Experiments on snap buckling, hysteresis and loop formation in twisted rods

John Michael Tutill Thompson, V. G. A. Goss, G. H. M. Van Der Heijden, S. Neukirch

Research output: Contribution to journalArticlepeer-review

57 Citations (Scopus)


We give the results of large deflection experiments involving the bending and twisting of 1 mm diameter nickel-titanium alloy rods, up to 2 m in length. These results are compared to calculations based on the Cosserat theory of rods. We present details of this theory, formulated as a boundary value problem. The mathematical boundary conditions model the experimental setup. The rods are clamped in aligned chucks and the experiments are carried out under rigid loading conditions. An experiment proceeds by either twisting the ends of the rod by a certain amount and then adjusting the slack, or fixing the slack and varying the amount of twist. In this way, commonly encountered phenomena are investigated, such as snap buckling, the formation of loops, and buckling into and out of planar configurations. The effect of gravity is discussed.

Original languageEnglish
Pages (from-to)101-102-111
Number of pages11
JournalExperimental Mechanics
Issue number2
Publication statusPublished - Apr 2005


  • twisted rods
  • rod experiments
  • snap buckling
  • loop formation
  • snarling
  • hockling
  • welded boundary conditions
  • nitinol
  • bifurcation


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