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In performing calculations to evaluate passive safety of car seats by computer modelling methods it is desirable to use the final element models (FEM) thereby providing the greatest accuracy of calculation results. Besides, it is expedient to use FEM, which can be calculated by computer for a small period of time to give preliminary results for short terms.The paper describes the features to evaluate a passive safety, which is ensured by the developed KEM of seats with passive head restraints according to requirements of the EURO NCAP.Besides, accuracy of calculated results that is provided by the developed KEM was evaluated. Accuracy evaluation was accomplished in relation to the results obtained the by specialists of the organization conducting similar researches (LSTC).This work was performed within the framework of a technique, which allows us to develop effectively the car seat designs both with passive, and active head restraints, meeting requirements for passive safety.By results of made calculations and experiments it was found that when evaluating by the EURO NCAP technique the "rough" KEM (the 1st and 2nd levels) can be considered as rational ones (in terms of labour costs for its creation and problem solving as well as by result errors) and it is expedient to use them for preliminary and multivariate calculations. Detailed models (the 3rd level) provide the greatest accuracy (the greatest accuracy is reached with the evaluated impact of 16km/h speed under the loading conditions "moderate impact". A relative error of full head acceleration is of 12%).In evaluation by EURO NCAP using NIC criterion a conclusion can be drawn that the seat models of the 2nd level (467 936 KE) and the 3rd level (1 255 358 KE) meet the passive safety requirements according to EURO NCAP requirements under "light", "moderate", and "heavy" impacts.In evaluation by EURO NCAP for preliminary and multivariate calculations a model of the middle level (consisting of 467 936 KE) can be used. The relative error (loading according to figure 6, "moderate" impact) of the full head acceleration makes 22%. By the values of labour costs for its creation and task solution and by errors of results such models can be considered to be rational.The materials presented in paper are used to teach students at the Department of Wheel Vehicles of the Scientific and Educational Complex "Special Mechanical Engineering" at Bauman Moscow State Technical University. |
