The aim of the study is to identify the relevant aspects of numerical analysis of impact of projectiles with soft cores into a package composed of thin flexible plies located on the plastic backing. In order to illustrate the problem, normal impact of 7.62 mm TT projectile into an unclamped package comprising 36 plies of Dyneema SB71 supported on the plastic backing was selected. The problem was solved with the use of the finite element method (FEM) with the explicit integration scheme (central difference method) of motion equations in the matrix form. Based on the conducted numerical computations, it was revealed that obtaining the extreme deformations of a projectile soft core and the backing material in Lagrangian description requires employment of adaptive methods. The proposed R-adaptive method performs its role but must be used carefully due to the mass loss which may appear during calculations.
From all the detonation parameters of explosives, “strength” – the capability to perform work is the most important for the user. The detonation of explosives in the blast hole is a quick and complicated process: first there is a detonation pressure causing the crushing of the rock in the vicinity of the explosive, then the pressure of the detonation products causes the cracking of the rock. The article presents the methods of determining the capability to perform work by explosives for civil use (dynamite and ANFO) used in the accredited Laboratory of Explosives and Electric Detonators Testing of the Experimental Mine “Barbara” of the Central Mining Institute – the lead block (Trauzl) method and the ballistic pendulum method. The aim of the research was to determine the relationship between the values of the capability to perform the work received in a ballistic pendulum method and a lead block method. As a result of the performed tests and the analysis of the results, the α-Pb coefficient was determined, which can be used to convert the value of the capability to perform work on the ballistic pendulum to the corresponding value of the capability to perform work in the lead block. At present, the Central Mining Institute is the only Notified Body of the European Union in the scope of Directive 2014/28 /EU, which has a station for smelting lead blocks and equipment and for determining the capability to perform work by explosives in lead blocks – this method was abandoned in other research units for testing with a ballistic pendulum and/or underwater test.
The paper presents the results of experimental-numerical tests of firing at aluminum composite materials. The test materials were manufactured by pressure infiltration of porous ceramic preforms made of -Al2O3 particles in the amount of 30% and 40% by volume. The EN AW-7075 alloy was chosen as the material matrix, and the steel 7.62×39 mm (M 43) FMJ (Full Metal Jacket) intermediate ammunition was selected for firing. In the result of the experiment, the samples were perforated with a clear difference in the muzzle diameter. The projectile with fragments caused damage to up to three reference plates placed behind the samples (witness plates) in composites with 40% of particles by volume. The mechanics of crack propagation during ballistic impacts of the projectile was characterized based on microstructure studies. Then, using numerical analysis of impact load, the examination of composite materials puncture in the ABAQUS environment was carried out. The Finite Element Method (FEM) was employed for the discretization of geometric models using Hex elements. The Johnson-Cook constitutive model describing the relationship between stress and strain in metal-ceramic composites was applied for the analyses. Numerical models were then subjected to numerical verification using smoothed particle hydrodynamics (SPH). Based on the obtained results, it was found that the hybrid FEM/SPH method correlates significantly with the experimental results.
The main objective of this article is to obtain equations of motion of the spin–stabilized projectile in the presence of non–constant wind. Introducing models allowing utilization of inhomogeneous wind is dictated by new possibilities created by the use of e.g. lidars in the Fire Control Systems (FCS). Constant feed of wind data can replace meteorological messages, increasing the FCS effectiveness. Article contains results of projectile flight simulations which indicate the positive effect that the derived explicit form of the model has when considering software development for modern Fire Control Systems.
We describe a new method to separate ballistic from the scattered photons for optical tissue characterization. It is based on the hypothesis that the scattered photons acquire a phase delay. The photons passing through the sample without scattering or absorption preserve their coherence so they may participate in interference. We implement a Mach−Zehnder experimental setup where the ballistic photons pass through the sample with the delay caused uniquely by the sample indices of refraction. We incorporate a movable mirror on the piezoelectric actuator in the sample arm to detect the amplitude of the modulation term. We present the theory that predicts the path−integrated (or total) concentration of the scattering and absorption centres. The proposed technique may characterize samples with transmission attenuation of ballistic photons by a factor of 10-14.
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