Mechanical spectroscopy

Mechanical spectroscopy measures a material’s response to oscillatory stress or strain, often over varying frequencies or temperatures. Its response reveals elastic behavior, energy dissipation, and processes such as molecular relaxation and phase transitions.

Connect

Dynamic mechanical analysis: A technique that applies oscillatory force to a specimen and measures its mechanical response, often while temperature changes. It is a common experimental method for obtaining mechanical spectra.
Viscoelasticity: The combined elastic and viscous behavior of materials whose deformation depends on time. Mechanical spectroscopy characterizes this mixed response under periodic loading.
Mechanical loss peak: A maximum in measured mechanical dissipation as a function of frequency or temperature. Peak position and shape help identify relaxation processes in a specimen.
Dielectric spectroscopy: The measurement of a material’s electrical polarization response under an alternating electric field. It probes molecular relaxation through electrical rather than mechanical response.
Storage modulus: The in-phase component of a material’s complex modulus, representing energy stored elastically during oscillation. It tracks how elastic stiffness varies with frequency and temperature.
Complex modulus: A complex-valued ratio of oscillatory stress to strain, encoding elastic and dissipative response. It is the central quantity separated into storage and loss components.
Glass transition: A temperature-dependent transition in which an amorphous material changes between glassy and rubber-like behavior. Mechanical response changes sharply as polymer segmental motion becomes accessible.
Impedance spectroscopy: A method that measures electrical impedance as a function of frequency to characterize material processes. Its frequency-dependent electrical signal contrasts with mechanical stress–strain spectra.
Loss modulus: The out-of-phase component of a material’s complex modulus, representing energy dissipated during oscillation. Its peaks expose dissipative processes in a mechanical spectrum.
Linear viscoelasticity: The regime in which stress is proportional to strain and material response does not depend on oscillation amplitude. Small-amplitude spectra are interpreted using this proportional-response assumption.