Ultimately straightened spiral springs designed for reinforcing thermally shrinking polymer composites are considered from the viewpoint of their operation properties. The dependence of the degree of contraction of such springs (i.e., of the degree of thermal shrinkage of the composites) primarily on the spring index is determined. It is found that the method of ultimate extension of spiral springs allows one to determine the boundary deformation corresponding to the elasticity limit of the material of a spring wire with a high degree of accuracy.

An expression has been developed that generalizes three basic geometric schemes of film deformation (axial, planar, and biaxial extension) and also all intermediate schemes. The system of quantitative identification of nonuniformly biaxially oriented films according to their transverse extension has been tested on six different film types.

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.

The determination of the swell factor of a polymer jet extruded from a cylindrical or flat die is examined. Relations are obtained for the dependence of the swell factor on shear rate and shear stress, expressed in terms of the constants of the rheological model.

A geometrical method of comparing steady-state flow in uniaxial tension and in simple shear is proposed. This method is based on a comparison of the deformation regimes relative to the principal axes.