Analysis of Axial Crushing of Metallic Round Tubes

摘要

The large deformation behavior of thin walled structures under axial loading, both static and dynamic, has beenstudied extensively for its application to the design for crash energy absorbing devices. In particular round tubes are the mostfrequently used devices that absorb energy by material deformation and have therefore received considerable attention ofresearchers.Models for axial crushing of cylindrical tubes have been developed for both total inside as well as total outsidefolding. These early models do not satisfy the experimental observations where it has been observed that the folds formed arepartly inside and partly outside. In the present paper a simplified straight fold model with partly inside and partly outsidefolding has been developed and the proportion of inside and outside fold lengths have been determined by minimizing theaverage crushing load. The size of fold and mean as well as variation of crushing load has been computed. The difference inthe value of yield stress of material in compression and tension has been incorporated in the analysis. The variation ofcircumferential strain during the formation of a fold has been taken into account. The total inside and total outside foldmodels can also be easily derived from the present model. The results have been compared with experiments and reasonablygood agreement has been observed. The results are of help in understanding the phenomenon of actual fold formation.