Phase Angle δ

The phase angle δ is a relative measure of the viscous and elastic properties of a material.
It ranges from 0° for a fully elastic material to 90° for a fully viscous material. It can be considered the “degree of fluidity”.

Sinusoidally oscillating shear strain over time (t). The black and red solid lines represent the applied shear deformation and the material response (stress) with a phase angle (δ), respectively. The black arrow illustrates the period (T).

Related Methods