Between 1977 and 1980, mainly in the United States and in Australia, independent research centres began to process several statistical data on accidents between vehicles and pedestrians, taking cam, 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 this twenty years period (1977-97) and in documents of EEVC, the scientists describe a proposed test for upper-leg impact; it is represented by the impact of a standardised impactor (that simulate the human leg/pelvis) 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. For that test there's not a "lighter" version provided by ACEA Protocol, so it will works not before 2010 but EuroNCAP rating on pedestrian safety is still working and takes into account the Upper-Leg test too. 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 those 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. The impactor was created in order to evaluate the in several parts of the Upper-leg using two parameters: - Sum of Forces coming from two transducers positioned in the upper and lower part of the impactor, in order to evaluate the injury on the upper (neck) and lower parts of femur bone; - Maximum. bending moment applied on the central part of the element that simulates the femur bone. Those two parameters are useful to evaluate what happens when a pedestrian, that cross a road orthogonally to the vehicle way, is rammed by a car, and hits the Bonnet leading edge with the Upper part of the Leg injuring femur and pelvis zone. Impactor used to evaluate the damage in pedestrian test is made by TRL and is quite similar to the structure of the Human femur: it has a very complicated system to simulate the whole bone-flesh-skin apparatus and, in particular, has two layers of special ConforTM Foam CF-45 Blue that has the same mechanical behaviour of human flesh, in an other scientific paper we have published the results on the dynamic characterization of that Foam at medium and high impact velocity; in this paper we have simulated the whole Upper-leg Impactor, in PamCrash environment, using the ESI formulation of the Skin and using the results of characterization of all other elements with experimental tests. After this 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 Numenc/Experimental correlation is very good and we've numerically certified our impactor. We've also made several tests, whose Experimental results are published, at higher speed and we have obtained some correlation problems because of the critical behaviour of the flesh at high speed simulation but the results on different cases show the same output behaviour, giving us an instrument to resolve that problem.

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

NADDEO, ALESSANDRO;CAPPETTI, Nicola;ANNARUMMA, MARINA;
2004

Abstract

Between 1977 and 1980, mainly in the United States and in Australia, independent research centres began to process several statistical data on accidents between vehicles and pedestrians, taking cam, 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 this twenty years period (1977-97) and in documents of EEVC, the scientists describe a proposed test for upper-leg impact; it is represented by the impact of a standardised impactor (that simulate the human leg/pelvis) 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. For that test there's not a "lighter" version provided by ACEA Protocol, so it will works not before 2010 but EuroNCAP rating on pedestrian safety is still working and takes into account the Upper-Leg test too. 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 those 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. The impactor was created in order to evaluate the in several parts of the Upper-leg using two parameters: - Sum of Forces coming from two transducers positioned in the upper and lower part of the impactor, in order to evaluate the injury on the upper (neck) and lower parts of femur bone; - Maximum. bending moment applied on the central part of the element that simulates the femur bone. Those two parameters are useful to evaluate what happens when a pedestrian, that cross a road orthogonally to the vehicle way, is rammed by a car, and hits the Bonnet leading edge with the Upper part of the Leg injuring femur and pelvis zone. Impactor used to evaluate the damage in pedestrian test is made by TRL and is quite similar to the structure of the Human femur: it has a very complicated system to simulate the whole bone-flesh-skin apparatus and, in particular, has two layers of special ConforTM Foam CF-45 Blue that has the same mechanical behaviour of human flesh, in an other scientific paper we have published the results on the dynamic characterization of that Foam at medium and high impact velocity; in this paper we have simulated the whole Upper-leg Impactor, in PamCrash environment, using the ESI formulation of the Skin and using the results of characterization of all other elements with experimental tests. After this 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 Numenc/Experimental correlation is very good and we've numerically certified our impactor. We've also made several tests, whose Experimental results are published, at higher speed and we have obtained some correlation problems because of the critical behaviour of the flesh at high speed simulation but the results on different cases show the same output behaviour, giving us an instrument to resolve that problem.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11386/1059312
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