Influences of folded walls of square and rectangular sections on their energy absorption capacities

This article investigates lateral flattening process on simple and folded square and rectangular specimens with thin-walled cross-section during the quasi-static lateral compression tests between two rigid platens. Effects of creating the regular folds in lateral walls of square and rectangular samples are studied on their energy absorption behaviors. Furthermore, effects of loading angle on the simple and folded specimens, presence of polyurethane foam on folded rectangular columns and also, specimen length are examined. Firstly, some simple square and rectangular columns are prepared and axially compressed between two rigid platens to create regular folds in the walls of the specimens or to change a simple quadrangular column into a folded specimen. Then, as new tests, the folded specimens are positioned between two rigid platens and laterally compressed in the quasistatic condition that called flattening process. Also, some simple quadrangular columns are used in the lateral compression tests to compare their energy absorption capacities with the corresponding values of the folded specimens during the flattening process. Results show that in the flattening process, specific absorbed energy of square and rectangular specimens with folded walls is considerably higher than the corresponding simple columns. In other words, energy absorption capability by the folded specimens is up to 4.7 times of the simple column with the same mass and it shows interesting advantage of regular folds creation in the square and rectangular columns. Also, in the flattening process, when lengths of a folded specimen and the corresponding simple specimen are the same, total absorbed energy by the folded specimen is 17.9 times of the simple one. Flattening experiments show that when lateral load angle varies, energy absorption capacity by the folded columns changes. Also, it is found that by filling the folded rectangular specimens with the polyurethane foam, its specific absorbed energy increases.