Due to extremely different vehicle structural performance it is required to individually analyze vehicle stiffness in any situation where accurate results of calculating crash speed are needed. From the beginnings of vehicle stiffness modelling, by Emori, Campbell or any of their successors, methods of establishing equations are constantly improved. Nowadays, it is well known that normalized crush energy (known as EAF-Energy of Approach Factor) vs deformation can be successfully approximated with linear relationship using results from NHTSA 30 m/h frontal crash test speed. For higher speeds, bi-linear appeared to be accurate enough in most cases. But, thereare certain cases where different relationship could give better results.Some researchers showed that nonlinear relationships could be also successfully used. In this work, all known attempt from previous researchers where exercised on a YUGO GV vehicle. For this vehicle there are three NHTSA full frontal tests available. Using those results, it was concluded that, although bi-linear relationship could be successfully used, best performance was achieved by combined approximation. Linear up to speed of 30 m/h and quadratic above that speed. This approximation gives best results in upper register of speeds, thus it is useful for very deep crash deformations.Using computer for analysis eliminated complicated calculations, so establishing such relationships is facilitated. It is important to notice that this kind of approximation cannot be applied in situation where only one crash test point is known. So, field of application is very limited. The full text of this paper may be found at: http://www-nrd.nhtsa.dot.gov/pdf/esv/esv21/09-0424.pdf For the covering abstract see ITRD E145407.
Samenvatting