Analysis and Design of Thermally Actuated Micro-Cantilevers for High Frequency Vibrations Using Finite Element Method

Abstract

Vibrational behavior of thermally actuated cantilever micro-beams and their mechanical response at moderately high frequency under a non-harmonic periodic loading is studied in this paper. Two different configurations are considered: 1) a straight beam with two actuation layers on top and bottom which utilizes the bimorph effect to induce bending; 2) a uniform beam with base excitation, where the beam is mounted on an actuator which moves it periodically at its base perpendicular to its axis. Generally, vibrating micro-cantilevers are required to oscillate at a specified frequency. In order to increase the efficiency of the system, and achieve deflections with low power consumption, geometrical features of the beams can be quantified so that the required vibrating frequency matches the natural frequencies of the beam. A parametric modal analysis is conducted on two configurations of micro-cantilever and the first natural frequency of the cantilevers as a function of geometrical parameters is extracted. To evaluate vibrational behavior and thermomechanical efficiency of micro-cantilevers as a function of their geometrical parameters and input power, a case study with a specified vibrating frequency is considered. Due to significant complexities in the loading conditions and thermo-mechanical behavior, this task can only be tackled via numerical methods. Selecting the geometrical parameters in order to induce resonance at the nominal frequency, non-linear time-history (transient) thermo-mechanical finite element analysis (using ANSYS) is run on each configuration to study its response to the periodic heating input. Approaches to improve the effectiveness of actuators in each configuration based on their implementation are investigated.

An Electro-Thermal Actuation Method for Resonance Vibration of a Miniaturized Optical-Fiber Scanner for Future Scanning Fiber Endoscope Design

“…Cantilever design follows the finite element analysis done to investigate the dynamic behavior of a micro-cantilever that is transversely excited at its base using a free-standing metallic actuator that is expanding and contracting due to thermal cycles, reported in our previous works [20][21][22][23][24]. Figure 1 shows a three-dimensional (3D) model of the thermal actuator, dual-clad optical fiber, and fiber cantilever, mounted in the bore of a hypodermic needle.…”

Resonance vibration of an optical fiber micro-cantilever using electro-thermal actuation

“…Indeed, there is non-homogeneity in the temperature distribution along the length [18], the temperature changes in the actuator can be adjusted rapidly according to the magnitude of electrical current and steady-state can be achieved rapidly (for a more detailed discussions check [21]); and (2) Active cooling cannot be practically implemented in this system. However, assuming that, after achieving steady-state, there is a base temperature and Δ ( ) = Δ + Δ , where (Δ ≥ Δ ), the above formula can be valid for the harmonic part.…”

“…This acts as a base excitation for the beam. Komeili and Menon [21,22] studied the response of micro-cantilever beam to thermal cycles at its base, along with sensitivity analysis on the system, using Finite Element method. Later on, they showed an analytical model for a 2 dimensional micro-cantilever excited at its base [23].…”