Axisymmetric axial crushing of thin frusta

A mathematical model for the axisymmetric axial crushing of thin frusta is presented which considers total outside straight folds and takes into consideration the variation of circumferential strain during the formation of a convolution. A mathematical procedure for the calculation of the variation of crushing load has been developed in the paper. It has been observed in experiments on cylinders as well as frusta that the first limb of the first fold remains straight contrary to other folds where it is curved, thus showing that the flexural energy absorption in the first fold is less. It has been considered in the analysis by introducing a parameter `aʹ which when taken as zero makes it valid for first fold and taking its value as unity makes it valid for other folds. The size of fold and the variation of crushing load are found to be in good agreement with the experimental results.