Mechanical Spectroscopy – Fundamentals

the coupling model Abstract. Mechanical spectroscopy is described as a member of the family of spectroscopic techniques. It is shown that mechanical spectroscopy investigates the mechanical energy absorbed by a physical object subjected to an external time-dependent perturbation field, that is, an impulsed, quasi-static, or harmonic mechanical field over the entire range of attainable frequencies (from 10-6 Hz to 1012 Hz). The modulus of compliance and modulus of elasticity is discussed in terms of generalized susceptibility within the framework of linear response theory. The relationship of the response and relaxation functions to generalized susceptibility is given via the Fourier-Laplace transformation of the relaxation or response function. This approach describes linear mechanical responses to time-dependent mechanical perturbation and enables calculation of mechanical loss in solids. Debye and non-Debye relaxations are briefly described and illustrated. A record of discussions which took place during the Second International School on Mechanical Spectroscopy MS-2 and author’s answers to questions raised after the lecture are included.