A Study on the Influence of the Car Front Side Structural Elements in the Impact Legform Bumper Test

摘要

Statistic studies made in the in the last 30 years have showed that the pedestrians are a category with a high risk in road accidents, especially in the urban areas. For these reasons, governaments have brought in a series of rules whose finality is the reduction of the aggressiveness of cars against pedestrians. These rules define three kinds of impact: head impact (child and adult impact), upperleg impact and lower leg impact. The main problems related to the respect of these rules are linked with a scarse knowledge of impact development and the consequent difficulty of definition of the project criteria. The virtual prototipation thecnics allow a deep knoweldge of the mechanical phenomenon and a preliminarily valuation of the behaviour of a structure subjected to stress and of the cars in the case of pedestrian impact. The goal of this job is the application of the virtual prototiping techniques to understand the influence of the car front side structural elements in the impact legform to bumper test. This impact, provides the measure of 3 magnitudes (knee bending angle, knee shear displacement, tibia acceleration), that must be kept down of the fixed value. Many tests occurred in which a model of the legform impactor made by us, has been thrown on different front side car models with 11.1 m/s of velocity, as the normative specifies. These tests have showed how it is possible to distinguish two tune phases of the legform, and how it is important to abtaine a high energy absorbition from involved element in the first time of impact, to reduce the highest values of measured parameters.