Computer Simulation of Elastomeric Blade and Annular Specimens Testing Taking into Account the Deformation Rate of Their Working Parts

Computer simulation of blade and annular samples made of polymer viscoelastic materials testing has been carried out. Calculations have shown that the rate of material deformation in the working part of the blade specimen can differ significantly from that calculated by the movement of tensile testing machine grips. This is due to the unevenness of the cross-section of blade sample: in the middle (working part) it is constant, and at the ends its area increases. As a result, inhomogeneous stress fields arise in the material, which leads to a variable deformation rate of the specimen working part, even in case when grips move at a constant speed. This effect is not significant at small deformations and a low strain rate and can be ignored in principle. However, in the case of large extensions high speeds, it can seriously distort the test results. According to the authors, the way out of this situation is that, in experiments with viscoelastic polymers, it is better to use annular specimens with the same cross-section along the entire length, rather than blade ones. As shown by computer calculations, in this case, this problem almost completely ceases to exist.