On the axial deformation characteristic of PVC foam-filled circular aluminium tube: Effect of radially-graded foam filling

It is known that the foam-filled tubes offer significant improvement in energy absorbing owing to the interaction between the foam filler and the tube wall during axial folding deformation. In this study, an experimental investigation was carried out to clarify the interaction. For this purpose, two main specimen configurations, namely uniform density foam-filled (UDF) and radially-graded density foam-filled (RGDF), were prepared by filling aluminium tubes with PVC foam (60 and 100 kg/m(3)) and tested under axial compression. The experiments revealed that application of radially-graded foam filling to the tube enhanced energy absorption capacity (EAC). EAC of the RGDF and UDF specimens were 48% and 40% higher respectively than that of the base tube. Moreover, the specific energy absorption (SEA) value for the RGDF filled tube was found as 23.8 J/g while it was 21.5 J/g for the UDF filled specimen. From the experimental results, two main influence effectively increased the absorbed energy such as the axial resistance of the foam filler and the squeezed foam between inward parts of tube folds. It was concluded that if a proper foam filling design is applied the contribution of the foam squeezed between inward tube folds would have a noticeable effect on the EAC with higher SEA