Many techniques have been developed and verified for measuring the complex Young's modulus of viscoelastic materials. Among them, it is advantageous to use the impedence method for detailed frequency analysis. By this method, a known displacement is applied to a given specimen and the resulting force is measured. The amplitude ratio of the two signals and the phase angle between them are then used to compute the material properties. Althought the cross section of the viscoelastic material could be of any shape, it has been common to use specimen having retangular or circular sections.
In this paper, a way to determin the specimen geometry which is most appropriate for the identification of the complex modulus by impedence method are presented and discussed. The impedence method is analyzed theoretically and experimentally with the various shapes of specimen. Finally, experimental results supporting the theoretical predictions are presented.
