Effect of Aluminium Foam Density on the Energy Absorption Characteristics of S-rail structure

In the past few decades big emphasis is given on energy absorbing memebers in automotive structures to meet the NCAP (New Car Assessment Programme) requirements in passenger car safety. Many design and material changes are being incorporated to improve the vehicle safety. Structures which are filled with foam have shown better energy absorbing behaviour compared to the bare tube structures. Studies have also shown that the density of foam influences energy absorption behaviour of the sturcutre. In the present work, S-rails structure has been considered to evaluate the energy absorption characterisitcs of S-rail filled with different densities of aluminium foam and wall thickness. Energy absorption behaviour of S-rail without foam and with foam of 92%, 81% and 74% porosity is studed at a speed of 17.77m/s (64 km/h) as per NCAP standard. Foam filled S-rails absorbs 55% more energy compared to baseline model of S-rail. Energy absorbed by wall of S-rail alone when filled with foam is 40% more than wall of baseline model because of interaction effect. S-rail with 81% porosity and wall thickness of 1.5E-3 m (1.5 mm) weighs 30% less than baseline model. It is thus observed that foam filled S-rails structures can be used for vehicle weight reduction with better energy absorption.