Figure 6.

Complex frequency response of the linear rheometer system over a frequency range of 1–400 Hz: (a) magnitude response ∣H(ω)∣ (dimensionless), and (b) phase response δ(ω) in radians. In (a), the damped resonant frequency of the system is observed to be around 142 Hz, where ∣H(ω)∣ is maximum (dotted line). In (b), at the undamped resonant frequency (199 Hz), the phase is at around −π∕2 (dotted line).