The deformation of polymer materials. A review

Abstract

The total deformation in a small neighborhood (in the vicinity) of points can be separated into the following components: elastic, plastic, viscoelastic, and viscoplastic deformations. The mathematical apparatus required to determine each of these deformations has been developed, and each of them may possess physically nonlinear and linear components. The results of tests of certain materials at room temperature are presented in Table 2. If we take the total deformation as 100%, it is apparent from the table that the specific weight of each component of the total deformation varies considerably due to the type of material, and the direction, rate, and duration of the loading. This means that in each individual case, we should establish what deformation components can be disregarded and which of them are determining components. Note that in modern engineering, the appearance of viscoelastic, plastic, and viscoplastic deformations is inevitable, and even desirable. Of all the forms of deformations, elastic deformations are undoubtedly the simplest. There are, however, a number of difficulties in determining the elastic characteristics of a material. Gershberg et al. [2], therefore, investigated certain characteristics of the pulse method of determining the technical elastic constants of fiberglass. They computed the normal modulus of elasticity from the resonant frequency of the first tone of bending oscillations of rod specimens and a ring. They determined the temperature dependence of the shear and normal-elastic moduli on woven-fiberglass specimens cut out along the base, along the weft, and at 45 ° . A quantitative description of the temperature dependence of the dynamic elastic modulus in shear and the loss factor of a rigid cellutar polymer material on the basis of the linear theory of viscoelasticity is given