| Abstract: | A nonlinear version of the phenomenological theory of long-term strength of polymer materials (viscoelastic bodies) is proposed.
It is based on the introduction of a function accounting for the damage accumulation connected with changes in the load intensity.
The form of this function may be determined from the results of testing the material with a load changing with time in a certain
way, for instance, periodically. As a parameter, the function contains the rate of the changing load or the frequency for
periodic loads. For a quasi-isotropic material, the basic relationships of the theory proposed are generalized to the case
of combined stresses. The durability (failure time) calculations of the material based on this theory are compared with experimental
data for a number of polymer and composite materials in a wide range of loading modes.
Translated from Mekhanika Kompozitnykh Materialov, Vol. 35, No. 5, pp. 585–594, September–October, 1999. |
