Elastic–plastic theory for initial buckling load of thin-walled grooved tubes under axial compression

The initial buckling load of a tube corresponds to the peak load in the first buckling cycle. In practice, this load is very important for crashworthiness design that gives an indication of the force required to initiate collapse and hence begin the energy absorption process. In this paper, the effects of grooves on the initial buckling load of thin-walled tubes under axial compression are investigated. The grooves are introduced in the tube to force the plastic deformation to occur at predetermined intervals along the tube. The aims are improve the uniformity of the load–displacement behaviour of axially crushed tubes, predict and control the collapse load of the tube. An analytical study based on elastic–plastic deformation is performed on the axial crushing of the thin-walled grooved tubes with alternately inside and outside annular grooves pattern on tube’s surface. The initial buckling load is predicted theoretically and compared with experimental findings. There is a good agreement between them. The results show that grooves can stabilise the deformation and the proposed method could be a good candidate as a controllable energy absorption element.