Bullet Motion Research Articles

Analisis Kebutuhan Pengembangan Alat Physics Bullet Motion Berbasis Mikrokontroler Untuk Menstimulus Pemahaman Konsep Fisika Siswa SMA Pokok Bahasan Gerak Parabola

This study aims to determine and analyze the need for the development of microcontroller-based physics bullet motion tools to stimulate students' concept understanding on the subject of parabolic motion. This type of research is Research and Development (R&D) using the 4D research method (define, design, develop, disseminate) focused on the define stage. At the define stage, a needs analysis (need assessment) was conducted. This research is a quantitative descriptive research. Data collection techniques in this study were observation and questionnaire to analyze the needs of physics teachers and students of class XI MIA MAN 2 Deli Serdang. Based on the results of the research conducted, it can be concluded that 1) Teachers need learning media in the form of teaching aids that can help stimulate understanding of concepts on the subject of parabolic motion 77.5% with the category agree. 2) Students have an interest in the implementation of learning by conducting experiments and using learning media in the form of teaching aids by 100% with a strongly agreed category. 3) There is no use of learning media in the form of microcontroller-based props that can help stimulate understanding of physics concepts on the subject of parabolic motion by 100% with a strongly agreed category

Human vulnerability assessment based on bullet motion and cavity expansion model with tissue identification

In human vulnerability assessment, the wound characteristics are derived from a single soft media penetration experiment, and there is a lack of mathematical model or algorithm to accurately describe the bullet motion (consider bullet rolling) and temporary cavity variation during bullet penetration into different soft media. This paper derives a bullet motion and cavity expansion-contraction model for bullet penetration into soft tissue; Established a dynamic wound reconstruction model based on neural networks that considers tissue differences. Assessment of damage to tissues using the Abbreviated Injury Scale; Developed software for assessing human vulnerability based on dynamic wound reconstruction. Research results show that the bullet motion model and the cavity expansion-contraction model can predict the characteristic volume of the wound and the temporary cavity profile changes during bullet penetration more accurately; the maximum temporary cavity diameters of the muscle wound, the cardiac wound, and the muscle-cardiac-muscle coupling wound are 183.6, 158.06, and 174.74 mm respectively, and using the cavity in a single target as the basis for human injury assessment will introduce errors. The process of bullet penetration into soft tissue can be accurately described based on a predictive model that considers tissue differences. This paper provides the model that improves the accuracy of human injury assessment compared to existing penetration models.

Effects of Cylindrical Structure on Bullet In-Bore Action Process

To explore the effects of bullet cylindrical difference on in-bore dynamic engraving resistance and muzzle swing, a finite element model of bullet-barrel interaction is built. With the proposed model, real bore bottom pressure curves are obtained through experiments. In the numerical simulation, the in-bore motion processes of two all-copper bullets with different cylindrical structures are reproduced according to the real bore bottom pressure curves, so as to qualitatively analyze the relationship between bore pressure curves and bullet in-bore motion. The association between curve inflection points and bullet motion is identified, and the engraving forces of the two bullets are found to exhibit roughly the same trend. In addition, there is an abnormal phenomenon that the bullet with a shorter engraving length should have a larger engraving force. This is due to the interaction between the shape of bore pressure curves and the engraving process, as well as the larger muzzle swing caused by straight slotted structures that have a shorter engraving length. The findings of this study can provide a basis for the design of internal ballistics and the further analysis of the effects of in-bore motion on external ballistics.

Signal Processing Method of Bullet Motion Acceleration Based on Frequency Division of Pressure Signal

Signal Processing Method of Bullet Motion Acceleration Based on Frequency Division of Pressure Signal

ANALYSIS OF VERTICAL MOVEMENTS ON FREEDOM AND BULLET MOVEMENT EVENTS USING VIDEO TRACKING METHOD

Analysis of vertical motion in free fall and bullet motion with the video tracking method has been carried out. This study aims to analyze the vertical motion pattern in the free fall and bullet motion, specifically the ball launching from the edge of the table. The research was carried out by rolling the ball until it slid and releasing the ball from the edge of the table until it experienced a free fall motion with the height of the table from the two activities of about 1 meter. This activity was carried out repeatedly until obtaining 5 videos of each event and recorded using the Vivo android camera. Furthermore, researchers analyzed using the Tracker application to obtain information data about vertical motion patterns, graphs of changes in position with time, and graphs of velocity against time. Result regressive analysis can derive equations Vy = Ax + B and Y = Ax + B

Experimental and numerical investigation on penetration of clay masonry by small high-speed projectile

This study investigates a kind of masonry consisting of clay-fired brick (fc = 10 MPa; ρ=1.38g/cm3) and mortar (fc = 10 MPa; ρ=1.8g/cm3). Clay-fired brick masonry connotes a traditional construction material of old architecture and public buildings. We carried out penetration experiments in which four clay-fired brick walls employing two different patterns were subjected to impact from small high-speed projectile, i.e. 12.7 mm armor-piercing explosive incendiary projectile and material tests in which the static and dynamic compressive strengths of clay-fired brick and mortar were determined by quasi-static and SHPB (Split Hopkinson Pressure Bar) tests. The experimental data include hit and exit velocities, damage configuration of clay brick masonry and mechanical properties of material at low and high strain rates, though which influence of thickness and bonding patterns of wall on kinetic loss of bullet, the damage patterns of masonry observed experimentally and dynamic increase of material strengths are analyzed. To keep minimum boundary inconsistency with reality, full 3D detailed finite element model consisting of two different material is established. Sharing common nodes and employing automatic tiebreak contact are combined to reduce computational time usage of large-scale model. For description of clay-fired brick and mortar Riedel–Hiermaier–Thoma (RHT) material model is employed. Material parameter set is derived based on experimental data, available literature and engineering assumptions. The numerical simulations study the mesh resolution dependency of material model, reproduce the crucial phenomena of masonry in experiment acceptably and offer more time-resolved insight into motion of bullet in the process of penetration. The feasibility of means of constructing finite element model and applying RHT model to the masonry herein and analogous constructions is explored through numerical investigation.

Method of Conversion for the Ballistic Coefficient of Bullets

A method is examined that permits the ballistic coefficient (BC) of a bullet to be converted based on universal expressions: in the Ciacci law and the air drag law of 1943, i.e., within the framework of laws that extend to the territories of the former USSR countries; to the standards G7 and G1, i.e., within the framework of standards that are the most-used worldwide; in the air drag law of 1943 and to the standard G7, i.e., bringing a BC value to the form that is used on the territories of the former USSR countries (including Ukraine) or to the most-used form worldwide (including NATO member-countries). The relation is formulated on the basis of the central design of an experiment that describes the range of values for an examined process. The above approach enables BC to be brought to an easy-to-use form on the basis of its known value in any law (or to a standard) for analysis of exterior-ballistic characteristics or computations of a bullet velocity at an arbitrary range during field tests of armored targets without bulky equipment for bullet velocity measurements. An examined process is reliably described with the approved mathematical model of bullet motion in air, as the solid body motion, based on the system of four differential equations of the first order. The adequacy of empiric expressions is verified by estimating the standard deviation of values gained with the mathematical model of bullet motion and polynomial as well as by their comparison with the accuracy of determining the ballistic coefficient (no more than 10-3 for the G7 and G1 standards and no more than 10-2 for the Ciacci and 1943 laws).

Aplikasi KALFIS (Kalkulator Fisika) berbasis matlab untuk membantu analisis eksperimen fisika

The purpose of this research is to produce the MATLAB-based physics Calculator application to help analyze physics experiments on the concept of mechanics. With the application of Physics calculator the student will easily analyze the physics experiments quickly and valid. The stage of the implementation consists of the preparation, the research is only in the stage of making the product is a calculator physics application. The results indicated by the KALFIS application can work well proved to be able to analyse and calculate the concepts of mechanics such as GLB, GLBB, and bullet motion.

Cell adhesion during bullet motion in capillaries.

A numerical analysis is presented of cell adhesion in capillaries whose diameter is comparable to or smaller than that of the cell. In contrast to a large number of previous efforts on leukocyte and tumor cell rolling, much is still unknown about cell motion in capillaries. The solid and fluid mechanics of a cell in flow was coupled with a slip bond model of ligand-receptor interactions. When the size of a capillary was reduced, the cell always transitioned to "bullet-like" motion, with a consequent decrease in the velocity of the cell. A state diagram was obtained for various values of capillary diameter and receptor density. We found that bullet motion enables firm adhesion of a cell to the capillary wall even for a weak ligand-receptor binding. We also quantified effects of various parameters, including the dissociation rate constant, the spring constant, and the reactive compliance on the characteristics of cell motion. Our results suggest that even under the interaction between P-selectin glycoprotein ligand-1 (PSGL-1) and P-selectin, which is mainly responsible for leukocyte rolling, a cell is able to show firm adhesion in a small capillary. These findings may help in understanding such phenomena as leukocyte plugging and cancer metastasis.

A new motion model of rifle bullet penetration into ballistic gelatin

An accurate description of the motion of bullets in ballistic gelatin penetration can only be given if a corresponding mathematical model is derived. In this paper, change of the effective wetted area of the bullet is studied well with the increase of angle of yaw in the penetration process. By introducing an area detached ratio and the influence of slenderness, a novel framework is proposed for drag and lift coefficients. Further, a new motion model of rifle bullet is established based on the new frameworks and validated by comparison with the results from experiment data and FEA. The comparative analysis shows that results of the new motion model have a better fit with experiment data than that of the traditional models in previous literatures and the proposed framework for drag and lift coefficients is better than the traditional ones in literatures by comparison with the numerical results. In addition, the calculation of the new motion model is in great accordance with FEA in terms of penetration depth, deflection path, yaw angle, velocity, lift force and drag force at different initial conditions. Benefitting from the motion model based on the new frameworks for drag and lift coefficients, the behavior of rifle bullet in gelatin penetration can be characterized accurately, the prediction of the distribution of energy deposited along the penetration trajectory and the potential for incapacitation of rifle bullets may become possible.

Impact Study of Bend Tube on Bullet Initial Disturbance under the Action of Gravity

In order to study the influence of bend tube on firing accuracy due to gravity, a finite element model of sniper rifle, only considering the interaction between bullet and tube, was established based on nonlinear finite element method. The initial disturbance of bullet was taken as a measuring standard of firing accuracy. The model was used to simulate the launch process of sniper rifle under the condition of gravity static equilibrium in the method of the mixing calculation which had advantages of both dynamic explicit algorithm and static implicit algorithm. The simulation results show that vertical stiffness increases due to gravity and then the instantaneous velocity and attitude of bullet are largely influenced. Bending tube has a great influence on bullet motion.

Axial‐Symmetry Numerical Approaches for Noise Predicting and Attenuating of Rifle Shooting with Suppressors

The moving bullet out of a rifle barrel is propelled by a fired explosive charge. Subsequently, a disturbed muzzle blast wave is initiated which lasts several milliseconds. In this study, axially symmetric, unsteady, Large Eddy Simulation (LES), and Ffowcs Williams and Hawkins (FWH) equations were solved by the implicit‐time formulation. For the spatial discretization, second order upwind scheme was employed. In addition, dynamic mesh model was used to where the ballistic domain changed with time due to the motion of bullet. Results obtained for muzzle flow field and for noise recorded were compared with those obtained from experimental data; these two batches of results were in agreement. Five cases of gunshot including one model of an unsuppressed rifle and four models of suppressors were simulated. Besides, serial images of species distributions and velocity vectors‐pressure contours in suppressors and near muzzle field were displayed. The sound pressure levels (dB) in far field that were post‐processed by the fast Fourier transform (FFT) were compared. The proposed physical model and the numerical simulations used in the present work are expected to be extended to solve other shooting weapon problems with three‐dimensional and complex geometries.

The Magnetohydrodynamics of Supersonic Gas Clouds: MHD Cosmic Bullets and Wind‐swept Clumps

We report an extensive set of two-dimensional MHD simulations exploring the role and evolution of magnetic fields in the dynamics of supersonic plasma clumps. We examine the influence of both ambient field strength and orientation on the problem. Of those two characteristics, field orientation is far more important in the cases we have considered with β0 = pg/pb ≥ 1. That is due to the geometry-sensitivity of field stretching/amplification from large-scale shearing motions around the bullet. When the ambient magnetic field is transverse to the bullet motion, even a very modest field, well below equipartition strength, can be amplified by field line stretching around the bullet within a couple of bullet crushing times so that Maxwell stresses become comparable to the ram pressure associated with the bullet motion. The possibility is discussed that those situations might lead to large, induced electric potentials capable of accelerating charged particles. When the ambient field is aligned to the bullet motion, on the other hand, reconnection-prone topologies develop that shorten the stretched field and release much of the excess energy it contains. In this geometry, the Maxwell stresses on the bullet never approach the ram pressure level. In both cases, however, the presence of a field with even moderate initial strength acts to help the flow realign itself around the bullet into a smoother, more laminar form. That reduces bullet fragmentation tendencies caused by destructive instabilities. Eddies seem less effective at field amplification than flows around the bullet, because fields within eddies tend to be expelled to the eddy perimeters. Similar effects cause the magnetic field within the bullet itself to be reduced below its initial value over time.For oblique fields, we expect that the transverse field cases modeled here are more generally relevant. What counts is whether field lines threading the face of the bullet are swept around it in a fashion that folds them (leading to reconnection) or that keeps them unidirectional one each side of the bullet. In the second instance, behaviors should resemble those of the transverse field cases. We estimate that this quasi-transverse behavior is appropriate whenever the angle, θ, between the motion and the field satisfies tan θ 1/M, where M is the bullet Mach number.From these simulations, we find support in either field geometry for the conclusions reached in previous studies that nonthermal radio emission associated with supersonic clumps is likely to be controlled largely by the generation of strong magnetic fields around the perimeters of the clumps, rather than local particle acceleration and field compression within the bow shock. In addition, since the magnetic pressure on the nose of the bullet likely becomes comparable to the ram pressure and hence the total pressure behind the bow shock, the gas pressure there could be substantially lower than that in a gasdynamical bullet. That means, as well, that the temperature in the region on the nose of the bullet would be lower than that predicted in the gasdynamical case. That detail could alter expectations of the thermal emission, including X-rays and UV-IR lines.

Cosmic bullets as particle accelerators and radio sources

We have simulated in two dimensions the dynamical evolution of dense gas clouds(`cosmic bullets') moving supersonically through a uniform low-density medium. The diffusive shock acceleration of relativistic protons (cosmic rays) and their dynamical feedback on the background flow are included by the two-fluid model for this process. The acceleration of relativistic electrons is approximated by a test-particle model, and a passive magnetic field is followed by a simple advection scheme. Strong bow shocks, with Mach numbers similar to that of a bullet's motion, are the most important particle accelerators in the flow, while tail shocks and shocks inside the bullets do not play generally significant roles in this regard. For our simulation parameters, approximately greater than 10% of the initial bullet kinetic energy is converted to a combination of internal energy of gas and cosmic-ray protons by the time the bullets begin to be disrupted. Characteristically, the cosmic rays gain several percent of the available kinetic energy. Bullet destruction on timescales only a little larger than the ram pressure bullet crushing time begins in response to Kelvin-Helmholtz and especially to Rayleigh-Taylor instabilities along the forward bullet surface. For dense bullets this happens before the bullet is stopped by ram pressure. According to our simple model for synchrotron emission from relativistic electrons accelerated and transported within the flows, that emission increases rapidly as the bullet begins to fragment, when it is strongly dominated by field enhancement in sheared flows. Synchrotron emission from the acceleration region within the bow shock is, by contrast, much weaker.