The nonlocal multi-directional vibration behaviors of buckled viscoelastic nanoribbons

This paper presents the multi-directional vibration behaviors of buckled viscoelastic nanoribbons based on the nonlocal theory containing scale effect, where the Lagrange’s motion equation is introduced to construct the nonlocal viscoelastic governing equation. The first-order transverse vibration mode and the first-order longitudinal vibration mode are considered to study the influences of the scale characteristics on the natural frequency of two different vibration modes. The Kelvin–Voigt model is used to characterize the material viscoelastic property, and an analytical method is presented to solve the nonlocal viscoelastic vibration behaviors of the buckled nanoribbon containing scale effect. Results show that the scale effect could decrease the natural frequency of buckled nanoribbon with viscoelastic behavior, as well as the half bandwidth during forced vibration. The presented results may be taken as a useful reference for the fabrications and applications of buckled nanostructures-based sensors & actuators, electronics, energy harvesters, etc.

A type of dual-rotor hybrid ultrasonic motor based on vibration of four side panels

Based on vibration of four side panels, a type of dual-rotor hybrid ultrasonic motor without using the torsional piezoelectric ceramics polarized along the circumferential direction is presented. The first longitudinal and the first bending vibration modes of the four side panels are used to indirectly excite the first longitudinal and the second torsional vibration modes of the stator cylinder. There are rectangle piezoelectric ceramics bonded on both sides of the four side panels, which are uniformly distributed along the circumference of the stator cylinder. One pair of panels on the opposite side is used to indirectly excite the first longitudinal vibration mode of the stator cylinder, and the other pair is used to indirectly excite the second torsional vibration mode. The simulation results, using finite element method software Workbench, reveal the operating principles, and the optimal structure is proposed. The appearance size of the prototype is 27.2 mm × 27.2 mm × 70 mm, while the outer diameter of the stator cylinder is 20 mm. The working frequency of the prototype measured in experiment is 44.7 KHz, which is consistent with the numerical results. According to the major mechanical measurement at 450 Vp−p operating voltage and 3.46 N preload, the stalling torque of the prototype is 8 mN·m and the no-load speed is 140 r/min. The experimental results indicate that the motor can operate in the first longitudinal and the second torsional coupled vibration modes transformed from the first longitudinal and the first bending vibration modes of four side panels.