Axial crushing analysis of tubes deforming in the multi-lobe mode

Similar to the concertina mode, the wall of axially crushed tubes deforming in multi-lobe or diamond mode, will be laid down partly to the inside and partly to the outside of the tube generator with the latter part being smaller than the former. Such proportion of the folding length is known as the eccentricity factor, in both the concertina and multi-lobe modes. The present work examines the collapse of tubes in the multi-lobe in an attempt to evaluate the crushing load using this unique factor. The analysis produced a distinctive value for the eccentricity factor that simplifies the expression for the mean collapse load, which is a function of tube geometry and number of lobes. The analytical outcome for the mean crushing load, the total deflection is in a reasonable agreement with those obtained from experiment. Furthermore, the measured values of the eccentricity factor and the critical folding angles obtained for tubes of different materials and geometric ratios are also in good agreement with those produced by the analysis which postulates that the distinctive value of m is independent of the tube's material and geometric ratios. (C) 1999 Elsevier Science Ltd. All rights reserved.