Damping of dynamic effects with elastomers in instrumented impact testing

Abstract

The efficiency of four silicon elastomers as damping materials was studied in high rate (2.9 m/s) instrumented impact testing. The measurements were done on injection molded PP specimens. Dynamic effects could be efficiently reduced by all four silicon rubbers. Mechanical damping leads to smooth force versus deflection correlations, which considerably facilitates the determination of valid fracture mechanics characteristics. Damping does not influence the maximum force measured during fracture, KIc is independent of rubber type and thickness. Since the damper consumes considerable energy, GIc is significantly modified by damping, the effect depends both on the viscoelastic properties and the thickness of the damper. The approach proposed earlier for the correction of energy could be applied in all cases where a load versus deflection trace void of oscillations was registered. Similarly to KIc, corrected GIc values proved to be completely independent of the conditions of damping, i.e. the type and thickness of the damper. The parameters of the non-linear constitutive equation which was used to describe the deformation behavior of the damper could not be related to properties determined by simple measurements (hardness, modulus, rebound elasticity, etc.).