The Influence of Foam Density on Specific Energy Absorption of Rectangular Steel Tubes

Abstract

Problem statement: In general, the automotive structure is targeted to absorb high impact energy with least mass as much as possible. This is in order to limit the fuel consumption. 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 study is also aimed to investigate more detail of the behavior of foam-filled structure under impact. Approach: The study was carried out experimentally by using steel tubes of 2 dimensions i.e., 1×2 and 2×2 inch 2 . The thickness of each tube was varied from 1.2, 1.5 and 1.8 mm. Each tube was filled with polyurethane foam. The density of foam was varied from 100, 200 and 300 kg m −3 . The foam-filled tubes were crushed axially using a 1,000 kN universal testing machine. The crush speed was 50 mm min −1 . The load -displacement were recorded and the energy absorption of each specimen was calculated and compared. In this study the specific energy absorption was used as a key indicator, rather than energy absorption, in order to take the mass increment into account. Results: The experimental observation revealed that the structures failed in square mode with number of fold increases as the density of foam increased. It also found that the foam filled tube with density of 300 kg m −3 absorb energy more than that of the tube with foam of 200 and 100 kg m −3 density and empty tube respectively. However, when taking mass into account, the tube with 200 kg m −3 foam-filled may be the most efficient since it provided maximum specific energy absorption value. Conclusion: The result indicated that the density of foam increases the number of folds in collapsed tubes. The result also revealed that tube with higher density foam can absorb more energy absorption. In addition, it was found that the density of 200 kg m −3 is the optimum value to fill in tube since it offers maximum specific energy absorption.

Application of Cellular Material in Crashworthiness Applications: An Overview

“…Furthermore, increasing the foam density may affect the weight effectiveness of the filled structure. The results obtained by Onsalung et al [58], who investigated the energy absorption behaviour of a square steel tube filled with polyurethane foam, indicated that a filled tube with a foam density of 200 kg.m -3 offers higher SEA than a tube with a density of 300 kg.m -3 .…”

“…The energy absorption of foam filled tubes is mainly related to the density of the foam, where structures with higher foam density have higher energy absorption [44], [58]. Mirfendereski et al [44] reported that the foam density has an insignificant effect on the initial peak load of tapered tube but it has an important effect on other energy absorption parameters such as the absorbed energy, the mean load, and the crush force efficiency which increase as the foam density increases.…”

On the crashworthiness performance of thin-walled energy absorbers: Recent advances and future developments

“…The author suggested that using foam density of lower than 0.6-0.7 g/cm 3 may prevent global bending characteristics in foam-filled circular tubes. The results obtained by Onsalung et al [197], who investigated the energy absorption behaviour of a square steel tube filled with polyurethane foam, indicated that a filled tube with a foam density of 200 kg/m 3 offers higher specific energy absorption than a tube with a density of 300 kg/m 3 . Thornton [200] and Thornton et al [201] found that that weight effectiveness tends to be reduced in a polyurethane foam-filled when the foam density was higher than 220 kg/m 3 .…”

“…The density of a filler material in foam-filled components is the most influencing factor that controls the crush and energy absorbing behaviour of FFTWEA. Generally, A FFTWEA with higher foam density exhibits higher energy absorption capacity [189], [197]. However, increasing the foam density over an optimal value may lead to many serious consequences such as global bending deformation mode, low weight effectiveness, and premature tensile rupture [198], [181],…”

Design of Thin Wall Structures for Energy Absorption Applications: Design for Crash Injuries Mitigation Using Magnesium Alloy

“…It was found that the use of foam-filled tubes will increase the unreformed tube mass. By using foam-filled specific energy absorption will increase and it also increase by increasing the foam density [28].…”