Projectile Angle Research Articles

Effects of Lateral Flows on the Supercavitation and Hydrodynamic Characteristics of Underwater Series and Parallel High-Speed Projectiles

In this paper, the supercavitation of the parallel and tandem projectiles moving underwater with high-speed under the condition with/without lateral flows is numerically simulated by the volume of fraction (VOF) model. The motion of the projectiles was handled by the overlapping grid and six degrees of freedom (DOF) techniques. The supercavitation evolution and the hydrodynamic characteristics of the projectiles were analyzed for the parallel and tandem projectiles under different conditions. The results show that the cavity shape is symmetrical under the condition without lateral flows, but is no longer symmetrical under the conditions with lateral flows. The asymmetry of the cavity contour increases with the velocity of the lateral flow. For the parallel projectiles, the change trends of the axial velocity of projectile 1 and projectile 2 are nearly the same. The offset velocity of projectile 1 and projectile 2 increases with the increase in the velocity of the lateral flow. The deflection angle of projectile 1 decreases with the increase in the lateral flow velocity but that of projectile 2 increases with the increase in the lateral flow velocity. At t = 3.0 ms, the deflection angle of projectile 2 is up to 20° under the condition of the lateral flow velocity of 11.25%, while the deflection angle of projectile 1 and 2 under other conditions is in the range of 5°. For the tandem projectiles, the axial velocity of projectile 1 gradually decreases. The change trend of the axial velocity of projectile 2 at first is the same as that of projectile 1, and then the change is dependent on the velocity of the lateral flow. Under the condition of the lateral flow velocity with 11.25%Vp, projectile 2 cannot enter the cavity of the front projectile. The change trend of the axial velocity of projectile 2 is similar as but somewhat slower than that of projectile 1. For the parallel projectiles, the ballistic stability of the projectile on the oncoming side is better than that of the projectile on the backflow side. Whether parallel or tandem projectiles, the ballistic stability of projectile 2 becomes worse with the increase in the lateral flow velocity.

A Target Damage Assessment Mathematical Model and Calculation Method Based on the Intersection of Warhead Fragment and Target Mechanism

This paper proposes a target damage calculation method based on the profit-loss value of a warhead fragment group. The group is discretized into a fan-shaped column warhead fragment dispersion arrangement model, and the angle of its intersection with the target is combined to establish the dynamic dispersion density model of the warhead fragment group. In addition, the function to calculate the number of warhead fragments hitting the target’s surface is devised. The capability matrix of the warhead fragment group is constructed according to the quality, quantity, and storage velocity of the warhead fragments, and then, the profit-loss value of the warhead fragment group is established. Combining the intersection probability of the target and the warhead fragment of the dispersion area, the model to calculate the probability of damage caused to the target by the warhead fragment group formation is deduced. The calculation and experimental analysis verifies that the dispersion angle of warhead fragments, the intersection angle of projectile and target, and the intersection distance of projectile and target significantly influence the impact of target damage.

Investigation of impact performance of perforated plates and effects of the perforation arrangement and shape on failure mode

Searching for lighter protective structure and better energy absorption material is the key goal to improve the protection performance of moving platforms. The impact performance of perforated structures subjected to projectile impact and effects of the perforation arrangement and shape on failure mode are investigated experimentally and numerically. Three different impact velocities, three kinds of hole patterns (circle, triangle and square) and two types of hole arrangements (matrix type and dislocation type) of the perforated plate specimens are discussed in this research. The Mie-Grüneisen equation of states and Johnson-Cook strain-rate sensitive material models are selected in the numerical model. The numerical results agree well with the experimental results. The results show that when the impact velocity, hole shape and hole arrangement are different, the failure modes of perforated plate and witness plate can be divided into eight and four modes, respectively. The projectile deflection effects are observed when the projectile passes through the perforated plate. The deviation angle of projectile decreases with the increase of impact velocity. The deviation angle of perforated plate with circle hole and triangle hole by dislocation type is greater than that by matrix type at the same impact velocity, but the conclusion of perforated plate with square hole is just the opposite. The ballistic deflection effect of the perforated structure with triangular hole is greater than that with the circular hole and square hole. The results obtained from the study will provide a reference to the research of new spatial or layered armor systems containing the perforated plates.

ANALYSIS OF THE EFFECT OF PROJECTILE IMPACT ANGLE ON THE PUNCTURE OF A STEEL PLATE USING THE FINITE ELEMENT METHOD IN ABAQUS SOFTWARE

This paper deals with the punctureability of a steel plate by a projectile at different angles of attack. The effect of the projectile angle on the force required to penetrate a plate made of A36 steel is presented using Finite Element Method calculation software. Using Abaqus software, a dynamic model of a projectile striking a plate was modelled and the force required to penetrate a 5 mm thick steel plate was presented. The introduction gives an overview of the genesis of the topic and a brief historical background. The chapter on numerical analysis presents the numerical model used and how the simulation was modelled. In the conclusions, a summary of the results was formulated and conclusions were drawn regarding the observations and insights of the analysis. The force required to penetrate the plate was observed to increase with increasing projectile angle of attack and it was found that, as the angle of the plate increased, the force required to penetrate increased.

Penetration trajectory of rigid projectile in the heterogeneous meso-scale concrete target

For the normal penetration of a symmetrical rigid projectile into a concrete target with coarse aggregates, the lateral deflection may occur under certain conditions depending on geometrical parameters of the projectile, impact velocity and coarse aggregate distribution. In this work, four dimensionless numbers of projectile, that is, impact factor [Formula: see text], length-to-diameter ratio [Formula: see text], nose factor [Formula: see text] and the relative location of mass center [Formula: see text], are employed to study the effects of projectile parameters on the deflection of penetration trajectory. Numerical studies based on three-dimensional (3D) meso-scale concrete model are conducted and the projectile trajectories are obtained under different dimensionless numbers. According to the development of the deflection angle during the rigid projectile penetration into meso-scale concrete, the motion of the projectile can be divided into four stages, that is, initial deflection, rapid change, deflection rebound and final stage. The numerical results show that, for the same meso-scale concrete target, the deflection of the projectile trajectory becomes larger with the increases of [Formula: see text], [Formula: see text] and [Formula: see text], while the deflection angle of projectile decreases with the increase of [Formula: see text].

Basketball self training shooting posture recognition and trajectory estimation using computer vision and Kalman filter

Abstract Self-shooting training is one of the fundamental criteria for success in basketball. Particularly, young players increase their performance with regular training. However, the training process becomes painful and time-consuming without a coach since the incorrect shooting posture causes missing shots, leading to reluctance. In this research, a self-shooting posture algorithm is developed to track the movement of basketball players and give them feedback about their position, angle, and basketball projectile trajectory information. The proposed algorithm uses computer vision techniques and Kalman filter to detect the best projectile trajectory using initial conditions such as acceleration due to gravity the initial velocity at the angle of launch having certain horizontal distance to the rim and the rim distance from the ground The acceleration of both gravity and air drag are altered by predefined parameters, including the drag coefficient basketball mass ball radius and silhouette area The proposed algorithm provides the shooting angle in real-time by placing the projectile angle on to the cropped image of the player posture and draws the projectile trajectory towards the basketball hoop According to the results, the players having a specified height can achieve the best shooting at the angle with air drag force. On the other hand, if there is no air resistance, the best shooting angle is deviated significantly. The other stats that are a total time of travel, maximum horizontal distance, maximum height and the time until the top are also given along with the results.

MD Simulation of the Laser Effects on Stopping for B+ Ion in Plasmas

In this work, the laser effects on the stopping for boron ion in plasmas are studied by molecular dynamics (MD) simulation. The expressions of the stopping power is derived based on the potential. The effects of different laser intensity, laser frequency, laser angle, plasma density and electron temperature on the stopping power of B+ ion are discussed. The results tell that the stopping power of B+ ion will decrease significantly with the increase of laser intensity, and the laser intensity has a strong modulation effect on the stopping power. On the other hand, when the included angle between the laser and the moving direction of boron ion is in the range of 0 to π / 2, the stopping power decreases gradually with the increase of the projectile angle. On the other hand, the influence of plasma parameters on the stopping power of boron ions is also very obvious. When other parameters are given, the increase of plasma temperature or the decrease of plasma density can decrease the value of stopping power.

Ballistic performance of hybrid structure with perforated panel

Motivated by the active demand for the high performance and lightweight structures in the protection fields, this study experimentally and numerically investigated the ballistic performance of a novel ceramic-metal hybrid structure compounded with perforated panel. Though, the perforated panel could lead to the obvious deflection and serious erosion of the projectile, the hybrid structure with perforated panel exhibited only slightly better performance than that with normal panel due to the limitation of perforated panel to the rotation of the whole projectile. The research about the anti-penetration characteristics of hybrid structure with perforated panel indicated that the separation distance, panel structure and striking angle could affect the structure performance. The performance of the target would significantly enhance with increase of the panel thickness, panel hole size and projectile initial obliquity, if the separation distance between the panel and frame was large enough. Finally, the performance of the hybrid structure with optimized perforated panel was explored, and the results exhibited that the optimized structure showed 15% better performance and twice more deflection angle of projectile than the original structure with normal panel.

Research on anti-penetration performance of composite armor of steel/composite materials

The anti-penetration performance of the composite armor structures, which are composed of steel, Kevlar composite, and ultra-high molecular weight polyethylene (UHMWPE) composite, were investigated numerically. The effects of composite armor configurations, the thickness of back plates, the shapes and incident angles of projectile on the anti-penetration performance were analyzed. The results indicate that the configuration with steel, Kevlar and UHMWPE on the first, second and third layers of the composite armor have the better anti-penetration performance. As the thickness of the composites back plate increases, the specific energy absorption of the composite armor decreases while the anti-penetration performance of the composite armor increases. In addition, it can be also found that the ball-headed projectile has stronger penetration ability than the flat-headed projectile of the same weight, and the penetration ability of projectile decreases with the increase in the impact angle of projectile.

Research on Oblique Penetration of Projectiles into Targets of Different Materials

In order to study the trajectory deflection of projectile penetrating obliquely into different materials, the Lagrange algorithm of LS-DYNA was used to simulate the three-dimensional model. The impact angle of projectile is 70°, the concrete target and the soil target are penetrated respectively. The state of the target, the strain nephogram and the stress nephogram of the target under the maximum overload are obtained. The curves of penetration depth, penetration velocity, overload and energy are analyzed. The results show that: in oblique penetration, the projectile’s trajectory deflects more in the process of entering the concrete target, and then deflects less; the trajectory deflection of the projectile is small in the process of entering the soil target and a certain distance after it, but it becomes larger when it is fast out of the target.

A line laser detection screen design and projectile echo power calculation in detection screen area

A line laser with high power as the background light source for the design of a new photoelectric detection target is proposed in this paper, aiming to improve the detection ability of the traditional photoelectric detection target under low background illumination. The laser emitted pulse waveform function and the laser echo pulse response function were used to establish the mathematical model of the reflected echo power of projectile in the detection area and derive the calculation function of minimum detectable echo power in the line laser detection screen, according to information of the line laser emitted power, incident angle of projectile, duration time and detection distance of projectile passing through the line laser detection screen. Calculations and experimental results showed that the design method of line laser detection screen and calculation model of laser echo power are reasonable, and the detection ability of line laser detection screen is obviously higher than that of traditional photoelectric detection screen, especially in low background illumination; at the same time, the designed line laser detection screen was used to combine a six line laser detection screen intersection test system, based on live ammunition for shooting. The test system is stable and able to obtain the dynamic parameters of the flying projectile, verifying that the design of the line laser detection screen in new photoelectric detection target can be suitable for shooting range test applications.

Impact mechanisms of aggregate on rigid projectile normal penetration into concrete target

<p indent=0mm>Concrete failure mechanisms under projectile penetration at a mesoscale level have recently attracted researchers’ attention. Based on the three-dimensional (3D) mesoscale concrete model, the influences of aggregate strength, size, and volume fraction on deflection angle and penetration resistance of projectile were analyzed during the process of rigid projectile penetration into the concrete. Four stages of projectile deflected during the process of depth penetration were described. The measurement of the deflection angle of the projectile during the penetration process revealed the factors affecting ballistic stability. These factors were investigated quantitatively, and their critical values affecting the deflection angle of projectile were obtained. The effects of the key variables of coarse aggregate on penetration resistance were quantitatively studied. Then, the applicable conditions to satisfy the homogeneous assumption and the upper bounds of aggregate size and volume fraction were identified. The latter influenced the penetration resistance and were dependent on the aggregate configurations. Finally, the influencing mechanisms of coarse aggregate on the rigid projectile normal penetration into mesoscale concrete were described. The results reported here provide a theoretical and practical background for design optimization and safety assessment for protective engineering structures.

Models of a hybrid wheeled hopping self-balanced robot

Combining wheeled structure with hopping mechanism, this paper purposes a self-balanced hopping robot with hybrid motion pattern. The main actuator which is the cylindrical cam, optimized by particle swarm optimization (PSO), is equipped with the motor to control the hopping motion. Robotic system dynamics model is established and solved by Lagrangian method. After linearization, control characteristics of the system is obtained by classical control theory based on dynamics equations. By applying Adams and Matlab to simulate the system, hopping locomotion and self-balanced capability are validated respectively, and result shows that jump height can reach 750 mm theoretically. Then PID control scheme is developed and specific models of hardware and software are settled down accordingly. Finally, prototype is implemented and series of hopping experiments are conducted, showing that with different projectile angle, prototype can jump 550 mm in height and 460 mm in length, transcending majority of other existing hopping robots.

Numerical study of influence of target thickness and projectile incidence angle on ballistic resistance of the GFRP composites

In this present work, the ballistic resistance of GFRP composite was investigated against 7.52 mm diameter hemispherical nose shaped projectile. The impact tests have been recreated by doing three-dimensional nonlinear finite element analysis on LS DYNA code. The numerical outcomes such as residual and ballistic limit velocity have been found to have close connection with the test results available in literature. The residual velocity of projectile, ballistic limit velocity and energy retaining limit and failure of the composite have additionally been discussed with changing target thickness and projectile impact angles. From the numerical outcomes, it is clear that the target thicknesses and impact angle of projectile shows critical contribution on the ballistic resistance of the target.

What Projective Angle Makes the Arc-Length of the Trajectory in a Resistive Media Maximum? A Reverse Engineering Approach

We consider the motion of a massive point-like projectile thrown with initial velocity with respect to horizontal in a two-dimensional vertical plane under the influence of gravity in a viscose media. Two different velocity-dependent resistive media models are considered—linear and quadratic. With an objective to utilizing a Computer Algebra System (CAS), specifically Mathematica [1] numerically we solve the corresponding equations of motions. For a set of compatible parameters characterizing viscose forces graphically we display comparing the trajectories explicitly showing the impact of the models. Utilizing the model-dependent trajectory equations numerically we evaluate their associated arc-lengths. What distinguishes our approach vs. the existing body of work is the notion of the “reverse engineering”. Meaning, utilizing our numeric data we establish their corresponding analytic counter parts. Ultimately, utilizing both outputs numerically and analytically we determine the matching initial projectile angles maximizing their respective arc-lengths.

Oblique penetration of ogive-nosed projectile into aluminum alloy targets

To better understand the oblique penetration behavior of ogive-nosed projectile into aluminum alloy targets, penetration experiments with impact velocities ranging from 700m/s to 1100m/s and oblique angles of 0, 10°, 20° and 40° were conducted. The Length to Diameter (L/D) of the projectiles were 3 and 4, respectively. Failure modes of target and penetration trajectory were obtained from penetration experiments. Based on the local interaction theory (LIT) and resistance to penetration in dynamic expansion theory (DET), a model to depict penetration trajectory was developed by taking the effects of free surface and wake separation/reattachment into account. The effects of free surface and wake separation/reattachment on penetration trajectory were analyzed by combining the experimental data and calculated results. The results showed that the calculation results were in good agreement with the corresponding experimental data. Besides, influences of oblique angle, impact velocity, and L/D of projectile on the penetration trajectory were discussed based on the calculation and experimental result. Ranges of increments of attitude angle of projectiles and oblique angle at the impact velocity of 900m/s were 98% to 274% and 10° to 30°, respectively. Similarly, the increments of attitude angle of projectile varied from 205% to 128% as the impact velocity increased from 800m/s to 1000m/s when the oblique angle was 20°. When it come to the influence of L/D of projectile on the penetration trajectory, the increments of attitude angle of projectiles were 178% and 79.5% for the L/D were 3 and 4, respectively. In summary, the penetration trajectory became more stable with the increase of L/D of projectile and decrease of impact velocity and oblique angle.

Analysis of the Projectile Angle Dependence of Pulse Shapes from a Nano-Porous Silicon Charged Particle Detector

Analysis of the Projectile Angle Dependence of Pulse Shapes from a Nano-Porous Silicon Charged Particle Detector

Motion Characteristics After Ricochet: An Experimental Investigation

Abstract The ricochet behaviour of the air–water trans-media vehicle (AWTMV) during water-entry crossing was experimentally investigated. Three types of small-scale AWTMV including cone, ogive, and flat nose were used in the test. The underwater trajectory, velocity, and inclination angle of projectiles during the ricochet process were obtained using a high-speed camera. The angle change of the AWTMV and the ratio of the residual velocity are introduced. Based on this result, the relationship between the ricochet responses and initial conditions was derived. The results of this study show that (1) a small incident angle and great velocity make the occurrence of ricochet behaviour easier, (2) the stability of the trajectory of projectiles with cone, ogive, and flat nose weakened in turn at the same initial conditions, (3) the angle change and the ratio of the residual velocity are linear functions of the incident angle and velocity.

Predicting Soccer Ball Target through Dynamic Simulation

The intelligent sports analysis of a soccer ball requires accurately simulating its motion and finding the best design parameters (position and orientation) to kick the ball. An optimization method is proposed to plan, evaluate, and optimize the traveling trajectory of a soccer ball. The theoretical studies go through the multi-body dynamics modeling, dynamic simulation, and optimal objective modeling Based on Newton second law and Hooke’s law, the motion of a soccer ball is established as the time-dependent ordinary differential equations (ODEs). The expected target is expressed as a function of all design parameters. An example is used to simulate a soccer ball shooting a goal. The result of optimization design has given the most optimal combination of the design parameters, which involve theinitial velocity,initial projectile angle, andinitial orientation angle. This research provides a useful method in predicting the trajectory and adjusting the design parameters for the optimization design of a soccer ball motion.

Explosion force and shape fitting based modelling of dynamic virtual crater deformation

The dynamic deformation of virtual terrain is an important research content to improve the dynamic adaptability of virtual geographic environment, which can support the research of disaster simulation, combat simulation and so on. It is also a novel method to support human-environment interaction research in the community of geographic information science. In this paper, the dynamic generation of bomb crater is taken as an example to study the construction method of virtual terrain deformation model. Starting from the formation process of crater in explosive mechanics, the deformation model is coupled with the calculation method to control the radius and depth of crater shape. Through the method of geometric fitting, the shape of crater is modeled in different regions and the basic crater model is established. On the basis of the basic model, the incidence angle of projectile is introduced to build the relationship model between crater deformation and incidence angle of projectile. Based on the Digital Terrain Model (DTM), the terrain data model is improved by coupling the radius coefficient and depth coefficient related to the geological characteristics, and the crater shape algorithm reflecting the geological characteristics is proposed. Finally, the Perlin noise is added to realize the disturbance of the elevation value of each position point in the crater zone. The simulation environment of crater deformation is established by Unity, and the crater model is simulated and verified. The results show that the crater model can basically reflect the impact of different projectile incidence angle, explosion equivalent and geological characteristics. The deformation state of crater is similar to the actual situation. The research results can provide support for the simulation of the dynamic process of the crater produced by the projectile touch-down explosion in the virtual battlefield environment.