A new model on the buckling of a rod in tubing

An improved helix model is presented for the buckling of a rod in tubing, which includes both the helix section and non-helix sections. The new model simulates the buckling of a rod in tubing more accurately than the helix model since non-helix sections satisfy boundary conditions. Indoor tests are carried out to verify and improve the new model. A comparison of the shortening of the rod based on the helix model and the new model and measured values during tests shows that the new model greatly reduces the error.