In order to study the penetration resistance of the corrugated aluminum plate filled with ceramic rod composite structure under different impact positions,a multi-ceramic-rod reinforced composite structure composed of trapezoidal corrugated aluminum plate was designed,followed by ballistic impact test and numerical simulation. By comparing the failure mode,energy absorption efficiency and velocity variation patterns under different impact points,the anti-penetration mechanism of the structure at three typical positions was obtained. The results show that the energy absorption of the multi-ceramic-rod reinforced trapezoidal corrugated aluminum plate is composed of the crushing energy dissipation of the ceramic panel,the shear expansion and plastic deformation of the trapezoidal corrugated aluminum plate,the fracture and crushing of multiple ceramic rods,and the tensile failure of the PE backplate. The ballistic resistance exhibits significant position-dependent characteristics,particularly influenced by ceramic rod spatial distribution and backplate support capacity. In composite structures,compared the midpoints of the upper and lower bases of the trapezoid with the midpoint of the oblique side,the protective area of the ceramic rod is larger,the ceramic crushing area is larger,and the anti-penetration ability is stronger. During high-velocity penetration of the target plate,due to the common constraints of the aluminum plate and the PE backplate behind the ceramic rod,the ceramic fragmentation near the midpoint of the lower base is more thorough compared to the upper base,leading to a further improvement in anti-penetration performance. The anti-penetration ability is improved,resulting in 20.45% and 8.14% increases in ballistic limit velocity compared with the other two places. The research results provide a theoretical guidance for the design of the reinforced corrugated structure.

The rotating band engraving process during artillery firing is transient in duration,which involves intense interactions between the rifling and the rotating band,exerting significant influence on the initial state of projectile motion within the barrel. Standardized modeling and setup procedures is a critical prerequisite for comparing the dynamic responses of rotating band engraving under different internal bore structures. Regarding this issue,basic parameterization of the finite element analysis process for rotating band engraving was studied. Specifically,mesh node coordinates were calculated through scripting,and the correspondence between mesh nodes and elements was established to generate finite element models of rifled barrels. Additionally,the execution logs of finite element software were compiled to proceduralize the modeling of the projectile rotating band and the preprocessing of rotating band engraving. A GUI plugin capable of one-click generation of rifled barrel and projectile rotating band finite element models,along with automated preprocessing configurations,was developed. The engraving processes under varying internal bore structural parameters were analyzed. The study focused on the effects of structural differences in rifling profiles,land height and land width on the rotating band engraving process. Dynamic simulation shows that in hybrid rifled barrels,the resistance encountered by the rotating band during engraving is smaller than that in uniform-twist rifled barrels,and the maximum stress at engraving completion is also lower. Reduced land height or narrowed land width decreases the internal bore resistance during rotating band engraving,resulting in faster engraving velocities.

Vulnerability is an important concept of target performance and a critical target characteristic,both in traditional fields,modern scientific and technological domains,and the military domain. At present,there are still prominent issues such as lack of unity,clarity and accuracy in the concept of target vulnerability. It brings a lot of problems to the research on target vulnerability,especially the assessment of target vulnerability. To clarify the related concepts of target vulnerability,the theoretical analysis,example illustration and other methods were used to explore it. A clear and precise definition of target vulnerability was provided,which refers to the degree of difficulty for a target to sustain functional damage under the conditions of being detected/perceived,subjected to damage element,and experiencing physical damage. The vulnerability includes perceived vulnerability,attack vulnerability,physical vulnerability,and functional vulnerability. Among these,physical vulnerability further includes structural vulnerability and material vulnerability. This definition is the broad sense of target vulnerability. In actual use,the narrow-sense definition of target vulnerability is mainly adopted,which refers to the degree of difficulty for a target to be damaged under the single action of a certain damage element or the combined action of multiple damage elements. This definition does not consider perceived vulnerability and attack vulnerability,but mainly considers physical vulnerability and functional vulnerability. Based on the clear definition of target vulnerability,the characteristic quantity/measurement of target vulnerability,the relationship between target vulnerability and weapon ammunition effectiveness,and the relationship between target damage probability and target survival probability were analyzed. The significance and method of target vulnerability research were discussed. This study has important theoretical reference significance for related research on target vulnerability.

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.

In order to accurately calculate the recoil efficiency of a certain aircraft gun with multi-row oblique-side-holes muzzle-brakes,the numerical simulation on muzzle flow-field was carried out,considering the effect of projectile on propellant gas expansion and the acceleration effect of oblique-side-holes on propellant gas. The correctness of this numerical simulation method was verified by comparing the numerical simulation results of the muzzle flow field of a 12.7mm weapon with experimental results. The two-phase-flow internal-ballistic model of 30 mm aircraft gun was calculated numerically,and the flow state in the bore while the projectile reaching the bore position was obtained under the initial condition.The three-dimensional N-S equations of the muzzle flow-field were established,taking into account the interaction between the projectile and the propellant gas. A three-dimensional moving-grid method combining a polyhedral mesh for the stationary region and a hexahedral structured mesh for the moving region was adopted to numerically simulate the three-dimensional transient flow of the propellant gas when the projectile passes through each row of oblique-side-holes,which was compared with the case without considering the projectile motion. The results show that the oblique-side-holes can introduce high-pressure propellant gas into the barrel and generate supersonic airflow from the oblique rear,thereby producing a large recoil impulse. The recoil efficiency reaches 38.4%. The projectile impedes the expansion of propellant gas,resulting in stronger conical oblique shock waves at the oblique-side-holes. As a result,more propellant gas is ejected from the oblique-side-holes,increasing the recoil impulse. Therefore,projectile motion must be considered in numerical simulations of this type of muzzle brake. This research provides reference for the design of new multi-row oblique-side-holes muzzle-brakes and the dynamic matching between cannons and aircraft.

In order to maintain excellent aerodynamic characteristics of extended-range guided projectiles in the entire flight airspace while enhancing their maximum range and flight efficiency,morphing vehicle technology was applied to large-caliber extended-range guided projectiles. The aerodynamic shape and variable swept wing of a variable swept wing extended-range guided projectiles was designed. Furthermore,a trajectory optimization methodology specifically adapted for extended-range guided projectiles featuring continuous variable swept wing capability was proposed. By introducing a deformation parameter to characterize the variation of the fin swept angles of the projectile,a longitudinal dynamics model for extended-range guided projectiles with variable swept wing was constructed. Particle swarm optimization algorithm was employed,with maximum overall lift-to-drag ratio as the objective function,to simultaneously optimize wing sweep angles and rudder deflection angle. Ballistic simulation was carried out for the variable swept wing extended-range guided projectiles and its fixed shape respectively. The simulation results show that the variable swept wing extended-range guided projectiles can continuously adjust wing sweep angles according to the flight velocity of the projectile,thereby modulating aerodynamic drag and lift to maintain optimal lift-to-drag ratio characteristics throughout the ballistic glide phase. Compared to the guided projectile with fixed shape,the guided projectile with variable swept wing achieves significant range increase of 8.9%. The research method provides a theoretical foundation and reference for the optimal design of the ballistic trajectory of the continuous variable sweep wing extended-range guided projectiles.

The traditional impact point prediction guidance methods require a lot of iterations in the solution process,and the real-time processing ability of information is poor. The impact point prediction model based on machine learning method can reduce the prediction time and improve the prediction accuracy. However,the existing impact point prediction model is mostly trained by the uncontrolled flight data of the projectile,without considering the influence of control force and torque,resulting in a remarkable difference from the actual flight state of the guided projectile. In this paper,a guidance and control method based on machine learning was proposed. The flight state parameters of the projectile in the controlled state were used as the training set,and the controlled landing point prediction model was established. Combined with the proportional-differential control law,the guidance and control process based on this landing point prediction model was constructed. The simulation results show that the impact point prediction model trained by BP neural network can accurately predict the impact point,and the proposed guidance and control method can achieve high-precision guidance and control. The relative error of the range direction of the hit point is about 0.01%,and the relative error of the sideslip direction is about 3.1%. The feasibility and effectiveness of the designed guidance and control method are verified,which can provide reference for the in-depth application of machine learning method in the field of controlled projectile technology.

The coupled aerodynamic heating and ablation deformation on the surface of hypersonic projectiles induce significant aerodynamic configuration evolution,which subsequently impacts flight stability and external ballistic performance. Therefore,multi-condition aerodynamic heating calculation method for different projectile structures,flight conditions,and environments is crucial for optimizing thermal protection system and advancing engineering applications in hypersonic projectiles. Based on the existing aerodynamic heating calculation methods for hypersonic projectiles flying at zero angles of attack,a spherical coordinate system was established in response to the stagnation point offset phenomenon induced by angles of attack in spherical cone. The conversion relationship between the projectile coordinate system and the velocity coordinate system was utilized to carry out aerodynamic heating simulation analysis of three-dimensional spherical cone shaped projectiles flying at angles of attack. The distribution of heat flux density on the busbar of the spherical head and the conical body was obtained. The heat flux density and heating status were compared with and without an angle of attack. The calculation results are basically consistent with experimental data. The simulation results show that the heat flux density of the spherical head is much higher than that of the conical body,and the heat flux density of the windward busbar with an angle of attack is greater than that of the leeward side. The calculation method used in this article can satisfy the accuracy and speed requirements for simulation and design of ultra high speed flight trajectories. The proposed calculation method and results provide a foundation for the rapid coupling calculation of aerodynamic ablation and external trajectory of hypersonic projectiles in the future.

Aiming at the dynamic characteristics of missile vertical cold launch under ship swaying motion,based on the theory of interior ballistics,a coupled interior ballistic theoretical model under ship swaying motion was established. Based on coupled and uncoupled interior ballistic models,interior ballistic calculations of ship unidirectional and composite motion were carried out for typical scenarios. The results imply that under six-level sea condition,compared to the uncoupled model,the upper and lower limit of the range of the outlet velocity obtained by the coupled model change by -0.04 m/s and 0.05 m/s,when the ship performs rolling motion. When the ship performs pitching motion,the upper and lower limit of the range of the outlet velocity obtained by the coupled model change by -0.46 m/s and 0.48 m/s. When the ship performs heaving motion,the upper and lower limit of the range of the outlet velocity obtained by the coupled model change by -0.43 m/s and 0.47 m/s. When the ship performs a composite motion of roll,pitch and heave,compared to uncoupled model,the upper and lower limit of the range of the outlet velocity obtained by the coupled model change by -1.02 m/s and 0.98 m/s. Compared to the uncoupled model,the range of outlet velocity obtained by the coupled model is significantly narrowed. The model can provide reference for the simulation of vertical cold launch interior ballistics of missiles under ship motion.

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.

The high-temperature,high-pressure,partially reacted jet ejected from the deflagration launcher undergoes secondary reactions with the ambient air when entering the initial the chamber,generating intense thermal shock and ablation effects on the launcher. To mitigate the adverse impacts,the influence of secondary reactions on the deflagration launcher and projectile interior ballistics was investigated in this paper. Thermodynamic properties of the launcher's deflagration products were calculated using the minimum free energy method. The chemical reaction mechanism of secondary reactions within the initial chamber was described based on the finite-rate/eddy-dissipation model. The projectile's motion was simulated via a dynamic mesh layering technique,establishing a secondary reaction flow model in the initial chamber with moving boundaries. The validity of the model was verified through comparison with experimental data. Research results indicate that chambers experiencing secondary reactions exhibit faster temperature rise rates and higher peak temperatures compared to non-reaction chambers. As O₂ in the chamber depletes,temperatures gradually decrease. The energy released from secondary reactions enables the projectile to achieve greater acceleration in shorter time intervals while maintaining peak acceleration levels briefly. Consequently,the projectile attains higher velocity and greater displacement within the equivalent timeframe. Expanding the initial chamber volume can alleviate excessive projectile loading by reducing acceleration growth rates and peak acceleration magnitudes. These findings provide theoretical foundations for the design of deflagration launcher and interior ballistics performance.

During the vertical movement underwater,vehicles are highly susceptible to the marine environment,leading to unstable motion postures. Uncontrolled and unpowered launching has become inadequate in deep water and strong disturbance conditions. PID control,dynamic fluid body interaction,and dynamic nesting/sliding mesh techniques were employed to construct an integrated numerical calculation method that couples fluid dynamics,motion,and control in this paper. The motion process of underwater controlled-propulsion vehicles,analyzing the evolution of tail cavitation and ballistic characteristics under different tail jet pressures(6 MPa,10 MPa,12 MPa)were numerically simulated. The results show that during the merging process of supersonic jets and tail cavitation,the tail gas mass breaks due to interface instability and nozzle swaying,with the break occurring earlier as nozzle pressure increases. Inside the tail spray cavitation,a complex wave system structure exists. At higher nozzle pressures,the jet is under-expanded,resulting in multiple high and low-pressure areas formed by expansion and compression within the gas bubble. Over time,a Mach disk perpendicular to the axis appears near the nozzle exit. Additionally,the larger the nozzle pressure,the greater the disturbance torque caused by the tail spray flow. Increasing the nozzle pressure from 6 MPa to 12 MPa reduces the maximum deviation angle during motion by 18.5%,decreases the overshoot from 32% to 22%,resulting in less attitude fluctuation and better ballistic stability.

In order to evaluate the damage effect of block charges with different masses on the surface of concrete pier body,the damage characteristics of the concrete pier under the action of contact explosion were studied by numerical simulation,and the damage effect of the concrete pier body was evaluated by the equal damage curve,and the characteristics of the damage area of the top surface,side and side edge of the pier body under the action of contact explosion were obtained,and then the influence of charge quality and placement position on the damage effect of pier body was revealed. By establishing the calculation model of vulnerable volume,the variation curves of the remaining volume of concrete pier body with the charge mass under the action of contact explosion on the top surface,side and side edge were obtained. On this basis,the block charge with different masses was compared in 8 different positions on the concrete pier body during contact explosion,and the number of large fragments and the maximum fragment volume after the explosion were studied. The result shows that the shape of the damage area on the top surface and side of the concrete pier is approximately circular,and its center coincides with the center of the top surface. The shape of the damage area on the side edge is approximately elliptical. When the charge explodes in contact with the top surface,side and side edges,the damage effect at the center position is the best. When the charge mass is 1-3 kg,the damage effect of the explosive exploding at the geometric center of the top surface of concrete pier is the best. When the charge mass is greater than 3 kg,the damage effect of the explosion at the side geometric center is the best.

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 study the auto-initiation phenomenon of rotating detonation of high-temperature hydrogen-rich gas,the experimental study was carried out. The influence of equivalent ratio on the propagation characteristics of high-temperature hydrogen-rich gas rotational-detonation-wave was explored by analyzing the typical characteristic-parameters,and the equivalence-ratio range of the successful auto-initiation of high-temperature hydrogen-rich gas to form a rotational detonation wave was obtained,and the influence of equivalence ratio on the self-initiation delay time was analyzed. The results show that the intensity of the initial rotational detonation wave formed by auto-initiation is weak,and the propagation direction and propagation mode will change. However,through the self-adjustment of the rotational detonation,the stable self-sustaining propagation of the rotational detonation can be realized finally. While the flow rate of pre-fired oxygen is about 8 g/s and the air flow-rate is 270 g/s,within the equivalence-ratio range of 0.85-1.98,the high-temperature hydrogen-rich gas can form a stable rotational detonation wave through self-detonation. When the equivalence ratio is greater than 1.52,the rotational detonation wave is in a single-wave mode,and with the decrease of the equivalence ratio,it changes to a mixed mode,that is,under the same working condition,the single-wave,dual-wave mode and single/double-wave transition mode appear irregularly alternately. When the equivalence-ratio decreases to about 0.96,the rotational detonation wave presents a stable two-wave mode,and with the increase of the equivalence ratio,the auto-initiation delay time decreases from 138 ms to 106 ms. The propagation velocity of the rotational detonation wave increases first and then decreases with the increase of the equivalence ratio. The maximum value of the wave velocity occurs when the equivalence ratio is 1.33,and the wave velocity is 1 278 m/s.

Upon primer ignite the firing charge,the combustion gases propel gunpowder particles through controlled axial propulsion. The sloping chamber,which is a gradual shrinkage section between the chamber and the barrel bore,will inevitably be subjected to the irregular collision of the gunpowder particles,resulting in localized erosive wear. In the initial ballistic stage,with high chamber pressure,fast particle velocity and large particle size,the erosive wear caused by the impact of gunpowder particles on the sloped chamber is more prominent. In order to focus on this collision damage effect,according to the characteristics of particle motion,collision and gas-solid two-phase flow in the initial ballistic phase,a three-dimensional unsteady gas-solid two-phase flow model was established based on the Euler-Lagrange approach,using the computational fluid dynamics-discrete element method(CFD-DEM)coupled method. Numerical simulation of the erosion and wear of the gunpowder particles on the sloped chamber of a 155 mm artillery was carried out. The results show that the erosive wear in the starting section of the sloping chamber is significant and has an annular distribution,while the erosive wear in the rest of the area is minor and has an irregular cloud-like distribution. The mass loss of the sloping chamber increases exponentially with time. When the taper of the sloping chamber is increased from 1/10 to 1/5,the mass loss of the sloping chamber increases with the increase of taper,and the larger the taper is,the larger the rate of mass loss is.

In order to study the tail-fin opening characteristics of the image terminal-guided-projectile,according to the structure characteristics and action principle of tail-fin,the movement process of the piston after starting and the rotation process of tail-fin were studied,which were coupled with the bore process and the after-effect process of the terminal guided projectile. The numerical simulation was carried out for the certain image terminal-guided-projectile. The pressure of projectile base and cylinder,displacement and velocity of projectile,displacement of piston,opening angle of fin and gas resistance were obtained. The results show that the relative errors of maximum pressure on the base,muzzle velocity,tail opening position and tail-fin opening angle are 3.2%,0.7%,4.7% and 5.7% respectively,which are within the allowable range. The related simulation curves are consistent with the actual change law,verifying the rationality of the model. On this basis,the influence of charge and pore diameter on tail-fin opening characteristics of image terminal-guided-projectile was analyzed from the perspective of equipment production and firing use,and the specific guidance was given. The research results can provide theoretical and data support for structure optimization design,strength check and abnormal mechanism research of the tail structure of the image terminal-guided-projectile,and also provide reference for development and use of other new-type cylinder-opening tail-fin projectiles.

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.

The downwash phenomenon of canard missile at low speed was studied by numerical calculation method and PIV experiment. The aerodynamic parameters and flow field of canard-shaped missile were calculated and analyzed under the condition of free-stream Mach number of 0.03(10 m/s)and 0.1(34 m/s). The results show that the downwash phenomenon of the canard missile is mainly affected by the shedding vortex of the canard with the downwash flow on the downstream flow field at low speed. A symmetrical effect is generated without the rudder deflection angle. In addition,the influence of the downwash phenomenon on the roll characteristics of the whole missile was explored when the canard was rolled(horizontal canard differential deflection). It was found that the roll reverse effect occurred. The main reason is that,the shedding vortex at the trailing edge of the horizontal canard rudder is asymmetric when the horizontal canard rudder is differentially deflected,so the downstream flow field is also asymmetric. That is,the shedding vortex of the canard rudder will interact with the vortex attached to the missile body and the tail,so that the area of the low-pressure zone above the two horizontal tails is asymmetric,and the normal force provided is not equal,and finally the tail produces a rolling moment opposite to the canard rudder control direction. With the increase of the attack angle,the reverse rolling moment generated by the tail fin is gradually greater than the forward rolling moment provided by the canard,leading to the rolling effect.

Cased telescoped ammunition(CTA)is a novel type of ammunition which adopts a two-stage ignition combustion technology. The first-stage ignition provides the projectile with a certain initial velocity along the guiding barrel in the barrel,impacting the slope of chamber. While the second-stage ignition generates propellant gas to drive the projectile out of the barrel at high speed. To deeply study the internal ballistic characteristics of the two-stage ignition combustion technology in CTA,a 40 mm short barrel experimental platform was designed and constructed. High-speed video recording and a pressure sensor were utilized to measure the impacting velocity and pressure of the sloped of chamber during the test. The test results show that the projectile impacts the sloped of chamber with a velocity of 22 m/s after the first-stage ignition and stop at the sloped of chamber. Then,the projectile flies out of the barrel quickly after the two-stage ignition is activated. Additionally,a zero-dimensional internal ballistic numerical model of the two-stage ignition of the CTA under the test conditions was established to simulate the two-stage ignition process of the CTA under identical loading conditions. Comparative analysis between numerical simulations and experimental data validated the accuracy of the proposed model. The internal ballistic performance of the 40 mm armor-piercing projectile of CTA was simulated to analyze the effects of different loading charges on the projectile movement process. This study provides a reference for the subsequent research on the two-stage ignition technology of the CTA.

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.

As a structure with excellent mechanical properties and multifunctional characteristics,the lattice structure has the characteristics of high strength,high energy absorption,and the like. In order to study the anti-penetration performance of the triply periodic minimal surface(TPMS)structure,we established lattice structure models of the Diamond and Gyroid types based on this structure. Silicon carbide ceramics were selected as the matrix material of TPMS structure,and its anti-penetration performance was studied by the ABAQUS finite element software. The research results show that under low-speed penetration,the Diamond structure significantly improves energy absorption,while the asymmetrical forces generated during impact and the erosion of the projectile in the Gyroid structure can effectively change the penetration angle. Aiming at Gyroid structure,finite element simulation was carried out under different working conditions,such as different impact points,different incident angles and increasing target thickness,and the influence of the change of incident angle on the anti-penetration performance of the Gyroid structure was analyzed. The result shows that the deflection degree of the ejection angle decreases first and then increases with the increase of the incident angle. In addition,when the projectile impacts the spiral surface of the concave Gyroid structure,the ejection angle of the projectile can be obviously changed. After increasing the thickness of the Gyroid structure by 50%,the change of bullet ejection-angle increases by 176.92%,and the absorbed energy increases by 78.26%. The Gyroid structure can effectively change the motion attitude of the projectile through its unique curved-surface structure. The research results provide certain reference significance for lightweight armor design.

The complexity and changeability of modem air-combat conlrontation makes air-combatdecisions fuzzy and changeable. Elfeelive trajectory prediction can greally improve the accuraey oldecision-making. Aiming at the characteristies of complex time series in air-combat trajectory prediction , atrajeetory prediction method integrating short-time Fourier transform( STFT ) and multi-stream transformernetwork was proposed to improve the accuraey of predicting air-combat maneuver trajectory. During air.combat maneuvers, the trajectory of aireralt changes frequently and complexly. Therefore , the trajectorydata were first preprocessed by high-order difference to eliminate noise and relain the spatiotemporalcharacteristies of trajectory. Subsequently,the short-time Fourier transform was used to extraet frequency-domain features of the preprocessed trajectory and analyze the dynamic changes of the trajectory. In orderto belter capture the dilerenees between position trajeetory and allilude trajectory ,a trajectory decouplingstrategy was designed to process these two types of trajectories separately. Then,the transformer nelworkbased on the multi-stream dynamic altention mechanism was used to process these spatiotemporafeatures ,thereby capluring the deep dependencies in the flight trajeetory. The network weights multiple data streams through multi-head attention mechanism, enhaneing the model's ability to capture the spaliotemporal dependeneies of dilerent data streams. Experimental results show that compared totraditional prediction methods,the proposed method has a 3.88%6 improvement in prediction accuracy. Thecombination of S'TF'T and multi-stream transformer elfeelively improves the predietion aceuraey of complexair-combat maneuver trajectory , verilying its applicability in high-precision air-combat scene prediction.

To study the thrust performance of underwater detonation engine(UDE),the thrust calculation method for the simplified UDE model was derived. Based on the VOF multiphase-flow model,the UDE with different nozzle-configurations using air as oxidant and gasoline vapor as fuel was numerically simulated. The thrust source of UDE and the propulsion performance of the engines under different equivalence ratios and nozzle configurations were discussed. The results show that the thrust sources of UDE mainly include three parts:internal thrust wall,annular thrust wall and nozzle wall. The thrust of internal thrust wall contributes more than 67% to total thrust,and the thrust of annular thrust wall contributes more than 16% to total thrust. The complex wave system and detonation products at the engine outlet interact with the engine wall,creating multiple peaks in the thrust curve of UDE. After installing different nozzles,the nozzles have a significant effect on the improvement of thrust performance. The convergent nozzle can enhance the intensity of the reflected shock wave of underwater detonation,but the negative thrust brought by the nozzle wall reduces the specific impulse and average thrust by 11.31% compared with the straight nozzle. The expansion nozzle weakens the transmission shock wave and reflection shock wave of underwater detonation,but the increase of the pressure area of the nozzle increases the specific impulse and average thrust by 28.09% compared with the straight nozzle,significantly improving the propulsion performance of UDE.