Determination of the Dynamic Complex Moduli of Linear Viscoelastic Materials Utilizing Laser Interferometry. Theoretical Considerations

摘要

Two nonresonant techniques for determining the complex Young's modulus and complex shear modulus of linear viscoelastic materials are presented and analytically evaluated. The two methods are developed around the use of the laser interferometer because of its potential in extending the operational range of existing methods. The technique to measure the complex Young's modulus is based on the longitudinal vibration of a fixed-free homogeneous prismatic rod of viscoelastic material subjected to a compressional sinusoidal stress wave. The technique to measure the complex shear modulus is based on the torsional vibration of a fixed-free homogeneous circular rod of viscoelastic material subjected to a torsional sinusoidal stress wave. A brief parameter study is presented to examine the potential of both techniques along with an error analysis. (Author)