Gun Barrel Research Articles

TRENDS IN THE DEVELOPMENT OF CONTROL SYSTEMS FOR GEOMETRIC PARAMETERS OF GUN BARREL

The article shows the relevance of control of the geometric characteristics of the gun barrel. The types of barrels, their qualitative advantage during firing, as well as devices for monitoring the internal characteristics are considered. The functional shortcomings of the existing devices are identified and a schematic image of the multifunctional device under development is presented. Method of measuring the surface of the barrel is described.

Study on Dimension Measurement for Gas Guide Groove of Gun Barrel

Abstract An automatic measurement system based on the stationary wavelet transform (SWT) of vibration signal is developed to obtain the depth and width of gas guide grooves in the gun barrel. The system consists of the programmable logic controller module used to control the motions of system components, a mechanical apparatus used to fix the gun barrel and position the transducer, and a measurement device used to capture and analyze the measured data. With the SWT, the interference noise, baseline wander, and interference harmonics are successively eliminated from the captured displacement signal. Afterwards, the peak and valley points are detected out, which, respectively, represent the information of groove depth and of groove width. Finally, the dimensions of the gas guide groove are determined according to the points detected out and the calibration information. In the experiment, the steps of data processing are provided in detail, and the analysis results show that the measuring error is less than 3 %, which can meet the actual requirements.

Heat Transfer Simulation of Large Caliber Gun Barrel

During the continuous firing of artillery, the inner wall of the barrel will experience a continuous rise of temperature, which has much to do with the ambient temperature and the way it cools. For artillery using combustible cartridge, the temperature rise of the barrel’s interior wall will have a great impact on the safety of combustible cartridge during successive shots. The finite element model of gun barrel was established by ANSYS software while the convection heat transfer in the inner and outer walls of the barrel and the heat transfer in the barrel wall were simulated. This paper observed the temperature variation of the inner and outer wall of the barrel under different ambient temperatures and different cooling methods, revealing that the higher the ambient temperature, the faster the barrel temperature rises. Different cooling methods have little influence on the inner wall temperature, which would emerge long after shooting. The research provided theoretical basis for the safe use of combustible cartridge cases.

Four-legged hunter (FLH) robot: design and shooting control to moving targets with SMC

The design and control of robotic shooting control systems in defense systems is one of the important research topics in recent years. This study focuses on the design, modeling, and success of the shooting control system of the 14 Degrees of Freedom (DoF) Four Legged Hunter Robot (FLH) system with 2 DoFs gun barrel systems. The three-dimensional dynamic model of the FLH-Robot with gun barrel system was created by the Simscape Multibody toolbox of the MATLAB program. The leg joints of FLH were controlled by the PID control method to perform the motion of the robot. Gun barrel stabilization was performed in order to ensure the orientation of the gun barrel system to the predetermined targets and to enhance the hitting success rate. Mechanical oscillations in the robot body were applied as a disruptive effect on the gun barrel system. The sliding-mode control (SMC) method was applied to 2 DOFs gun barrel system. Ballistic simulations were repeated for situations where the targets were fixed and mobile. While the robot was walking, in the first shooting scenario, the shots made on fixed targets placed in random coordinates were hit with a maximum error of 3.3 cm. In the second shooting scenario, shots were fired on moving targets at a speed of 0.1 to 1 rad / s, and hitting success was achieved with a maximum error of 0.387 m. When hit error rates are analyzed, the usability of FLH-Robot for the defense industry was demonstrated.

A model for plasma–neutral fluid interaction and its application to a study of CT formation in a magnetized Marshall gun

A model for plasma/neutral fluid interaction was developed and included in the implementation of non-linear MHD equations to a new code framework. The source rates of ion, electron, and neutral fluid momentum and energy due to ionization and recombination are derived using a simple method that enables the determination of the volumetric rate of thermal energy transfer from electrons to photons and neutral particles in the radiative recombination reaction. This quantity cannot be evaluated with the standard formal procedure of taking moments of the relevant collision operator and has been neglected in other studies. The plasma/neutral fluid interaction model was applied to study compact torus (CT) formation in the Super-Magnetized Ring Test (SMRT) and Spherical Compact Toroid (SPECTOR) magnetized Marshall guns, enabling clarification of the mechanisms behind the significant increases in CT electron density that are routinely observed well after formation on the SPECTOR experiment. Neutral gas, which remains concentrated below the gas valves after CT formation, diffuses up the gun barrel to the CT containment region where it is ionized, leading to the observed electron density increases. This understanding helps account for the exceptionally significant increase in temperature and the markedly reduced density, observed during the electrode edge biasing experiment conducted on SPECTOR. It is thought that edge fueling impediment, a consequence of a biasing-induced transport barrier, is largely responsible for the observed temperature increase and density decrease.

Investigation on mechanical behavior of composite electromagnetic gun barrel based on the high tension winding

In this paper, a design of the non-axisymmetric composite electromagnetic gun barrel is proposed. A finite element model is established to simulate the mechanical behaviors of the composite electromagnetic gun barrel based on equivalent temperature cooling method. In the process of analysis, the effect of fiber tension, curing times and interaction between each composite layer are discussed. The results show that with increase of fiber layers, the fiber tension of inner layer will be released continuous, and the trend also exists between pre-cured layers. When winding layer is 118, the maximum radial displacement of the core is 0.549 mm under the action of electromagnetic repulsion (6MN). And the conclusions can be used as a reference foe design of composite electromagnetic gun barrel.

Micro/Nanocrack Propagation and Fatigue Strength Analysis of Gun Barrel

Micro/nanocrack propagation and fatigue strength have a very important effect on metals used in a wide variety of applications, such as household electrical appliances, automobile engine, aerospace propeller, and munitions. In this paper, to analyze the rule of gun barrel micro/nanocrack propagation and the mechanism of fatigue failure, we simplified the gun as thick-walled pressure vessel, established the barrel fatigue analysis model under the impact force of bore pressure, calculated the transverse/longitudinal micro/nanocrack propagation caused by initial defect point and the corresponding fatigue strength of barrel, which were validated by finite element analysis. The results show that the fatigue danger zone of the barrel mainly distributes in the fore and aft ends of barrel, which affects the micro/nanocrack propagation rate and barrel life. The propagation rate of a longitudinal micro/nanocrack in the radial direction is faster than that of the axial direction, and that of an initial micro/nanocrack in the transverse is slower than a micro/nanocrack in the longitudinal direction. Therefore, the process control of initial defects in the fatigue danger zone, especially the composite strengthening of material properties to control the longitudinal initial micro/nanocracks and to alleviate the radial propagation rate of barrel micro/nanocracks, is the way to improve the fatigue life of the barrel. The model also provides a basis for analyzing the cause and mechanism of barrel bulging.

Study on Engraving Resistance Characteristic of Band Based on Different Structure Parameters of Rifling

The gun barrel working in complex environments is prone to damage, including the wear and ablation of the bore in the gun barrel. These changes cause changes in the rifling structure, which in turn affects the combustion law of gunpowder gas, which affects the pressure in the bore and changes the internal ballistics of the gun performance. This article takes a large caliber howitzer as the research object, considers the frictional force change during high-speed and high-pressure sliding, and also considers the energy conservation criterion during the engraving process. The initial ballistic equations are established during the initial movement period and Coupled solution with band engraving process. Considering the large deformation, high strain rate, temperature softening effect and cumulative damage effect, an explicit dynamic algorithm is used to compare the differences of the elastic band engraving process under different rifling structure parameters. The influence of different rifling structure parameters on the force state of the belt is analyzed. The influence of the main structural parameters of the engraving system on the belt engraving process is obtained. It provides a useful reference for the integrated analysis of the ammunition and the gun and the optimization of the barrel structure.

Influence of Temperature-Dependent Tensile Strength on Gun Barrel Life Prediction

With comprehensive application of the theories of coating shear failure mechanism and fatigue cumulative damage, a life prediction method of a gun barrel is proposed based on the shear fatigue damage accumulation at the coating-substrate interface. The life of a small-caliber gun barrel is predicted by use of constant tensile strength at normal temperature and temperature-dependent tensile strength, respectively. The influence of the two kinds of tensile strength on barrel life prediction results is analyzed. Life test proves that the prediction method proposed here is credible and practical. The research results show that the reduction of interface tensile strength due to temperature rise in the firing process is an important inducement of interface damage and gun barrel failure. When the temperature-dependent tensile strength is considered in life prediction model, the prediction results are smaller than that predicted by use of constant tensile strength and well matched with the life test results. Therefore, the temperature-dependent tensile strength should be incorporated in the model of gun barrel life prediction.

Sensitivity analysis of radial defect detection of gun barrel based on ultrasonic guided wave

In this paper, aiming at the low efficiency of defect detection of weapon equipment, ultrasonic guided wave non-destructive testing technology is proposed to detect the radial wear defects in gun barrel which have a great impact on its combat effectiveness. At the same time, the sensitivity of different modes of L0,2 and t0,1 ultrasonic guided waves to the detection of such defects is analyzed in this paper, so as to provide theoretical guidance for the mode selection of ultrasonic guided waves in the next practical detection of gun barrel.

Mechanical properties of steel gun barrel processed by cold radial forging with stepped mandrel under different forgingratios

Mechanical properties of 30SiMn2MoVA steel gun barrel processed by cold radial forging with stepped mandrel under the different forging ratios were investigated in the present work. This work mainly reported the axial and circumferential mechanical properties of forged gun barrel before and after annealing. The axial and circumferential mechanical properties were measured by tensile test and bulging test, respectively. The results suggested that the strength was enhanced and elongation was decreased by forging which was caused by cold work hardening. After annealing, the anisotropy of elongation was observed. The circumferential elongation was weaker than the axial. With the increasing of forging ratios, strength anisotropy was exacerbated gradually. The circumferential strength was inferior to the axial. Besides, there were axial penetrating cracks in the failure state of circumferential bulging test specimens. Through the electron microscopic examination, the axial micro cracks and wrinkles in the inner wall of the forged tubes were observed. It showed that the cold radial forging with stepped mandrel may result in the defect in the inner surface of the gun barrel which should be paid attention.

Finite element analysis of the friction and wear of the barrel bore during the projectile extrusion

The size change of the forcing cone directly affects the ballistic performance of the gun and the life of the gun barrel. In order to study the force law and wear law of the forcing cone during the continuous engraving process of the projectile, which established a refined finite element model of the projectile-barrel interaction. The model contains rifling finite element mesh grid with process chamfer. Based on the established transient coupled thermo-mechanical finite element (FE) model of the projectile-barrel interaction, the effects of the temperature and pressure of the gunpowder gas, the friction coefficient between the rotating band and the forcing cone were comprehensively considered. Combined with the Archard wear model, numerical method are used to obtain the stress law of the forcing cone and the amount of wear due to friction in the continuous engraving process of the projectile. The research content in this article can provide some guidance for predicting the life of the tube.

Research on muzzle response characteristics of automatic gun on launching based on rigid-flexible coupling dynamics

In order to study the important influence for firing dispersion of muzzle response of automatic gun on launching, the rigid-flexible coupling dynamics model of automatic gun was established based on the rigid-flexible coupling system dynamics theory in software RecurDyn. And the flexible body of gun barrel assembly was set up by the modal synthesis method of dynamic sub-structure. The Hertz contact theory and flexible Bushing forces model were made equivalent to these constrained joints. According to the characteristic of automatic gun structure and continuous launching load, the dynamic vibrating response of simulation and analysis was made for the automatic gun on launching. The muzzle vibration response displacements in vertical and horizontal direction were obtained in the 300 rate of fire. Then the muzzle vibration velocity and acceleration with different structure clearance were also calculated by the finite element analysis program of the rigid-flexible coupling dynamics model of automatic gun. Through the comparison and analysis, the numerical solutions are closely matched with the experimental results. The results show that the vertical angle error of firing dispersion is less than 3.8% and the horizontal angle error is less than 10.2%. Thus, the simulation and experimental results verify the correctness and feasibility of this model. Further the structure design and optimization of automatic gun can be provided a reference foundation.

MICROSTRUCTURAL, THERMAL AND WEAR BEHAVIOR OF YSZ/Al2O3 THERMAL BARRIER COATINGS FOR GUN BARREL APPLICATIONS

The present study aims to investigate the performance of Yttria Stabilized Zirconia and Alumina Thermal Barrier Coatings deposited on EN steel substrates used in gun barrel through Atmospheric Plasma Spray Process. Chemical compositions of the EN steels (EN8, EN19, EN24 and EN36C) as well as the particles were examined prior to the coating process. Atmospheric Plasma Spray Process was carried out using carrier gas with two different flow rates of 3 and 4scfh. A bond coat was made for 50 µm by depositing NiCrAlY and the top coats were made for 200 µm distinctly using Yttria Stabilized Zirconia and Alumina. X-ray Diffraction and Field Emission Scanning Electron Microscope examination were performed on the coated specimens to observe the phase and morphology respectively. Thermal testing and Infrared thermal imaging were performed to measure the insulation performance and spallation performance under different exposure time (upto 20 minutes) for the input temperature of 200˚C. Wear and scratch test were conducted on the specimens to determine the coating integrity as well as bonding of top and bond coat to substrate. YSZ coated EN36C steel produced under carrier gas flow rate of 3scfh possessed greater insulation performance compared to all other steels. Also, YSZ coated EN36C steel has better wear and scratch resistance indicating lesser deformation compared to other materials.

Results of Wear Evident in the Gun Barrel Bore of the Leopard 2A4 Main Battle Tank

Dynamic Testing Centre of Military Institute of Armament Technology (MIAT, Zielonka, Poland) runs dynamic tests and research for many years. Tests are conducted for armament industry, Polish Army and for scientific purposes. The influence of construction, exploitation, technology factors for 120 mm Rh-120 L44 durability is one of the area of interest of MIAT. 120 mm Rh-120 L44 cannon is a primary weapon of Leopard 2A4 and 2A5 tanks. These tanks in total number of 247 (142 - Leopard 2A4 and 105 Leopard 2A5) are in use of Polish Army since 2002. In the paper analysis of Leopard 2A4 L44 cannon barrel’s bore wearing out using Polish and foreign production ammunition was presented. The analysis was made basing on document TDv18 which is specifying the conditions affecting on taking out of a service decision. These conditions are: boundary of wearing out barrel material and specifying the number of shoots after exceeding, the fatigue of material will achieve critical value.

Effect of Magnetically Confined Plasma on the Fatigue Life of a Thick-Walled Cylinder

As the inner wall pressure increases during gun shooting, the fatigue life of a gun barrel is reduced. This article proposed a method based on magnetically confined plasma theory to increase the fatigue life of a gun barrel. The core idea was to reduce the pressure on the inner wall of the gun barrel by restraining the movement of plasma inside it via the solenoid magnetic field. As a result, its fatigue life improved. The confinement mechanism of the solenoid magnetic field on plasma was first analyzed. The influence of different magnetic field strengths on plasma was studied through simulation modeling. The law of magnetically confined plasma in the gun barrel was obtained. Second, the inner wall pressure was tested after a solenoid magnetic field was added to the gun barrel. The effectiveness of the proposed method in reducing pressure on the inner wall of the gun barrel was verified. The electromagnetic interference introduced by high-power electrical appliances and solenoid magnetic field in the test was effectively reduced by adopting multistage electromagnetic shielding protection. A Manson–Coffin model was also used to evaluate the fatigue life of the gun barrel, and the results verified the feasibility of the proposed method for improving its fatigue life.

Tribological characteristics of high strength low alloy steel under various environmental conditions

High strength low alloy steel has excellent heat resistance and high strength. As it is commonly used as gun barrel material, a long service life and superior wear resistance are necessary for steel components. Here we investigated the wear characteristics of high strength low alloy steel surfaces under various environmental conditions, using a pin-on-disk wear test. Oxidation and wear debris effects on the coefficient of friction (COF) of the alloy steel were examined under air and argon (Ar) gas flow at atmospheric conditions.

Damage and fracture of gun barrel under wear-fatigue interaction

Gun, projectile and propellant are three fundamental components of a launching system. Generally, a barrel has to be condemned after a number of rounds have been fired. During the total useful life of gun barrel, it bears severe damage induced from erosion by high pressure and high temperature propellant combustion gas, and wear due to high speed friction between projectile and gun bore. Meanwhile, the gun barrel undergoes a dynamic loading of gas pressure, mechanical stress and thermal stress when firing a round. Thousands of firing cycles lead to gun barrel fatigue. Interaction of wear, including erosion, and fatigue damages the gun barrel and eventually the gun will become inaccurate because of wearing away gun bore materials. However, a gun barrel will fracture in a sudden manner because of fatigue. It is found that microcracks form on the bore surface after only a few rounds have been fired, which lays the foundation for growth and propagation of cracks under fatigue loading. In this paper, laboratory hydraulic fatigue tests were carried out on a tube with pre-machined crack on its inner surface by using an MTS 809. Strain gauges were adhered to the outer surface of the tube to monitor strain during testing process. The hydraulic oil pressure was measured by a pressure sensor. The experimental results show that there are three stages of outer surface strain variation, namely stable increase, fast increase and abrupt increase, which corresponds to the history of crack evolution. Crack grew stably in the initial stage under cycle of loading and a major crack is gradually formed. When the major crack size reaches a certain value, the propagation velocity of crack is accelerated fast and the critical size is reached in a short time. Eventually the tube fractured suddenly. The experimental findings will help us to gain new insight into the physical mechanism of fatigue and fracture of gun barrel and provide a possible method to evaluate health of gun barrel in service.

Experimental study on initial ballistic characteristics of cased telescoped ammunition

There is a loading process after the projectile of the cased telescoped ammunition (CTA) fired in the chamber, which has important influence on the stability of interior ballistics, the firing accuracy and the gun barrel life. In order to study the characteristics of velocity and attitude in the initial motion of the projectile of the CTA, a special projectile for the initial ballistic test was designed, and an initial ballistic test system based on the high-speed camera was built. The loading process after firing was observed and the loading velocity was measured. The results show that the loading speed of the projectile is about 30m/s. The initial ballistic parameters of the projectile can be studied quantitatively and the motion attitude of the projectile can be examined qualitatively by using the initial ballistic test system based on the high-speed photography.

Simulation analysis of residual stress of autofrettaged barrel under multi-field coupling loads

High-pressure guns repeatedly withstand transient high pressures and high temperatures, which have a great influence on the residual stress of the barrel. In order to study the stress distribution of autofrettaged barrel under multi-field coupling during launch, the mechanical autofrettage gun barrel and finishing process of the barrel was simulated by ANSYS finite element software, in which the finite element model considering the initial residual stress of the autofrettaged barrel was established, and the dynamic and static continuous process simulation of the barrel was carried out. On the basis of obtaining the residual stress distribution, an analytical model under the coupling of transient pressure field and temperature field is established. The APDL language programming is used to calculate the time and space distribution of the stress of the key parts of the barrel. A phenomenon is found that the equivalent stress on the outer surface of the barrel increases sharply with the increase of the pressure, and then rises to the highest point with the temperature of the barrel. After the fire process, the equivalent stress slowly recovers with the decrease of the temperature. The law of external surface stress rise in the fire period is a step process. It provides a theoretical basis for studying the residual stress release law the safety design of barrel.