Abstract
Keywords - Rear underrun protection device, ECE R58 regulation, practical testing, computational simulation, non-linear FEM analysis
Abstract - The article presents the principle of non-linear numerical calculation of the rear underrun protection device, which can be used in the motor vehicle approval procedure. The adequacy of the underrun protection device is examined according to the regulation ECE R58, in which all the geometrical and mounting requirements, as well as the procedures for adequacy checking of the protection device, are precisely stated. The regulation permits the computational simulation of the protection device. The safety inspection procedure of the protection device is not required if it can be proved by a calculation procedure that the protection device meets the demands, stated in the regulation ECE R58 (1).
The stated possibility was the basis for doing research in the calculation inspection of protection devices with the aid of the computational simulation, which enables a faster and, above all, cheaper estimation of the adequacy of the protection device in comparison with the practical test. This article describes the requirements and procedures for the realization of a proper computational simulation that is based on the finite element method (FEM). For the realization of this article, we have analysed a frequently used protection device design that was composed of a cross-member and two vertical pillars made of steel. The cross-member was joined to the two vertical pillars by a weld seam. The practical test was performed in accordance with the regulation ECE R58. We aimed at the best possible simulation of the conditions, which were present in the practical testing, in computational analysis, as well. The calculation was carried out with LS-Dyna 970 non-linear solver. We have taken into consideration the material non-linearity, contacts, geometrical non-linearity, and the quasi-static way of loading.
A very good accord of the practical test results of the protection device with the computational analysis leads us to a conclusion that the safety inspection procedure of the protection device can be replaced by the calculation analysis.