Properties of NBR and CR Hyperelastic Materials in a Wide Range of Both Positive and Negative Temperatures

Hyperelastic materials are widely used in many industries. Their use requires thorough knowledge of their strength parameters over a wide temperature range. However, determination of the parameters of hyperelastic materials is still a challenge. Therefore, the paper presents research methodology allowing determination of the properties of hyperelastic materials in a wide range of stretch and temperatures (from +50 degrees C to -25 degrees C) on the example of NBR (nitrile butadiene rubber) and CR (chloroprene rubber) elastomers. On the basis of physical premises, a hyperelastic constitutive model was also modified through introducing an explicit dependence of strain energy on temperature, allowing an accurate reflection of the properties of the tested materials. The material parameters of the adopted strain energy functions for the NBR and CR were determined with R2 not less than 0.999.