Poisson's ratio and the deflection of a viscoelastic plate

A new method for the measurement of the Poisson's Ratio function of the more rigid plastics is described. The deflection of a freely‐supported circular plate under uniformly distributed load is combined with modulus data obtained in an independent experiment. The apparatus is described, the validity of the relevant elastic stress‐strain formulae are discussed and the results obtained on PMMA and PVC are compared with other published values. It is concluded that this method is at least as accurate as the alternatives, all of which have particular deficiencies, and that it is possibly superior in some respects.