AN ANALYSIS OF AXISYMMETRICAL AXIAL COLLAPSE OF ROUND TUBES

Different size tubes of aluminium and mild steel were subjected to axi al compression in an Instron machine. The tubes chosen were such that they collapsed in axi-symmetric concertina mode. Typical load-compress ion curves and deformed shapes of the collapsed tubes are presented. T hese reveal that the axi-symmetric folds formed in the deforming speci mens extend both inside and outside of the line of original tube radiu s, and the ratio of the inside to outside fold lengths depends on the tube dimensions. Considering the tube collapse mechanism as observed e xperimentally, an analysis is presented in an attempt to predict the m ean collapse load and the postcollapse load-compression curve. The com puted values of the mean collapse load and the load-compression curve during a load oscillation, are presented and compared with the experim ents, as well as with some existing theoretical results.