Abstract
The bucking problem of compressed coiled springs has been investigated by Haringx and that of twisted coiled springs by Hubbard. In this paper, the buckling condition of coiled springs is derived by considering coiled springs as elastic rods of equivalent rigidities. It is noticeable that the shearing-deformation of coiled springs is large enough to be taken into account in the analysis. Therefore, an equilibrium equation is set up by considering both the bending and shearing deformation of the rod element. The results confirm the theories of Haringx and Hubbard. The experimental results on coiled springs under combined axial deflection and torsion show good agreement with those predicted by the theory.
