Lower Leg impactor modelling for Pedestrian Test simulation using F.E.M. explicit codes

In late 70', mainly in the United States and in Australia, independent research centres had processed several statistical data on accidents between vehicles and pedestrians, taking care, obviously, to pedestrians' injury. That problem in the early 80' became also interesting for European research centres. In 1990 a research group of EEVC (European Enhanced Vehicle-Safety Committee) had examined statistical data of past twenty years and scientific research published about this topic, and had presented several documents about "pedestrian test" procedures. In reference papers of period of twenty years (1977-97) and in documents of EEVC, the scientists describe a proposed test for lower-leg impact; it is represented by the impact of a standardised impactor (that simulate the human leg) on car front-part; those documents have been updated in 1994, 1998 and finally in 2002 while Euro-NCAP, since 1998 had used them to realize, in specialized laboratories, tests for giving a rate for car-safety judgement. EEVC wants to introduce those tests for the new homologation program since 2010. A "lighter" version of those tests will be performed on new-cars, also for homologation, using ACEA Protocol, which is easier to per form, since 2005. The most Important Automotive industries had understood the impact of those new regulations about homologation and began to study the problem and particularly how to introduce these new Homologation parameters in their Product development cycles, today based on Virtual Prototyping of the Whole Vehicle and final Physical testing of few physical prototypes. EEVC lower-leg impactor was thought in order to evaluate the injury in several parts of the leg using three parameters: - Deceleration of the higher part of the tibia in order to evaluate the injury on Tibia bone; - Shear displacement in the knee joint in order to evaluate the damage that occurs at the human knee for the displacement of the patella towards the higher part of the Tibia - Maximum bending angle in non-natural way of deformation of the knee (in left or right side) that causes the injury for knee ligaments. Those three parameters are useful to evaluate what happens when a pedestrian, that cross a road orthogonally to the vehicle direction, is rammed by a car, and hits the Bonnet and the bumper by Leg (femur/tibia). Impactor used to evaluate the damage in pedestrian test is made by TRL and is quite similar to the structure of the Human leg: it has a very complicated joint system. In this study we have simulated the Legform Impactor, using FEM processor PamCrash (TM), using the ESI (TM) Kinematic joint formulation. After that work of modelling we have tested the Impactor by the simulation of the Certification Tests, as described in the EEVC and EuroNCAP norms, in order to obtain the same results of the experimental test. The Numeric/Experimental correlation is very good and we've numerically certified our FEM impactor.