Geometric nonlinearity of mechanical behavior as a consequence of large deformations of springs

Spiral springs used in many fields of technology are usually considered linear mechanical objects, i.e., the dependence of their elongation is in proportion to the applied load. However, under large deformations, this dependence becomes nonlinear, whereas the deformations of a material from which a spring is manufactured remain small and the linearity of the properties of the material is preserved. The theory of large deformations of spiral springs that makes it possible to predict the effective elastic modulus as a function of the elongation ratio has been developed.