Optimal sample shape for internal friction measurements using a dual cantilevered beam

Abstract

An optimal shape for internal friction measurements using a dual cantilevered beam is described. The new shape is analyzed by a finite element method, in order (a) to optimize its parameters to reduce parasitic interactions with the sample holder, and (b) to calculate the stress distribution in the vibrating sample. The numerical analysis shows that the interactions between the sample and its holder are much weaker for the new shape than for the classical flexural vibration of a simple cantilevered beam. The predictions of the numerical analysis are compared to experimental results on a niobium sample at low temperature.

Design strategies for controlling damping in micromechanical and nanomechanical resonators

“…Models for adhesion and friction can provide useful qualitative insights into the underlying mechanisms but improving thin-film adhesion and reducing microsliding remains an art. Nevertheless, several general strategies can be formulated: (i) minimize deformations and strains at the interface between the supporting frame and package: for example, by employing the anti-symmetric modes of dual-cantilever beams [60] or double-paddle oscillators [62,63], and acoustically isolating the resonator from the supporting frame and package; (ii) use precisionmachined clamps and avoid spring-loaded clips, gels, polymer-based adhesives, and die bonds for packaging; and (iii) ensure good adhesion between the resonator and supporting frame by activating the substrate before depositing structural thin films, employing adhesion promoters in the form of ultrathin films of Ti or Cr, and using ion-beam assisted deposition techniques [88].…”

Local mechanical spectroscopy with nanometer-scale lateral resolution

“…4͒ developed by Baur. 26,27 The used sample consists of a thin polymer film deposited onto a tuning-fork shaped metal substrate. The metal tuning-fork shaped plate is clamped at one end and excited electrostatically to its second vibrational mode ͑the two arms of the fork vibrate in phase opposition͒.…”

Low-Temperature Mechanical Loss Spectroscopy of 5N Lead

“…The vibrations of the sample were electrostatically excited by an electrode in a vacuum of 10-6 mbar and detection was realized using the same electrode. In order to reduce parasitic interactions with the sample holder, a particular sample shape is used [4]. This technique leads to a deformation measurement amplitude between 10-7 and 10-5.…”