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Influence of armoured vehicle's bottom shape on the pressure impulse

Barnat W., Panowicz R., Niezgoda T.

Journal of KONES

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2011

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Vol. 18, No. 1

39-46

EN

This paper presents the results of a numerical analysis of military vehicles hulls mine resistance. The research concerns armours loaded with blast wave from large IED charges in three cases. First is an explosion in Euler domain without any boundary conditions. Second consists of Euler domain with flat bottom and the ground. Third is simulated Euler domain with ground and deflector. Boundary conditions used both in second and third case resulted in growth of the pressure impulse due to the reflection from a rigid obstacle. In the article different hull bottom shapes are compared. The gap between the bottom and the ground is fixed in all cases. Explosion in Euler domain without limitations is added as a reference. The blast wave caused by the detonation (simulated as a point detonation) propagated in cubic mesh with appropriate boundary conditions. Theoretical solution of spherical non-linearity is given in a form of Taylor equations. It was used to verify the numerical model. The research showed that the ground proximity affects the results of the simulation. The pressure impulse is amplified due to the wave reflection from both the bottom of the vehicle and the ground. As well as that, the study confirmed that the usage of the deflector considerably reduces the impact load to the structure.

2

Modelling and numerical simulation of the protectiye shield - protected plate - test stand system under blast shock wave

Klasztorny M., Dziewulski P., Niezgoda T., Morka A.

Journal of KONES

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2010

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Vol. 17, No. 3

197-204

EN

The study presents FE modelling and simulation of a system for range testing of protective shields for light armoured vehicles. The protective shield designed by Authors is used against HE mines and IEDs up to 10 kg TNT. The system consists of the multiple-use portable rangę stand, a protected Armox 500T steel plate and a protective shield. The shield has a multi-layer structure and has the following main layers: PA11 aluminum, SCACS hybrid laminate, ALPORAS aluminum foam, SCACS hybrid laminate, connected together using SOUDASEAL chemo-set glue. The HE spherical charge is suspended centrally at 400 mm distance from the top surface of the stand. Overall dimensions of the test stand are approximately 800x800x180 mm, the protected piąte has dimensions 650x650x5 mm, and the protective shield is of 450x450x76 mm dimensions. The system is supported by an additional steel plate stiffening the subsoil. FE modelling, numerical simulations and processing the results were performed for the system under blast shock wave using the following CAE systems: CATIA, HyperMesh, LS-Dyna, and LS-PrePost. The 8-nodes brick finite elements were used, taking into account friction and contact phenomena. Isotropic and orthotropic material models and advanced nonlinear equations-of-state for some parts of the system were chosen, with relevant failure and erosion criteria, including the Johnson — Cook model for Armox 500T steel and PA11 aluminum and the MAT 161 model for plies of hybrid laminates. The shock wave was modelled approximately using the LOAD BLAST ENHANCED option available in LS-Dyna Version 971 R4 Beta code. Numerical simulations were performed for 2 kg TNT.

3

Computer modelling of complex action system of blast wave arising from mine or IED explosion on light armoured vehicle

Panowicz R., Niezgoda T., Barnat W., Sybilski K.

Journal of KONES

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2010

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Vol. 17, No. 4

385-390

EN

In this paper the results of computer simulation of blast wave action arising from mine or IED explosion on wheeled light armoured vehicle will be presented. In the last years the NATO STANG 4569 international standard has been prepared. It describes the test standards concerning the ballistic resistance of vehicles not only to missiles but also to fragments and pressure wave arising from mine or IED explosion. In accordance with this standard the explosive charge is placed under ground surface (independently to the charge position in relation to the vehicle-under the wheel or under the vehicle centre). This case is of frequent occurrence during the different stabilization missions conducted by our troops both in Iraq and in Afghanistan. In the calculations the possibility of coupling between the medium described with the aid of Eulerian equations and the medium described with the aid of Lagrange equations has been used. The coupling enables the complex description of the issue. The detonation process has been described approximately of detonation optics and the behaviour of detonation of explosive device has been described with the aid of JWL equation in common use. Such approach to the subject is sufficient to resolve mast engineer problems. The vehicle has been described with the aid of Lagrange elements with corresponding material properties. The effect of high masses has been taken into account, in particular the effect of engine on behaviour of the object. The adequate coupling of the mediums above- mentioned has been very difficult during the numerical work, but additional taking the ground in consideration has improved considerably the quality of the results obtained which are nearer of the real results.