Crush characteristic of foam-filled steel tubes

Abstract

Square and circular tubes are generally used as a main frame for vehicle structures, since they are considered as high efficiency energy absorption elements. Therefore, various techniques to increase the energy absorption with less mass increment have been studied for years. One of those techniques is by filling foam in the tube. This paper is aimed to investigate the behavior of foam-filled square and circular tubes under axial load. The study was carried out experimentally by using a number of square and circular steel tubes having various geometries. Each tube was filled with polyurethane foam. The density of foam was varied from 100, 200 and 300 kg/m³. The foam-filled tubes were crushed axially using a 1,000 kN universal testing machine. The crush speed was 50 mm/min. The load-displacement were recorded and the energy absorption of each specimen was calculated and compared. In this paper the specific energy absorption is used as a key indicator, rather than energy absorption, in order to take the mass increment into account. The result revealed that the energy absorption of tube is increased as the density of foam increases. However, the specific energy absorption is not increased in many cases. In addition the collapse modes of the specimens were also discussed.