Dynamic Testing and Constitutive Modelling of NBR Rubbers

The present work describes the compression behaviour of NBR rubber. Experimental tests have been conducted both in dynamic conditions. The latter ones, performed by a polymeric Split Hopkinson Bar, range from 100 to 500 1/s of strain rate. The long lasting pressure wave generated by the adopted SHB permitted to obtain a relatively high strain level in all the tests, up to 0.7-1.0 logarithmic strain. The experimental stress-strain curves were used to fit hyperelastic-perfect viscoelastic constitutive models; in particular, the Ogden and Mooney-Rivlin models were used for the hyperelasticity, while the Prony series was used for the viscoelastic part. The analyses permitted to evaluate the dependency of the storage and loss moduli of NBR as functions of frequency and strain amplitude.