Lightweight impact crash attenuators for a small Formula SAE race car

Abstract

An important feature of the Formula SAE (Society of Automotive Engineers) race car design competition is that the car must withstand a certain level of frontal impact without intrusion into the driver foot-well area or damaging levels of deceleration to the driver himself. For the car to be competitive, any impact-absorbing structure must be lightweight and hence many teams use aluminium honeycomb inside the car's frontal nose cone. This paper considers an alternative approach based on an array of thin-walled circular tubes attached to the front bulkhead of the car. Experiments have been conducted at the University of Leeds to study the behaviour of empty and honeycomb-filled tubes subjected to quasi-static and dynamic loading. Aluminium (6063 T6 alloy) tubes filled with Nomex® HRH-10 honeycomb were employed in the current study. The experimental programme included five quasi-static tests and four dynamic tests. It was found that the honeycomb-filled tubes absorbed around 10% more energy than the empty tubes. However, the specific energy absorption (SEA) was found to be 15% less than for the empty tubes for the same axial deformation in all the test cases. Numerical simulations have been carried out using the explicit finite element code RADIOSS. Confidence in the present modelling procedure was established through comparison of the numerical results with test data. An excellent correlation of peak loads and energy absorption has been obtained for both empty and honeycomb-filled tubes. Thus, the modelling procedure outlined here can be used with confidence to design the proposed impact attenuator structure and to demonstrate that it meets the crashworthiness requirements of the competition.