Effects of Cantilever Aspect Ratio and Liquid-Solid Suspensions on Resonance in a Confined Cavity

The dynamic response of millimeter-scale cantilevers was investigated in liquid-solid suspensions. The gap height d between the cantilever and a solid surface was varied from millimeter range to micrometer range. Different Bimorph cantilevers (aspect ratio b/h = 2.0–12.1, where b is the cantilever width and h is the cantilever thickness) were examined. The added mass coefficient increased linearly with aspect ratio. The normalized viscous damping coefficient increased with increasing kinetic Reynolds number but appeared independent of the cantilever aspect ratio. Cantilevers oscillating in liquid-solid suspensions experienced higher effective viscosity than that predicted by shear flow type models. The damping caused by a suspension containing 2% glass beads by volume was significantly stronger than that in a pure liquid for dimensionless particle diameters D_p/d ≥ 0.02.