by nonlinear finite element program ANSYS/LS-DYNA. The influence of covered plate thickness,donor charge mass,length-diameter ratio of donor charge on the detonation distance during non-contact explosion was analyzed. The functional relationship between covered-plate thickness and sympathetic detonation distance was obtained by a non-linear least square method,as well as the functional relationship between donor charge mass and sympathetic detonation distance. The results show that the dimensional analysis results are in good agreement with the fitting formula,which fully demonstrates the validity and accuracy of the fitting formula. The calculated detonation distance of the non-contact explosion decreases with the increase of the covered-plate thickness. While the covered-plate thickness is less than 3 mm,the increase of the covered-plate thickness has a greater impact on the sympathetic detonation distance. While the thickness is greater than 3 mm,further increasing the covered-plate thickness has significantly smaller effect on increasing the shock initiation resistance of explosive. When the length-diameter ratio of the donor charge remaining constant,the detonation distance of the non-contact explosion is linear with the donor-charge radius,and cubic with the donor-charge mass. Under the donor-charge mass remains constant,the detonation distance of the non-contact explosion is the largest when the diameters of the donor-charge and the acceptor charge are equal.

Light composite armor is one of the key points modern armor protection system. In order to study the anti-penetration performance of ceramic/fiber composite targets with different ceramic thicknesses,ballistic test of 12.7 mm armor-piercing incendiary projectile penetrating aramid/SiC ceramic/ultra high molecular weight polyethylene fiber composite targets under the same working condition was carried out. The core and target plate were recovered after the test. Then,the crushing characteristics and failure modes of the core and ceramics were observed and analyzed. At the same time,the recovered projectile core and target fragments were screened and weighed,and the cumulative mass distribution of projectile core and ceramic fragments was analyzed. Thus,the anti-penetration performance of ceramic/fiber composite target was characterized. The results show that the head of the core is crushed into powder and the body is crushed into irregular fragments. While the remaining core is not broken and the fracture surface shows the characteristic of regular fracture. It is found that there are regular cleavage fracture characteristics in the remaining core by scanning electron microscope,which indicates that the main failure modes are brittle fracture and local plastic deformation under tensile stress caused by multiple fracture failures. The ceramic crushing form includes annular crack,radial crack and ceramic cone with cone angle generated by the two kinds of cracks interweave. The ceramic cone angle increases by about 11.67% for every increase of 1 mm in ceramic thickness. The ceramic crushing area is divided into crushing zone and crack zone. The crushing zone is the circular area on the target. The crushing area increases by about 11.13% for every increase of 1 mm in ceramic thickness. Based on the statistical analysis of projectile core and ceramic fragments,it is found that the cumulative mass distribution law of projectile core and ceramic fragments accords with the Rosin-Rammler power law distribution function model. With the increase of ceramic thickness,the average characteristic size λ decreases,and the fragmentation degree of projectile core and ceramic increases.

Flight stability has a direct and significant effect on the retention ability and target attitude of explosively formed projectile(EFP),and then affects the penetration power of EFP after long distance flight. In order to obtain an EFP configuration with low resistance and flight stability,a single-tail skirt EFP for supersonic flight(Mach 4-7)was proposed. The effects of structural parameters(tail skirt angle 0°-25°,tail skirt length to total length ratio 0.2-0.7,length-diameter ratio 3-7,solid length-total length ratio 0.2-1)on aerodynamic parameters such as lift coefficient,drag coefficient and static stability reserve of EFP were studied numerically. The results show that lift coefficient and drag coefficient are positively correlated with tail skirt angle,tail skirt length and length-diameter ratio. Statically stable reserve is positively correlated with tail skirt angle and length-diameter ratio,and increases first and then decreases with the increase of tail skirt length. The solid length has almost no effect on the lift coefficient,drag coefficient and pressure center position of EFP,but the solid length affects the static stability reserve by changing the centroid position of EFP. The analysis shows that when the tail skirt angle is 20°,the ratio of the tail skirt length to total length is 0.265,the ratio of the solid length to total length is 0.755 and the length-diameter ratio is 5,the EFP structure of the single tail skirt has low resistance and good flight stability. The influence of Mach number and angle of attack on the lift resistance coefficient and static stability reserve of EFP was studied. The results show that the larger the Mach number,the smaller the resistance coefficient. The larger the angle of attack,the larger the resistance coefficient and the static stability reserve. The research results offer reference for the design of EFP warhead with high penetration performance from the perspective of aerodynamics.

Mines,improvised explosive devices and roadside bombs have become serious threat to vehicle-mounted howitzers(VMH),and the blast wave generated by mine explosion can also cause damage to the cab structure of VMH and endanger the life safety of crew. Because of the significant difference in the response of the shock wave generated by the mines explosion at different positions at the bottom of the cab,numerical simulation of the response process of the cab bottom of VMH under six explosion-shock conditions was carried out. ALE algorithm was used to establish models of soil,air and explosive,and Lagrange algorithm was used to establish the models of cab and chassis of VMH,and the fluid-solid coupling algorithm was used to calculate the propagation process of the explosion-shock wave,as well as the dynamic response of the cab of VMH in this process. The changes of shock-wave pressure,acceleration and velocity at the bottom plate of the passenger's foot position were analyzed,and the maximum shock-wave pressure,acceleration and velocity at the bottom plate of the passenger's foot position were obtained,and the damage to the cab structure under the worst-case operating conditions was analyzed. The simulation results show that the shock wave generated by the mine will make the cab floor produce greater acceleration and speed,and the cab structure will be damaged. In this case,the passengers will be injured. It is necessary to add a protective structure for the cab of VMH. The simulation results can provide reference for the design of cab protective-structure of VMH.

In order to expand the application scope of folding wing UAV and extend the information acquisition ability of underwater platform,an underwater vehicle scheme of carrying UAV for dry launch was proposed by combining the advantages of UUV and UAV. In order to better evaluate the feasibility of launching UAV on the sea,the computational fluid dynamics simulation software StarCCM+ was used to simulate the launching environment of UAV on the sea,and the floating and launching process of UAV was simulated in the simulation environment. The air-bag scheme and the propeller scheme were designed respectively by referencing foreign design experience,and the different sea-conditions,different structural-parameters and attitude parameters were simulated and evaluated,and finally the launching process was simulated under the sea conditions. The results show that the UAV carrier in the state of zero buoyancy underwater can float stably on the water surface under different sea-conditions by the air bag scheme and the propeller propulsion scheme. In terms of UAV launch,the difference between the maximum sinking distance of the air-bag scheme in still water and sea conditions is about 2.5%,and the consistency is better than the error level of the propeller scheme of 30%. The average maximum sinking-distance of the vehicle during the launch of UAV is 0.28 m,which is lower than 0.4 m of the propeller propulsion scheme. In a comprehensive comparison,the air-bag scheme is more stable and reliable.

The engraving process of projectile accompanies the mechanical environment of strong impact,high overload,and high temperature. During this process,the homogeneous brass rotating band undergoes plastic deformation and damage destruction under the action of rifling land,resulting in the copper hanging on the inner surface of the barrel. With the widespread use of the concave hexagonal negative Poisson's ratio honeycomb structure(CHNPRHS),a novel CHNPRHS rotating band was proposed for the purpose of reducing the copper hanging phenomenon,taking advantage of the excellent load reduction and impact resistance of the structure. The finite element model of the rotating band engraving into the barrel was established. The deformation mode and mechanical properties of the CHNPRHS rotating band in the condition of positive propellant were studied. The research results show that the CHNPRHS rotating band satisfies the internal ballistic performance requirements during firing. While the movement of the projectile in the process of engraving is not significantly different from that of the traditional homogeneous brass rotating band. Due to the fact that the CHNPRHS rotating band undergoes three deformation stages of the elastic,plateau,and densification. There is slight damage and fracture on the surface of the rotating band,and it adheres well to the inner surface of the barrel. Compared with the conventional rotating band,the damage and energy consumption of the rotating band during engraving can be reduced by 76.9%. The CHNPRHS rotating band can decrease the occurrence of copper hanging on the inner surface of the barrel,and reduce the surface erosion of the barrel to some extent,thereby improving the service life of the barrel.

To enhance the adaptability of the coil-induction launcher to the shape of the projectile and improve the space utilization by the launcher,an external-armature coil-induction electromagnetic launcher(CIEL)was proposed. Six sets of launcher models under different conditions were established. The influence of the driving-coil inner-diameter and the relative position of the armature on the launcher was studied. Numerical calculation was carried out to solve the magnetic field distribution of the driving coil,and static finite-element-simulation was carried out to calculate the coupling between the driving coil and the armature,and of the force on the armature was theoretically analyzed,and transient finite-element-simulation verification was carried out. The magnetic field calculation results show that the radial magnetic induction intensity inside the driving coil is approximately equal to that outside. The axial magnetic flux surrounded by the external armature is 5.51×10^-5-22.04×10^-5 Wb,and the axial magnetic flux surrounded by the internal armature is 2.81×10^-5-17.39×10^-5 Wb. The peak magnetic-induction-intensity outside the driving coil is 5.38×10^-3-7.32×10^-3 T,and the peak magnetic-induction-intensity inside is 1.57×10^-2～1.93×10^-2 T. The static finite-element-simulation results show that the mutual inductance and mutual inductance gradient between the external armature and the driving coil are about 1.5-3 times greater than those of the internal armature. The transient finite-element-simulation results show that the efficiency of the internal structure is 2.96%-17.57%,and the efficiency of the external structure is 4.94%-19.76%. The magnetic flux enclosed by the external armature is approximately 1.27-1.96 times that of the internal armature. Therefore,while the radial magnetic induction intensity is close,the external armature can obtain greater acceleration force; the magnetic induction intensity outside the driving coil is about one-third of the internal magnetic induction intensity,so the external structure has better electromagnetic protection capability; the energy conversion efficiency of external structures is 12.5%～66.6% higher than that of internal structures,therefore external structures have higher energy conversion efficiency.

The error model best estimation of trajectory(EMBET)based on the constraint of basis function is an important method for post-mission high-precision data processing of external ballistics. It is significant to choose an appropriate basis function for obtaining ballistic parameters and analyzing ballistic characteristics effectively and accurately. To explore the effect of basis function on the accuracy and efficiency of data fusion for external trajectory data,the EMBET data fusion methods characterized by cubic B-Spline basis function and two-point cubic Hermite basis function were compared and analyzed. Firstly,the trajectory was characterized by two basis functions. Therefore,the data fusion for trajectory measurement data was transformed into the estimation of basis function coefficients. Thus,the fusion model of external trajectory was solved. Combining the theoretical ballistic characteristics of weapon systems,the data fusion methods based on the two basis-functions were simulated and compared through fusion instance. The accuracy was also compared and analyzed according to the ballistic coordinate,ballistic velocity and error detection of measurement elements. The simulation results show that,under the same conditions,both of the data fusion methods based on the two basis functions can achieve high-precision external ballistics coordinate parameters. But the data fusion method based on the basis function of B-Spline is more advantageous in compression of estimated parameters and calculation efficiency. Furthermore,the calculation accuracy of its ballistics velocity parameters is higher than that of the other method.

Submarine-launched missile is an important component of a nation's strategic deterrent force. As the initial launch stage,the ejection process of submarine-launched missile involves complex fluid dynamics problems such as the huge impact of high-pressure gas on the bottom of the missile and the strong interaction between gas and water,which is of great significance to research. Based on the three-dimensional unsteady compressible numerical simulation method,VOF multiphase flow model and overlapping grid technology were utilized to study the acceleration during the process of wedge entry and the flow field and motion characteristics under different conditions during the ejection process of submarine launched missiles. The simulation results show that the higher bottom pressure leads to the larger exit velocity,the greater axial force,the faster attenuation of the velocity,the larger the lateral displacement of the projectile,and the greater lateral load. The incoming flow gives rise to a decrement in gas on the upstream side and an increment in gas on the downstream side. The asymmetry of the flow fields on both sides creates lateral forces and rotational moments with respect to the center of mass,causing the projectile to deflect in the direction of the incoming flow. The higher inflow velocity leads to the greater lateral acceleration of the projectile and the larger possibility to deviate. The research results can provide technical support for the ballistic design of submarine launched missiles.

In order to solve the problem of insufficient lift of strake wing and explore the effect of wing body interference on the lift of strake wing projectile,numerical calculation method was utilized to identify comparison among normal force of strake-wing body combination model,conventional-wing body combination model,only strake-wing model,only conventional-wing model and only body model with angle of attack. The results show that normal force of wing body combination model is greatly increased by wing body interference in subsonic range due to the larger pressure differences between the upper and lower surfaces. It is resulting from the faster velocity caused by larger vorticity in upper surface and the slower velocity caused by block in lower surface. At Ma=0.6 and α=20°,the normal force of its body is increased by 195%,and the average normal force is increased by 46%. At supersonic speeds,due to the small lift of corner vortex in upper surface compared to the strake only model,the wing body interference has a limited lift on normal force of strake. Wing body interference is mostly located on the wings and bodies near the root wings. Strake has a long chord,and affected area is large,so the normal force of strake wing body combined model influenced by wing body interference raises more.

To study the penetration performance and behind-target damage-abilities of tungsten fiber/Zr-based bulk metallic glass matrix composite(WF/Zr-MG)penetrator penetrating the finite-thickness targets,the ballistic experiment on 45 steel target impacted by WF/Zr-MG rod with length-to-diameter ratio of 15.4 and volume fraction of 80%(a tungsten fibre diameter of 0.3 mm)under the impact velocity of(1 600±20)m/s was carried out and compared with 91W rod. The macroscopic damage effects on the 45 steel target and the subsequent-effect target were analyzed,and the damage and fragment scattering characteristic parameters of behind-target were obtained for two kinds of materials rods,and the differences in the damage mechanisms of two types of rod hehind-target were discussed. The research results show that compared to the 91W rod,the WF/Zr-MG rod has a structural “self-sharpening” characteristic during the penetration process,and forms smaller crater-diameters in the target plate,dissipates less energy during penetration,and exhibits higher penetration performance. Additionally,due to the asymmetric tensile and compressive properties of WF-MG rod,the tod immediately breaks and disperses while exiting from the target,so the damage area caused by WF/Zr-MG rod on 2A12 subsequent-effect target located 0.5 m from the target plate is 1.7 times and 1.63 times the damage area of the 91W rod,respectively. The number of effective fragments is 2.76 times and 1.61 times that of the latter,respectively. The fragment scattering angle and the maximum break size of the subsequent-effect target are both greater than those caused by the 91W rod,increasing the damage capability on behind-target objectives.

In recent years,data-driven methods have received extensive attention and research,and data-driven provides a new research paradigm for the development of internal ballistics,which has a broad application prospect and development potential. This paper summarizes the relevant research results of data-driven methods in the field of internal ballistics in recent years,and mainly introduces the data-driven internal ballistic modelling technique and the data-driven internal ballistic performance optimization method. The paper also discusses the challenges faced by the related research and points out the directions worthy of further research in the future.

To study the influence of fragment shape,mass and other factors on the velocity attenuation law of prefabricated fragments in the flight process,the flying velocity test was conducted on spherical fragments,cuboid fragments and cuboid fragments recycled from static explosion tests using 25 mm ballistic-gun. Among them,the diameters of the spherical fragments are 7 mm and 8 mm respectively,and the masses are 3.9 g and 4.7 g respectively; the size of the cuboid fragment is 8 mm×8 mm×7.05 mm,and the mass is 7.94 g. Using Doppler radar velocity-measurement technology,the real-time velocity data of fragments during flight were measured,and the variation law of fragment velocity with time was analyzed. The variation law of fragment velocity with displacement was obtained by numerical analysis method. Finally,the fragment velocity-attenuation-coefficient,the relationship between the velocity attenuation coefficient of spherical and cuboid fragments and the Mach number(Ma)were obtained through data fitting. For spherical fragments,the velocity attenuation coefficient shows a decreasing trend with the increase of fragment radius. The velocity attenuation coefficients of 8mm spherical fragments were compared with that of 8 mm×8 mm×7.05 mm cuboid fragments. The result shows that the masses of the two types of fragments are significantly different,but the average velocity-attenuation-coefficients are close. Within the initial velocity range of 1 300-2 100 m/s,compared to cuboid regular fragments,the average velocity-attenuation-coefficient of cuboid fragments recovered from static explosion experiments is larger,indicating that they experience greater air resistance and faster velocity attenuation during flight in the air. The shape of the cuboid fragments recycled from the static explosion test is closer to that of fragments generated after the actual warhead explosion,and the test result has greater reference value for the design and power evaluation of the warhead.

To improve the propulsion safety of large-caliber solid propellant guns,the ignition system usually includes a primer and a flash tube in the axis of chamber. The combustion and flow of ignition propellant can be illustrated as a one-dimensional two-phase flow model. Combined with the one-dimensional two-phase model of main charge,the double one-dimensional two-phase model can be established for the simulation of interior ballistic process. Under a certain charge condition, the stress and fragmentation characteristics of the propellant particles were numerically simulated with the experimental stress and fragmentation function of the propellant particles in the bore. The simulation results show that the degree of fragmentation increases from 2.184 to 2.781,with an increase of 27.3%,as the mass of propellant in flash tube increases from 90 g to 110 g. The degree of fragmentation decreases from 2.487 to 1.35,with a decrease of 45.7%,as the length of the flash tube increases from 0.3 m to 0.38 m. The degree of fragmentation decreases from 2.487 to 1.997,with a decrease of 19.7%,as the diameter of the flash tube increases from 30 mm to 35 mm. The increase of mass of propellant in flash tube will lead to the increase of fragmentation in the charge bed,and the increase of the length or diameter of the flash tube will reduce the charging density of propellant in the flash tube,resulting in the decrease of fragmentation in the charge bed.

In the context of non-rolling control missile testing engineering,an optimization scheme was proposed for the placement of trajectory tracking positions to improve the accuracy of inconsistency correction in trajectory tracking positions without rolling control,taking the multi-beam radar measurement system as an example. Firstly,based on the tracking location information obtained from external measurement data,the correction amount of the tracking location was calculated by using measurement data from optical equipment or telemetry equipment to calculate the center position parameters of the missile inertial-navigation-platform. Secondly,the inconsistency correction error of the non-rolling control missile tracking part was analyzed by applying the principle of error transmission,and a method was proposed to improve the accuracy of inconsistency correction of the non-rolling control missile tracking part by deploying two tracking parts. Then,the influencing factors of the non-rolling control missile on the accuracy of inconsistent correction of the tracking position were separated. On this basis,the angle and distance of the tracking position were optimized to reduce the contribution of the non-rolling control missile to the correction error. Finally,simulation experiments were carried out by taking the optimization of two tracking-point layouts as examples. The results show that the proposed optimization scheme for tracking point layouts effectively improves the accuracy of tracking-point inconsistency correction in the background of non-rolling control missile,verifying the effectiveness of the optimization scheme.

To study the influence of thickness on dynamic response and energy-absorption characteristics of foamed concrete(FC)under explosion-load impact,the numerical calculation of anti-explosion of FC under 0.8 m/kg^1/3 ratio-detonation-distance and 0-30 mm thickness was carried out by using finite element software. Subsequently,the anti-explosion tests of FC with thickness of 0 mm,10 mm,20 mm and 30 mm,were carried out to verify the accuracy of the numerical calculation. Through numerical calculation,the damage form and energy-dissipation mechanism of FC under the impact of explosion-load were studied,and the ability of FC to absorb explosion-wave energy was quantitatively analyzed,and the law of the energy absorption characteristics of FC and the deformation response of aluminum alloy plate on the back influenced by the change of thickness of FC was obtained,and the corresponding engineering-calculation-model was derived. The results show that,the size of the FC crushing zone gradually shrinks with the increase of thickness. The FC crushing-zone only accounts for 2.9% of the overall volume when the thickness is 30 mm. FC can effectively absorb and dissipate the energy of explosion wave,and its energy-absorption capacity increases with the increase of thickness. The foam concrete with thickness of 5-30 mm can absorb 42.8%-91.9% of explosion wave energy respectively. The displacement response of aluminum alloy backplane steadily shrinks as FC thickness increases. While the thickness of FC is 30 mm,the displacement response of the center of the aluminum alloy backplane drops to 3.2 mm,which is only 12.6% of that without FC.

In order to deeply research the wear mechanism of driving bands and explore the essence of the plastic deformation of driving bands,a comparison was made on the surface morphology,composition,microstructure and hardness of three driving-bands of 155 mm caliber artillery. The research results show that although the driving bands have different structural designs,compositional makeups and diverse service conditions,their microstructure distributions present common patterns after being in service,and their wear degrees are closely related to spatial positions. The wear on the non-driving side is generally lighter,and its microstructure is mainly equiaxed structure. Due to friction,fine-grained microstructure is generated at the top of the protruding part of driving band,while the internal microstructure morphology remains basically unchanged. The wear on the upper part of the driving side is the most serious,and the microstructure evolution presents a spatial distribution of fine-grained microstructure,fibrous microstructure,elongated microstructure and equiaxed microstructure from the surface to the inside. The wear degree at the bottom of the driving side is lower than that of the upper part. During the working process of the driving band,the deformation is concentrated on the surface,and the internal microstructure morphology above 200 μm from the surface hardly changes. The hardness analysis shows that the hardness on the non-driving side is similar to that inside the driving band,while both the upper part of the protruding position of the driving band and the upper part of the driving side present a "soft-hard" structure. Among them,the hardness of the fine-grained microstructure is the lowest; the hardness of the fibrous microstructure is the highest; the hardness of the equiaxed microstructure is in the middle. Among the three driving-bands,the wear of H96-2 is the most serious,while wear of H96-1 is the least.