Energy Absorption of Thin-Walled Circular Tubes with a Sinusoidal Spiral Structure

A thin-walled tube with a predesigned spiral structure, named as the sinusoidal spiral tube (SST), was proposed to improve the energy absorption performance of the traditional circular straight tube and sinusoidal corrugation tube (SCT). A prototype of the SST was fabricated through additive manufacturing and its mechanical properties were tested. The numerical results were consistent with the tests. The effect of geometric features involving amplitude and pitch on energy absorption has been investigated through a series of numerical simulations. The results showed that there are six representative deformation modes and these modes transformed clearly under the action of amplitude and number of turns. On the other hand, the initial peak force was significantly reduced by 53.57-85.34% compared to the straight tube. The stability of plateau force was greatly improved by the spiral structure. The specific energy absorption increased by more than 15% compared to the SCTs under pinned-pinned and fixed-fixed boundary conditions, attributed to the transformation of the deformation mode and the increased number of folded lobes in the straight part. Last but not least, a theoretical model was proposed to predict the mean crushing force of the novel structure under free-free boundary conditions. It showed a good agreement with the numerical results.