Figure 10.

A simple two degree-of-freedom mechanical model exhibiting a notch and phase shift is pictured here. (A) System schematic composed of two connected masses (m), springs (k), and dampers (c). The attachment stiffness of this system ($k_1$) is roughly analogous to the limbal TM attachment stiffness in the full six-degree-of-freedom OCC model from Fig. 3. (B) Frequency responses of the system shown in (B) for parameters: $m_1=1$, $m_2=2$, $k_1=4$, $k_2=3$, $c_1=0.1$, $c_2=0.1$ (the parameter values are chosen for demonstration). The difference, $x_1-x_2$ loosely represents the rotation of the HB in the full OCC system. At the spring/mass resonance frequency of mass $m_1$ when uncoupled from $m_2$ (when $\omega =\sqrt{k_1/m_1}=2$) a phase shift and a local minimum (notch) in $x_1-x_2$ occurs.