Ageing of a polymeric engine mount investigated using digital image correlation

Polymeric engine mounts have been widely used as vibration isolators in vehicles. In general, understanding ageing-dependent stiffness is important for life cycle design. In this paper, a new experimental procedure is developed to study the ageing mechanisms of service-aged engine mounts using digital image correlation measurements. The present contribution demonstrates that the leading factors for ageing-dependent stiffness are, not only the elastic modulus variation, but also the creep deformation and micro-structural change. The results show that pure thermal effects, such as that used to simulate ageing, leads to a uniform change in the rubber component inside the mount. This is not the same as the service-aged mount behaviour. In addition, the cross-sectional creep deformation dominates the increase in rigidity. Finally, the results suggest that micro-structural change may also lead to the stiffness variation of the mounts with high working mileage.