Optimisation of a viscoelastic damping material using dynamic mechanical analysis

Abstract

Reducing vibration in marine craft can return a wide range of benefits from a reduction in noise output, resulting in increased passenger and crew comfort, to increasing component life. Damping is one method of reducing structural vibration, by which mechanical vibrational energy is dissipated into heat through a viscoelastic material. In order for these materials to be effective, their properties must be well understood. Dynamic mechanical analysis (DMA) is one method to determine parameters relating to material behaviour under flexural stress. In this paper it is used to optimise a viscoelastic damping material to fit specific requirements. The product requirements were defined by a specific structural vibration problem with a low temperature operational range of -5 °C to 5 °C (23 °F to 41 °F). Previously, a viscoelastic damping material had been developed for a rail application, with operating temperatures around -20 °C (-4 °F), along with another optimised for standard ambient temperatures. A variety of simple chemical formulations were prepared adjusting the blend ratio of the two different polymers used in these established products. Samples were tested and analysed through the DMA method to determine the optimum damping performance over the required temperature range before the product was applied in a marine application. The optimum blend of the harder and softer polymer at these temperatures was 75:25, resulting in a viscoelastic damping material that is effective at the designated temperature for 16, 25 and 50 Hz. Loss factor peaked at a tan δ of 0.69 at 0 °C for the proposed product compared with 0.55 and 0.66 for the -20 °C (-4 °F) and standard ambient temperature variants respectively. The usefulness of DMA for research and development of products with specific requirements is discussed with reference to this method applied in this project.