Determination of Poisson's ratio of silicone sealants from ultrasonic and tensile measurements

Poisson's ratio is a fundamental material constant arising from the equations of linear elasticity and is a primary input property for finite-element analyses. Elastomers are generally regarded as nearly incompressible materials with Poisson's ratios slightly below 0.5. However, incorporation of particulate fillers may reduce Poisson's ratio significantly. Determining the Poisson's ratio of silicone sealants is an essential task, since these materials are increasingly used as structural adhesives in construction applications, which frequently require finite-element design calculations. The paper reports on the results of a feasibility study aimed at determining Poisson's ratio of three filled RTV silicone sealants based on simple ultrasonic and tensile measurements. Using this method, longitudinal ultrasound velocities of 984-1003 m/s were determined; and from Young's moduli and specific densities, transversal ultrasound velocities of 64-90 m/s and Poisson's ratios between 0.496 and 0.498 were calculated for the three sealants.