Dynamic characterization of elastomers using impact testing

Dynamic characterization of elastomers, i.e. laboratory testing and fitting of constitutive models, is quite complicated. The demands on the laboratory equipment and the skill of the personal handling the test equipment are high. Stationary harmonic testing is an established method for evaluating dynamic properties of elastomers. However, it is demanding experimentally when it comes to high frequencies. The purpose of this investigation is to evaluate theoretically if impact testing can be an alternative to the harmonic test method. The impact behavior of an elastomer showing both rate and amplitude dependence is evaluated numerically. It is shown that the stress-strain behavior during impact show similarities to the stationary harmonic behavior of the material. Quantities comparable to the dynamic stiffness and phase angle can be derived from the impact behavior. It is also shown that amplitudes of 1-15% strain and frequency/rate dependence in the range 30-200 Hz, can be resolved with velocity and mass of the impacting body having realistic values. Moreover, a schematic experimental setup is also discussed. Impact testing has a potential to be a very simple method to obtain dynamic data for elastomers, to use in calibration of constitutive models. Alternatively it can be used as a simple quality control of dynamic properties in various elastomeric materials.