scholarly journals The Analysis Of The Vibratory Movement Of The Gun Barrel And Its Influence On The Firing Accuracy

2015 ◽  
Vol 21 (3) ◽  
pp. 883-887 ◽  
Author(s):  
Alin-Constantin Sava ◽  
Ioan-Liviu Piticari ◽  
Diana-Georgeta Nistoran ◽  
Cristian-Emil Moldoveanu
Keyword(s):  
High Speed ◽  
Firing Process ◽  
Torsional Vibrations ◽  
Bending Vibrations ◽  
Modern Equipment ◽  
Gun Barrel ◽  
Flexural Vibrations

Abstract It is known that the forces and shocks that occur during the firing process of a firearm induce vibrations to the barrel of the weapon and to the weapon as a whole. There are flexural, longitudinal, radial and torsional vibrations. The most important ones are considered to be the flexural or bending vibrations, especially the ones recorded in the muzzle section. This paper presents a method of recording the flexural vibrations of the barrel in the muzzle section of a 5,56mm automatic rifle and the influence of muzzle devices, using modern equipment (high speed cameras) and dedicated software.

Heat Transfer Characteristics of Various Gun Barrels Under Different Operating Conditions

2019 ◽  
Author(s):  
Mohamed Gadalla ◽  
Muhammad Jasim ◽  
Omar Ahmad
Keyword(s):  
Heat Transfer ◽  
Thermal Management ◽  
Cross Section ◽  
Wall Temperature ◽  
Circular Cross Section ◽  
Typical Case ◽  
Operating Conditions ◽  
Firing Process ◽  
Transfer Model ◽  
Gun Barrel

Abstract The thermal stability parameter is an important parameter for predicting the lifespan of structures. In this paper, a two-dimensional transient heat transfer model of machine gun barrels undergoing continuous firing developed and analyzed for different geometries and thermal properties. The model for the transient thermal analysis is based on the forced convection heat transfer at the inner surface of the gun barrel. Finite element simulations were performed to predict the interior and exterior barrel temperature profiles and temperature contours after continuous firing process. The incomplete Cholesky Conjugate Gradient (ICCG) solver was adopted in solving unsymmetrical thermal transient analyses. The material thermal behavior studied for the basic circular cross section of gun barrels showed that the lowest inner wall temperature was for high rounds was achieved in steel barrels due to the rapid conducted and convective heat transfer to the environment. While the highest inner wall temperature was recorded for ceramic STK4 barrels and an increase of inner wall temperature by 17% was observed as compared to the typical case of circular cross section steel barrel. In general, a higher inner temperature in the gun barrel is undesirable and harm due to the possibility of reaching the cook-off scenario at earlier rounds. Results concluded that non-circular geometries with constrained cross section areas of typical case improve thermal management and the hexagonal geometry had the best thermal management and could provide more rounds for users. In addition, titanium barrels would have a weight drop of 41% while the overall barrel’s temperature increases by 49%.

Paper 4: Opening, Carding and Spinning Preparation Machines

1966 ◽  
Vol 181 (12) ◽  
pp. 1-7
Author(s):  
H. Catling
Keyword(s):  
High Speed ◽  
Unit Length ◽  
High Amplitude ◽  
Torsional Vibrations ◽  
Stick Slip ◽  
Periodic Disturbance ◽  
The Past ◽  
Machine Utilization ◽  
Lubrication Conditions ◽  
New Machine

There are no serious bearing problems in opening and carding machines. Except for the high-speed beaters and cylinders, occasionally-oiled plain journals were long regarded as adequate despite the fact that many of them operated under boundary lubrication conditions. Stable hydrodynamic film conditions were maintained in beater and cylinder bearings and some simple form of lubricant reservoir was usually provided. In recent years the introduction of shift working and high machine utilization factors have led to a demand for machines requiring a minimum of attention. This demand is being met by the use of prepacked, sealed ball or roller bearings at all points. Perhaps the most serious and intractable bearing problem in the whole field of textile machinery manufacture is encountered in drawframes and speedframes. For uniformity of the drawing action by which the fibres are straightened and finally attenuated to form a roving, it is necessary for all the drafting rollers to rotate perfectly smoothly. Unfortunately the loading conditions and the rotational speeds of some of the rollers are such that there is often a high liability to the occurrence of spontaneous stick–slip torsional vibrations. In other cases there is an incipient liability to stick–slip vibration and quite small gearing faults, of the appropriate frequency, are sufficient to precipitate high amplitude oscillations. At the frequencies commonly observed the non-uniformity of the drawing action introduces into the sliver or roving a periodic disturbance of a wavelength so short that it is not readily apparent in the delivery from the affected machine. Subsequent drafting, however, increases the wavelength and the ultimate yarn exhibits appreciable variations in mass per unit length and in twist distribution. As these variations are strictly periodic they form objectionable interference patterns when used as weft in either woven or knitted cloths. New machine designs and the use of new types of bearings have largely solved these problems and at the same time greatly increased operating speeds. The comber, too, has been intensively developed during the past ten years and a number of lubrication and wear problems have required attention.

Numerical Simulation of Gun Bore Damage during Engraving Process of Driving Band

2017 ◽  
Vol 1142 ◽  
pp. 363-366
Author(s):  
He Yang Sun ◽  
Chang Zhi Jia ◽  
Yao Xin He ◽  
Tian Xiao Cui
Keyword(s):  
Damage Mechanics ◽  
Failure Process ◽  
Damage Model ◽  
Firing Process ◽  
Computation Method ◽  
Damage Behavior ◽  
Damage And Failure ◽  
Gun Barrel ◽  
Safety Design ◽  
Microscopic Damage

A Damage mechanics finite element numerical computation method was established based on HLC microscopic damage model to solve the problem of damage, crack initialization and growth inside bore during the firing process. The damage and failure process of the bore surface was simulated numerically during multiple rounds of firing. The law of the barrel material performance changing with the number of firing rounds was analyzed during the engraving process of the driving band and compared with the experimental results. It is proved that HLC microscopic damage model can show the complicate damage behavior and predict the cracking defect, which provides a reference for safety design of the gun barrel.

scholarly journals The influence of the internal ballistic pressure on the rifled barrel stress response

2020 ◽  
Vol 70 (2) ◽  
pp. 41-46
Author(s):  
Abaci Boukera ◽  
Aleksandar Kari ◽  
Damir Jerković ◽  
Nebojša Hristov
Keyword(s):  
Mathematical Model ◽  
Stress Response ◽  
Cross Section ◽  
3D Models ◽  
The Other ◽  
Firing Process ◽  
Propellant Combustion ◽  
Gun Barrel ◽  
Walled Cylinder ◽  
Good Agreement

This paper focused on the 12.7 mm gun barrel stress response caused by the pressure of the gunpowder gases. During the firing process, the barrel is loaded by different mechanical, chemical and thermal loads. In this paper except the pressure of the propellant combustion, all the other loads were ignored. The pressure loads are obtained with a mathematical model of the interior ballistic. The Lame equations for the thick-walled cylinder were used to calculate the barrel stress response. The loads are applied on a certain barrel cross-section for a defined time. Two 3D models of the barrel with and without grooves were used to perform a numerical simulation. A comparison between results for the two types of barrels shows a good agreement between the stresses obtained by the analytical and numerical methods.

The Applicability of Fuzzy Control for Flexible Mechanisms

1995 ◽  
Author(s):  
David G. Beale ◽  
Shyr Wen Lee
Keyword(s):  
Fuzzy Control ◽  
High Speed ◽  
Fuzzy Controller ◽  
Bending Vibrations ◽  
Bending Vibration ◽  
High Speeds ◽  
Sound Control ◽  
Elastic Transverse ◽  
Flexible Mechanisms ◽  
Crank Mechanism

Abstract The nonlinear nature of high speed, flexible rod mechanisms has been previously confirmed, both experimentally and analytically. Therefore, sound control system design of flexible mechanisms must necessarily be based on nonlinear control. Active control via fuzzy logic is assessed as a means to suppress the elastic transverse bending vibration of a flexible rod of a slider crank mechanism of a slider crank mechanism. Several pairs of piezoelectric elements are used to provide the control action. Sensor output of deflection is fed to the fuzzy controller, which determines the voltage input to the actuator. A three mode approximation is utilized in the simulation study. Computer simulation shows that fuzzy control can be used to suppress bending vibrations at high speeds.

Torsional Vibrations of the Steam Turbine Shaft Line and Estimation of the Residual Life of Its Elements

2020 ◽  
Vol 63 (6) ◽  
pp. 91-98
Author(s):  
Vladimir Grabovskii ◽  
Keyword(s):  
Steam Turbine ◽  
High Speed ◽  
Residual Life ◽  
Operating Time ◽  
Electromagnetic Transients ◽  
Torsional Vibrations ◽  
Steam Turbines ◽  
Shaft Line ◽  
Operating Modes ◽  
Design Life

A comparative quantitative assessment of the damage and residual life of the shaft line elements for differ-ent types of high-power steam turbines at the end of their design life is made by mathematical modeling. The analysis covers all elements of the shaft line: from the steam turbine Central pump to the turbine generator ex-citer. The simulated circuit includes turbo generators, transformers, gate converters, AC and DC power lines. When modeling, an approach is used from the position of proper coordinates, which provides maximum meth-odological consistency of the models of the listed devices and allows you to directly reproduce electromagnetic and mechanical transients with the determination of instantaneous values of currents, voltages, electromagnet-ic and torsional moments. To estimate damage, we used the deformation criterion for soft and hard loads in the zone of low-cycle and force criterion in the zone of multi-cycle fatigue. The influence of the number of starts and running time of a steam turbine on the damage and residual life of its shaft elements is studied. When de-termining the remaining life, in addition to starts, other abnormal operating modes of the turbo generator were taken into account during the turbine operating time: short circuits and their disconnections, unsuccessful high-speed automatic re-activation, subsynchronous resonance due to both the operation of the control system of the PPT and the automatic generator excitation regulator. The influence of attenuation of electromagnetic transients in the generator and damping of torsional vibrations on the degree of reduction of the residual life of the shaft elements is analyzed. The results obtained can be used for a comprehensive solution of the issue of further operation of steam turbines that have spent their design life.

Lateral and Torsional Vibration Analysis of Elastic Robot Manipulators With Prismatic Joint

2002 ◽  
Author(s):  
Mete Kalyoncu ◽  
Fatih M. Botsalı
Keyword(s):  
Robot Manipulator ◽  
Equations Of Motion ◽  
Rotational Inertia ◽  
Torsional Vibrations ◽  
Bending Vibrations ◽  
3 Dimensional ◽  
Prismatic Joint ◽  
Lagrange’S Equation ◽  
Runge Kutta Method ◽  
Euler Bernoulli Beam

Lateral and torsional vibrations of a robot manipulator with an elastic arm sliding in a prismatic joint are analyzed. The elastic arm is assumed as an Euler-Bernoulli beam. The mass of the end-effector is assumed as a point mass attached at the end of the elastic arm. The prismatic joint experiences 3-dimensional translational and rotational motion. The prismatic joint is assumed as rigid and frictionless. Rotational inertia of the beam is taken into consideration in obtaining the equations of motion. Elastic deformations are assumed as linear and small displacements. Axial vibrations are not considered but the effect of axial force is taken into account in the analysis. Elastic arm experiences both bending vibrations in two directions and torsional vibrations. The equations of motion are obtained by Lagrange’s equation of motion. Numerical solution of the equations of motion are obtained by Runge-Kutta method. A computer program is developed for implementation of the presented technique. Numerical simulations are presented in the form of graphics. Presented method is found to be versatile in dynamic analysis of elastic robot arms.

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