The non-linear viscoelastic properties of flat belt and conveyor materials

Three flat belts and one conveyor material were subjected to tensile tests at two different strain rates and oscillatory tests at one strain rate. All the test data correlated well with a 5 parameter Pao-Marln non-linear viscoelastic model. The results obtained were used for extrapolating: (a) stress relaxation at constant strain; (b) Strain relaxation at constant stress; (c) high speed oscillatory tests. Relaxations of stress or strain showed an exponential type decay to a finite limit. In three cases out of four, under fast cycling, the hysteresis loops narrowed to virtual linearity. In one Instance, a cotton belt, the high strain rate data were linear but the hysteresis loop did not narrow to the same extent as the other three materials. The finding of linearity under strain rates normally encountered in industrial drives supplies some evidence, apparently missing hitherto, why one can assume that the material is linear over the active arc.