Wyniki wyszukiwania - BazTech

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Numerical analyses of the V-shaped deflector effectiveness

Panowicz R., Konarzewski M., Trypolin M.

Journal of KONES

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2016

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Vol. 23, No. 2

269--274

EN

One of the most effective ways to protect mobile objects from the effects of the pressure wave originating from the detonation of a landmine or an explosive charge is to use a special design of the bottom of the protected vehicle. Such structure, called the deflector, in most cases has the shape of the V letter. Article presents the study of effectiveness of the V-shaped deflector. Authors prepared numerical model of a ballistic pendulum consisting of the 1 meter long HEB220 H-beam, suspended using four parallel steel ropes. In the front part of the beam, deflector was mounted. The test component was loaded with pressure wave coming from the detonation of an explosive charge. The article presents an analysis of the ability of the deflector to disperse and/or absorption of energy, depending on the type of the used explosive material and its mass. Studies have been done on the basis of numerical analysis performed with use of the finite element method with explicit integration over time scheme, implemented in the LS-Dyna software. For generation of the pressure wave originating from the detonation of explosive charge ConWep algorithm was used. It uses the predefined by the user geometric and mass parameters, and TNT equivalent to the generation of a pressure pulses.

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Influence of dimensional proportions of cylindrical explosive on resulting blast wave

Panowicz R., Trypolin M., Konarzewski M.

Journal of KONES

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2016

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Vol. 23, No. 4

375--380

EN

Explosives are broadly used today in many applications, both civilian and military. Many experiments involving explosives use either ball or cylinder charges. However, there can be raised a question whether an exact shape influences the resulting blast wave, and, additionally, if the length to diameter ratio of the cylinder influences the wave. To answer the question, numerical analysis was conducted. A 3D model of the charge was constructed in LS-Prepost software and calculated with use of an explicit FEM method in LS-DYNA software. To determine the change of character of the blast wave, the dimensions of the charge change, whereas the mass and distance from the centre of the charge are constant. Several length to diameter ratios was tested, starting from 0.25, to 2, in 0.25 increments. Two explosives, HMX and TNT, were used. As expected, the resulting Blast wave was different in each case, with 100% difference in pressure values between 0.25 and 2 L to D ratios, especially along the length axis of the cylinder. The results show that the exact diameters of the charges need to be taken into consideration while determining a type of charge to be used as well as determining the goal to be achieved during a particular conducted experiment.

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Analysis of the detonation initiation point position influence on the cylindrical fragmentation warhead effectiveness

Panowicz R., Konarzewski M., Trypolin M.

Journal of KONES

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2016

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Vol. 23, No. 1

263--270

EN

The article presents results of the numerical analyses of the fragmentation warhead, which is one of the key elements of the missile used to combat anti-tank missiles. The fragmentation warhead is composed of such elements as outer casing, inner casing, explosive material and fragmentation liner. The fragmentation liner is built from steel spheres or cylinders embedded in epoxy resin. As a result of the explosive material detonation the pressure wave is generated, which affects the liner, causes its fragmentation, and drives each splinter. In order to perform numerical analyses the model of the cylindrical fragmentation warhead with a diameter of 80 millimetres and a length of 100 mm was prepared. The fragmentation liner consists of steel spheres with a diameter of 5 mm. It was assumed in simulation that the detonating material is the plastic explosive C4. The influence of the position of the explosive charge detonation initiation point of the fragmentation warhead on its effectiveness was studied. Effectiveness was evaluated by measuring the maximum speed obtained by the fragments and their spatial distribution. A three-dimensional model of the studied system has been prepared using the MSC Patran software and the numerical analyses were performed using the finite element method with explicit scheme of the time integration implemented in the LS-Dyna solver. To model gas domain Arbitrary Lagrangian-Eulerian (ALE) method was used and interaction between gas and solid body was modelled with FSI coupling.

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Numerical comparison of blast waves generatedby cylindrical explosive charges with varying shapes and materials

Panowicz R., Trypolin M., Konarzewski M.

Computer Assisted Methods in Engineering and Science

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2016

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Vol. 23, no. 4

206--212

EN

A significant influence of explosive charge geometry is frequently observed during experimental testing.In this paper, the effect of explosive charge shape, along with its material properties, on the generatedblast waves is studied. The FEM analysis was conducted for six different explosive materials and threedifferent cylindrical shapes, with geometrical proportions of length L to diameter D varying between 2, 1and 0.25 and constant charge mass. We found that the blast wave generated by detonation is susceptibleto shape changes. However, the different explosive materials were influenced by the charge shape in almostthe same way, with only insignificant differences resulting from the material properties.