Gun Barrel Research Articles

Numerical Calculation and Uncertain Optimization of Energy Conversion in Interior Ballistics Stage

Gun firing is a process that converts propellant chemical energy to projectile kinetic energy and other kinds of energies. In order to explore the energy conversion process, firstly, the interior ballistics mathematical model and the barrel-projectile finite element model are built and solved. Then, the related variable values and energy values are obtained and discussed. Finally, for improving energy efficiency, the interval uncertainty optimization problem is modeled, and then solved using the two-layer nested optimization strategy and back-propagation (BP) neural network surrogate model. Calculation results show that, after optimization, the heat efficiency raises from 31.13% to 33.05% and the max rifling stress decreases from 893.68 to 859.76 Mpa, which would improve the firing performance and prolong the lifetime of the gun barrel.

Study on the Simulation of Electromagnetic Squint

This paper introduces the simulation electromagnetic gun device based on STM32, which mainly uses openmv and laser ranging module as recognition sensor. The system obtains the target position through openmv, uses PID algorithm to control the steering gear with two degrees of freedom to make the gun barrel aim at the target, then obtains the target distance through the laser ranging module, obtains the target and controls the energy storage capacitor voltage of the electromagnetic gun, increases the voltage through the DC power supply, charges and discharges the capacitor through the thyristor controlled by the relay, the capacitor discharge generates the magnetic field through the coil, and generates the magnetic field inside the steel ball Instead, a magnetic field ejects the ball. This design realizes the closed-loop control of the capacitor voltage to ensure the stability of the projectile exit velocity. The system is stable in operation and has high precision.

Micro-particles spraying via non-stationary flame acceleration process

Thermal spraying techniques are widely used for aerospace applications allowing improve significantly thermal and electrical insulating properties and strength of structural materials. Over the past decades, detonation thermal spraying technology has established itself as a reliable and efficient approach for the deposition of a great variety of functional coatings actively used in the spacecraft industry. In the present paper, various aspects of the physical processes intrinsic for detonation spray are analyzed numerically. In particular, non-stationary processes of the flame development in the detonation gun barrel are considered in conjunction with the dynamics of the suspended microparticles. The benefits of tilted substrate orientation and incomplete barrel filling are studied and interpreted based on the analysis of gas-dynamical flows. Developed flow patterns are analyzed for the case without successful detonation initiation inside the barrel that allowed determining the effects of detonation gun barrel length, mixture reactivity, and inertia of particles. In particular, it is obtained that the parameters and distribution of the suspended phase can be optimized, taking into account the peculiarities of the carrying gas flows that emerged inside the detonation gun barrel to provide greater spraying efficiency.

Internal Versus External Cracking—Their Impact on the Fatigue Life of Modern Smoothbore Autofrettaged Tank Gun Barrels

Abstract An extensive analysis of the fatigue life of a typical modern autofrettaged smoothbore tank barrel, cracked either internally or externally, in terms of the initial crack depth and shape, type and level of autofrettage, was conducted. Five overstraining cases were considered: no-autofrettage, 70% and 100% hydraulic autofrettage, and 70% and 100% swage autofrettage. KINmax, the maximum combined stress intensity factor (SIF) KINmax = (KIP + KIA) max, due to both internal pressure and autofrettage, as a function of crack depth for a large number of internal and external crack configurations was determined by the finite element method (FEM). A novel realistic experimentally based autofrettage model, incorporating the Bauschinger effect, was integrated into the finite element model, replicating both the hydraulic and swage autofrettage residual stress fields (RSFs) accurately. Fatigue lives were evaluated by integrating Paris' Law using the above values of KINmax. The following conclusions can be drawn from the results: hydraulic and swage autofrettage have a dramatic beneficial effect in extending the fatigue life of an overstrained barrel 4–11 times as compared to an identical nonautofrettaged tube. The fatigue life of overstrained barrels is controlled by internal cracking, for barrels overstrained by up to ε = 100% hydraulic autofrettage, by up to ε = 70% in the case of swage autofrettage, and by external cracking for ε = 100% swage autofrettaged. Eliminating or carefully designing stress concentrators on the tube's external face and keeping away from corrosive agents thus, extending the fatigue-crack initiation life of an external crack, enables the increase of the level of swage autofrettage to up to ε = 100%. Swage autofrettage is much more superior to hydraulic autofrettage. The fatigue life of a 70% swaged autofrettaged barrel is 1.5 times higher than that of a 100% hydraulically autofrettaged tube. If full swage autofrettage is permissible, the fatigue life of such a barrel is twofold that of a fully hydraulically autofrettaged tube. Unlike the commonly accepted concept, the level of hydraulic autofrettage should not be limited to 70%, and full hydraulic autofrettage should be used. Similarly, in the case of swage autofrettage, if the detrimental effect of external cracking is removed by proper design and maintenance of the tube's outer surface, the level of autofrettage can be increased to up to ε = 100%, thus, gaining an increase of 33% in the fatigue life as compared to overstraining the barrel to only ε = 70%. Initial crack depth and shape are major factors affecting the fatigue life of the barrel. The deeper the initial crack depth, a0, and the slenderer its shape, a/c→ 0, the shorter the fatigue life of the barrel.

Calibration and precise orientation determination of a gun barrel for agriculture and forestry work using a high-precision total station

To meet the agricultural and forestry needs of humans, the introduction and use of modern technologies with high precision and applicability in the field of agro-forestry is inevitable. Moreover, the accuracy of currently used instruments and techniques is undergoing constant improvement to yield better results. The effectiveness of the gun barrel for agro-forestry has been compromised by its low precision and high cost for many decades. This study aimed to develop a new method to increase the accuracy of the gun barrel by integrating the absolute fixed-point orientation and adjustable gun barrel calibration profile using a total station for precise determination. For this purpose, the reunification of the measurement of an absolute coordinate system by total station resection with the aid of two or more known control points was carried out. Then, through barrel calibration, a fixed measurement target was set on the barrel and a fixed spatial position relationship between the measurement target and the axis of the barrel was established. After that, the orientation of the barrel was adjusted, and the three-dimensional coordinates of the fixed target were measured using a total station instrument. The barrel simulation test results showed that the total station has a good accuracy in the calculation of azimuth angle and elevation angle, while the measurement error could be guaranteed within 0.2 mil. Our newly proposed method has satisfied the accuracy test requirements and shown higher accuracy than other related conventional methods. It will make the gun barrel more useful and will enhance its applicability in the field of agro-forestry.

Radiodense bullet wipe around osseous entrance gunshot wounds.

"Bullet wipe" is the material deposited by a bullet on any surface with which it comes into contact after it is fired and may contain debris from the gun barrel, including particles of primer and metal fragments from previously fired bullets. X-ray analysis is a non-destructive method by which traces of metallic elements can be visually detected. The analysis of osseous defects for radiodense bullet wipe (RBW) assists in determining the presence or absence of perforating gunshot wounds, especially in fragmented, skeletonized remains. The aim of our current study was to determine the frequency of RBW around entrance firearms injuries that perforated bone. We prospectively analyzed entrance gunshot wounds for RBW over a three-year period using digital X-ray analysis (n=59). We retrospectively reviewed the corresponding autopsy reports to determine the frequency of RBW by biologic sex, reported ancestry, age-at-death, location of wound, manner of death, range of fire, bullet caliber, and presence of bullet jacket. Data were analyzed by Fisher's exact test or Chi-square test with significance levels accepted at p<0.05. RBW was present in 66% (n=39) of examined cases. Decedent characteristics did not significantly alter RBW distribution, including biologic sex (p=0.75), reported ancestry (p=0.49), and age-at-death (p=0.43). Additionally, the location of the osseous entrance gunshot wound, manner of death, range of fire, and cartridge caliber did not affect RBW detection. All cases involving non-jacketed rounds (n=5) showed RBW (p=0.30). To our knowledge, this study is the first to report the frequency of RBW detection from osseous entrance gunshot wounds.

Vibration characteristics of Timoshenko stepped beam under moving load considering inertial effect

The vibration of gun barrels would result in the change of impact point, which would further reduce the firing accuracy of weapons. In the past, the calculation model based on the Euler beam theory could not satisfy the accuracy requirements. Based on the Timoshenko beam theory, the vibration equation of the stepped beam is established by invoking continuum transfer matrix method. The forced vibration of the stepped beam under the inertial moving load is solved. The model has better precision than the Euler beam model. The endpoint of the cantilever beam is analyzed. It is shown that the endpoint response increases with the increasing mass and acceleration of moving load, so does the inertial coefficient. With the increase of moving load speed, the endpoint response decreases, and the inertia coefficient increases. Among the three parameters, the mass of moving load is the main factor affecting the inertia coefficient. Furthermore, both free and forced vibrations of other stepped beam shaped structures with arbitrary segments and boundary conditions can be explored by using the proposed method.

The microstructure, texture evolution and plasticity anisotropy of 30SiMn2MoVA high strength alloy steel tube processed by cold radial forging

Cold radial forging is an efficient and high-precision process for producing rotary parts such as axles and gun barrels, etc. 30SiMn2MoVA high strength alloy steel is a kind of fine pearlite steel usually used for moulds and barrels. This work focused on the effect of the cold radial forging on the microstructure, texture evolution and plasticity anisotropy of forged steel tube under different forging reductions. The results suggest that most banded structures that are parallel to the axial direction are developed by the radial forging process. The grains are elongated and refined after forging. The increase of dislocation density with the increase of deformation is the reason for grain refinement. Refined grains and high dislocation lead to high strength. Meanwhile, anisotropy was obvious and was exacerbated by the growth of the forging deformation. The circumferential strength and elongation are inferior to the axial. With the increasing of forging ratios, the α-fiber texture is well developed. The relationship between the volume fraction of texture and plastic strain was built. It can predict the volume fractions of the main texture components in the cold radial forged 30SiMn2MoVA steel tube. The Taylor factors of the main orientations were calculated. The {111}<011>(γ-fiber), {110}<110>, {111}<110>(α-fiber), {114}<110>, {112}<110> and {223}<110> texture components help to enhance the axial yield strength. Comparing the ratio of the axial average Taylor factor and the circumferential average Taylor factor with the yield strength ratio, it is found that yield strength anisotropy is not well predicted only taking into account the crystal texture. The effect of banded structures on the strength should also be considered.

A Study on the Reliability Improvement for Assurance Pressure of Tank Gun Barrel

A Study on the Reliability Improvement for Assurance Pressure of Tank Gun Barrel

Development of multi-physics numerical simulation model to investigate thermo-mechanical fatigue crack propagation in an autofrettaged gun barrel

In this research, a detailed multi-physics study has been carried out by numerically simulating a solid fractured gun barrel for 20 thermo-mechanical cycles. The numerical model is based on thermal effects, mechanical stress fields and fatigue crack mechanics. Elastic-plastic material data of modified AISI 4340 at temperatures ranging from 25 to 1200 °C and at strain rates of 4, 16, 32 and 48 s−1 was acquired from high-temperature compression tests. This was used as material property data in the simulation model. The boundary conditions applied are kept similar to the working gun barrel during continuous firing. A methodology has been provided to define thermo-mechanically active surface-to-surface type interface between the crack faces for a better approximation of stresses at the crack tip. Comparison of results from non-autofrettaged and autofrettaged simulation models provide useful information about the evolution of strains and stresses in the barrel at different points under combined thermo-mechanical loading cycles in both cases. The effect of thermal fatigue under already induced compressive yield due to autofrettage and the progressive degradation of the accumulated stresses due to thermo-mechanical cyclic loads on the internal surface of the gun barrel (mimicking the continuous firing scenario) has been analyzed. Comparison between energy release rate at tips of varying crack lengths due to cyclic thermo-mechanical loading in the non-autofrettaged and autofrettaged gun has been carried out.

Detonation spraying of Ti-Cu mixtures in different atmospheres: Carbon, nitrogen and oxygen uptake by the powders

The phase composition and microstructure of coatings formed by detonation spraying of Ti-Cu powder mixtures using C2H2 + kO2 explosive charges with k varying from 0.7 to 2.0 were studied. The Ti-Cu system was selected to demonstrate the possibilities of forming metal matrix composites (MMCs) with in-situ synthesized ceramic particles during the coating deposition. The formation of composite microstructures needs to be considered when obtaining carbon-containing MMCs by detonation spraying using acetylene-oxygen mixtures at k ˂ 1. The focus of the present study is the phase formation, microstructure development and hardness variation of the coatings caused by carbon, oxygen and nitrogen uptake by the Ti-Cu mixtures during spraying. Carbon released in the form of graphene nanoplatelets as a result of incomplete combustion of acetylene at k = 0.7 reacted with titanium, and, in the presence of nitrogen (a carrier gas), the TiCxNy phase formed in the coatings. Copper was found to play a protective role, reducing the conversion degree of titanium into the ceramic phases. Deposits containing 21 – 44 wt.% of ceramic components formed when an explosive charge equal to 50% of the gun barrel volume was used, the nature and concentration of the ceramic phases depending on k. At k = 2.0 and an explosive charge of 50%, a composite coating reinforced with Ti2O3, TiO and TiN (comprising 41 wt.% in total) was obtained. This composite showed a microhardness of 480 HV, which was due to a high content of ceramic phases synthesized in situ during spraying.

Simulation analysis of autofretted barrel strength based on ABAQUS

Autofretted technology is used generally by high-pressure guns to enhance the strength of barrels. Mechanical properties of the autofretted barrel were studied based on the finite element software ABAQUS. For the open autofretted process, a simulation model of gun barrel was established and its accuracy was verified by comparing the simulation results with theoretical results. Various stress of autofretted gun in the firing process was simulated, and the best autofretted pressure was found. For the closed autofretted process, autofretted pressure was affected by the gap amount between the mold and the barrel.

ISOTHERMAL OXIDATION BEHAVIOR AND THERMAL SHOCK RESISTANCE OF THREE-KIND Cr COATINGS ON PCrNi3MoVA STEEL

Isothermal oxidation behavior at 900 °C for 5 h and thermal shock resistance at 900 °C of three-kind Cr coatings prepared by electroplating, magnetron sputtering and multi arc ion plating technologies on PCrNi3MoVA steel were investigated. Micromorphologies of three-kind Cr coatings before and after tests were observed by the scanning electron microscopy and crystallization phase identification was studied by the X-ray diffraction. Oxidation of three-kind Cr coatings showed characteristic morphologies of electroplating Cr coating with microcrack, magnetron sputtering Cr coating with columnar crystal and multi arc ion plating Cr coating with microdroplet during coating preparation were main reasons for different properties. Correspondingly, the failure mechanisms of delamination, through spalling caused by through cracks and through spalling caused by surface spalling of droplet were obtained by thermal shock test. The results indicate that multi arc ion plating, for its property of high temperature resistance, could be a more effective approach to prolong gun barrel life.

Development of a geometric model of a new method for delivering extinguishing substances to a distant fire zone

A geometric model of a new method of delivering fire-extinguishing substances to a fire zone located at a considerable distance was offered. The idea of delivery is based on the mechanical action of throwing. To this end, a substance (e.g. extinguishing powder) is loaded in a hard shell made as a special container. After delivery by means of a launcher to a fire zone, the container has to release the substance which will promote fire extinguishing. The known method of remote delivery of extinguishing substances uses a pneumatic gun with a cylindrical container. During delivery, the cylinder must rotate around its axis to ensure flight stability. The cylinder is rotated by a special turbine when passing through the gun barrel. There are difficulties in regulating the distribution of compressed air flows during the turbine operation. In addition, the tightness of the pneumatic part of the gun should be monitored. The new delivery method uses a container in a form of two spaced loads similar to a sports dumbbell. The dumbbell motion is initiated by simultaneous action of explosion-generated pulses directed at each of its loads in a pre-calculated manner. This results in the rotational motion of the container. To describe the dynamics of the dumbbell motion, a Lagrangian was defined and a system of Lagrange differential equations of the second kind was set up and solved. Examples of modeling trajectories of the centers of masses of the dumbbell loads taking into account air resistance were given. The proposed method is planned to be a basis of a new fire extinguishing technology. This is evidenced by the new scheme of launching the dumbbell by means of explosion-generated pulses of charges of two pyro cartridges. The obtained results make it possible to estimate magnitudes of explosion-generated pulses necessary for throwing and corresponding distances of the dumbbell delivery

A Study on Puncture Resistance of Composite Metal Foam Core Sandwich Panels

Steel–steel composite metal foam‐core sandwich panels (S‐S CMF‐CSP) with variety of thicknesses of components (face sheets and cores) are manufactured by attaching stainless steel face sheets to a S‐S CMF core using either solid‐state diffusion bonding or adhesion bonding. Scanning electron microscope imaging is used to evaluate the microstructure of diffusion bonded panels particularly at the interface of the core and face sheets. The puncture resistance of the sandwich panels is evaluated using a 0.50 caliber Mann gun barrel, modified to fire 2.54 and 3.175 cm diameter steel balls creating kinetic puncture energies up to 14 500 J. But, no complete penetrations through any of the sandwich panels are achieved. At lower impact velocities, tensile stresses resulted from the sudden changes in mechanical impedance between various layers of the sandwich panel recoil the ball back while at higher impact velocities, the high strain rate deformation at the point of impact along with the friction heat between the ball and panel surface fuses the ball to the target instantly resulting in debonding of adhesively bonded panels, whereas the diffusion bonded panels resist better. Sandwich panels with higher areal densities and thicker face sheets did not show major advantages over the panels with thinner face sheets.

Experimental Study of Mechanical Properties of 30SiMn2MoVA Steel Gun Barrel Processed by Cold Radial Forging

Abstract This work focused on the mechanical properties of 30SiMn2MoVA high strength steel gun barrel processed by cold radial forging. Three states of the tube made of this material (the state without forging, the as-forged state without annealing, and the as-forged state with annealing) were chosen to compare the axial and circumferential mechanical properties. As a result, anisotropy was found at as-forged state. The circumferential mechanical properties were inferior to the axial. The circumferential yield and tensile strength were about 150 MPa lower than the axial after forging, and the axial elongation was 155% higher than the circumferential. Even after annealing, the circumferential elongation cannot be restored to the same level as the state without forging. The reasons for anisotropy were investigated by the microstructure. The banded structure along the axial direction was observed in the forged barrel. Meanwhile, the crystalline grains of the forged gun barrel had the highest intensity of {111}〈110〉 texture which meant the grains had obvious preferential orientation. The relationship between crystallographic texture and yield strength was analyzed based on the Schmid factor. Additionally, the elastic limit internal pressure of anisotropic gun barrel was calculated, and it was lower than that under isotropic condition.

Numerical reconstruction of a non-smooth heat flux in the inverse radial heat conduction problem

When gun barrels are multiple fired, monitoring the non-smooth heat flux of the gun with the additional input data makes it possible to identify the corrosion of the gun. Based on this background, we study the identification of the non-smooth heat flux in a 1-dimensional heat transfer system. Aiming to overcome the non-smoothness of the unknown heat flux and to simplify the choice of regularization parameter, we transform the inverse problem to a constraint optimization problem and prove the existence and convergence properties of the regularization solution. Then an algorithm based on minimizing the data-match term and penalty term alternatively is proposed. Finally, a numerical experiment supports our regularization scheme quantitatively, especially for input data with high noise level.

Cutting of tantalum: Why it is so difficult and what can be done about it

Tantalum has long drawn the ire of machinist, being particularly difficult to cut. Often referred to as being ‘gummy,’ cutting of tantalum is characterized by very thick chips, large cutting forces, and a poor surface finish on the machined surface. These unfavorable attributes of the cutting have usually been attributed to bcc tantalum's high strain-hardening capacity, relative softness, and low thermal conductivity; and a small shear plane angle. Here, we show using in situ high-speed imaging at low speeds, and ex situ chip morphology observations at higher commercial cutting speeds (625 mm/s), that the gummy nature of Ta in cutting, including the large forces and thick chips, is actually due to the prevalence of a highly unsteady plastic flow – sinuous flow – characterized by large-amplitude folding and extensive redundant deformation. The sinuous flow and the associated folding are much more amplified and extreme in tantalum (chip thickness ratio, 30–50), and with different morphology, than that observed in fcc Cu and Al (chip thickness ratio, 10–20), wherein this flow mode was first uncovered. The in situ observations are reinforced by force measurements, and chip morphology and cut-surface characterization. The observations also suggest that the sinuous flow, in the same genre of unsteady mesoscale flow modes such as shear banding and segmented flow, is quite prevalent in cutting of highly strain-hardening metal alloys.By application of a surface-adsorbing (SA) medium, e.g., permanent marker ink, to the initial workpiece surface, we show that sinuous flow can be disrupted and replaced by a more energetically favorable flow mode – segmented flow – with thin chips and >70% reduction in the cutting force. This flow disruption is mediated by a local ductile-to-brittle transition in the deformation zone, due to the action of the SA medium – a mechanochemical (MC) effect in large-strain deformation of metals. Equally importantly, the MC effect and underlying segmented flow are beneficial also for machined surface quality – producing nearly an order of magnitude improvement in the surface finish, creating a surface with minimal residual plastic strain, and reducing level of material pull-out. Thus, by use of the SA medium and triggering the MC effect, a promising new opportunity is demonstrated for improving the machinability of Ta by ameliorating its gumminess. The results could enhance the viability of Ta for applications such as gun barrel liners – applications for which it has been hitherto considered but discarded due to its poor machining characteristics.

Performance analysis of coaxial thermocouples for heat flux measurement of an aerodynamic model on shock tube facility

The K, E and J-types of coaxial thermo-sensors have been used to measure surface heat flux at the nose, spatial position-1 and spatial position-2 over an aerodynamic model subjected to a homemade shock tube flow facility. The high pressure shock has been applied to the aerodynamic model for 60 ms subsequently their variation in transient temperatures have been recorded for four experimental shots. The surface heat flux has been predicted from the transient temperatures by using one-dimensional heat transfer theory in a semi-infinite solid body. The average errors have been found between four experiments for transient temperature and surface heat flux are less than ±0.2% and ±4% respectively. A two-dimensional numerical model has been developed by using commercial software Ansys to solve the high enthalpy flow facility as exists in shock tube arrangement to validate the experimental results. The accuracy found in transient temperatures and surface heat fluxes are ±0.51% and ±0.633%. These coaxial thermo-sensors will help the design and development of aerodynamic vehicles in terms of measurement of heating rate on different inclined surfaces, missile nose, hypersonic aircraft technology, gun barrel test, advanced production technology, engine measurements etc.

Shooting Control Application from a Quadruped Robot with a Weapon System via Sliding mode Control Method

With the developing technological process, it is expected that the usage of robots will increase in defense systems as in every field. One of the main objectives of the robotic studies for the defense industry is to capture the targeted success under all kinds of disruptive effects with robotic systems and to present this technology to the service of the army. A weapon system with a single degree of freedom was placed on a quadruped robot. System’s dynamic behavior, which has 12 degrees of freedom and planar movements, is modeled mathematically. Simulations of the shots made to the fixed targets were carried out during the walking of the quadruped robot. The gun barrel stabilization was realized to achieve accurate shots under disruptive effects. The sliding-mode control method was used to perform the barrel stabilisation. In this study, it is shown that a quadruped robot with a weapon system can perform successful shots against fixed targets. MATLAB is used for simulations and the results are shown with figures, graphics, and tables.