Figure 5: Torsional response and negative effective moment of inertia.
From: Polarization bandgaps and fluid-like elasticity in fully solid elastic metamaterials
The response function is defined as the ratio of the amplitudes of tangential accelerations at two ends of the sample, with rotational actuation situated at the top the sample (Fig. 3c). The measured (orange markers) and simulated response functions (orange solid curves) are plotted in a as functions of frequency (left axis). A bandgap is seen near 1.3–1.6 kHz. The calculated effective moment of inertia Ix is shown in orange dashed curves (right axis). It is seen that Ix turns negative inside the bandgap. Inset shows a drawing of the sample-kx. (b) Shows the simulated displacement profile of the sample-kx at the lower gap edge (1.3 kHz), inside the bandgap (1.5 kHz), and at the higher gap edge (1.7 kHz). Here actuation position is on the top of the meta-rod. Black cones indicate the amplitude and direction of the displacement (in logarithmic scales). Colour fields represent the displacement component that is perpendicular to the slicing plane, with red/blue colours representing positive/negative displacement, respectively.
