Stresses in a Helical Spring of Arbitrary Cross Section With Consideration of End Effects

Abstract

This paper presents expressions for stresses in the spring due to compression or tension in the direction of the axis of the cylindrical coil. In deriving stresses in the spring, it is necessary to first obtain resultant forces and resultant moments which occur in the coil spring. Then the analysis first derives exact results based on three-dimensional curved beam theory in which all displacements and all forces in three orthogonal directions of the coil spring are included with consideration of the constraints of the ends of the spring. Since the boundary shape of the spring is irregular, it is also difficult to satisfy stress-free boundary conditions along the surface of the coil, so that this paper applies the Fourier expansion collocation method and obtains stresses in the coil spring based on the theory of elasticity.