Open Access

ABSTRACT

Weight And Reliability Optimization Of A Helicopter Composite Armor Using Dynamic Programming

V.C. Santos¹, P.S. Lopes¹, R. Gärtner², A.B. Jorge¹

1 Institute of Mechanical Engineering, UNIFEI - Federal University of Itajubá, Av BPS, 1303, Itajubá, MG, Brazil - CEP 37500-903
2 Institute of Solid Body Mechanics, TUD – Technische Universität Dresden, Fakultät Maschinenwesen, Mommsenstr. 13, 01062 Dresden, Germany

The International Conference on Computational & Experimental Engineering and Sciences 2007, 4(2), 53-58. https://doi.org/10.3970/icces.2007.004.053

Abstract

This work presents an approach for weight and reliability optimization of aeronautical armors. Military and police helicopters are usually exposed to highly risky situations, with a high probability for these aircrafts to be hit by projectiles. In this context, floor aircraft armor can be used to protect the crews' lives. However, the armoring of an aircraft causes an increase in weight. If this extra weight is poorly arranged, the changes in aircraft centroid position may even destabilize the aircraft. Thus, it is essential to design an armor not only to protect the aircraft, but also not to conflict with aircraft design restrictions, such as the maximum allowed weight and the aircraft centroid position. To reach these design objectives, it is necessary to use analytical and numerical tools. In this work, the weight and reliability optimization is made for a helicopter composite armor by means of dynamic programming. An ANSYS/LS-DYNA® model is used for the numerical simulation, using the built-in code for non-linear transient dynamic events, such as the ballistic impacts in study. To simplify the aircraft armor analysis, the protected area is divided into a mesh, consisting of a set of rectangular plates, and only the impact in one plate is considered. In this work, the armor is a thin two-layer plate, wherein the first layer reached by the projectile is made of a ceramic material and the second one is made of a composite material. The impact is assumed to occur in the center of the plate. For each failure mode assumed for the armor, a failure criterion was established. For example, a possible breach is analyzed considering the kinetic energy absorbed by the armor, the permissible displacement for the armor is evaluated considering the displacement of a certain representative point, and limits in weight exist due to limitations in the aircraft centroid path. Optimum values for the weight or the reliability are obtained, complying with the imposed restrictions.

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