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This research involves the experimental study of lateral flattening of tubular structures. Main goals are investigations of the effects of geometrical discontinuities on energy absorption characteristics of these structures and finding new ways for increasing the energy absorption capacities. Three groups of specimens were investigated: square and rectangular aluminum columns, circular brazen tubes and circular composite tubes where some notches of different lengths were created on various positions of them. The specimens were compressed between two rigid plates during a quasi-static process and their energy absorption parameters were calculated using the testing machine’s data. Experimental results show that numbers of notches on walls of the structures may increase or decrease their energy absorption capability, depending on the notches positions. Square columns with notches on up and down sides are cases in which the amounts of energy absorption are more than their corresponding intact specimens. In most of the specimens, notches lengths had reverse relation with their energy absorption. Behaviors of composite tubes under lateral compression loading are more sensitive to the notches lengths than the other specimens. By changing the notches positions on walls of the specimens, the deformation mode and consequently the energy absorption capability can be determined which is the case that is studied in this research.

This paper investigates the effect of polyurethane foam-filler on the lateral plastic deformation in the circular tubes under radial quasi-static loading, experimentally. For this purpose, the specimens were prepared with five different diameters and thicknesses. For each constant diameter of specimens, several tubes with different lengths were prepared. All geometrical groups of specimens in the lateral compression tests (flattening) were used in empty and polyurethane foam-filled conditions. The effect of length, diameter and wall thickness of tubes on the lateral load, energy absorption and the specific absorbed energy were studied. The experimental results show that the polyurethane foam-filler increase the energy absorption capability of tubes and furthermore the increment of the energy absorption in thinner tubes is more than thicker specimens. Results show that using the polyurethane foam in the circular tubes under the lateral compression works as an excellent filler.