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Mechanical Engineering

2019

Series

Mechanical Engineering Faculty Scholarship

Nonlinear dynamics

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A Parametric Resonator With Low Threshold Excitation For Vibration Energy Harvesting, Shahrzad Towfighian, Wei Yang Apr 2019

A Parametric Resonator With Low Threshold Excitation For Vibration Energy Harvesting, Shahrzad Towfighian, Wei Yang

Mechanical Engineering Faculty Scholarship

A parametric resonator for vibration energy harvesting is presented. Despite large responses from parametric resonance, two major drawbacks of parametric resonance harvesters are the high threshold excitation and narrow bandwidth. We addressed these two shortcomings by adding magnetic nonlinearity to the system. The proposed vibration energy harvester consists of two piezoelectric cantilevers beams, each with a magnetic tip. By controlling the distance between the two magnets, the threshold excitation level needed to trigger the parametric resonance decreases. Combining the softening and hardening behavior of the two magnetically coupled beams increases the frequency bandwidth. In addition, the amplitude of the response …


Dynamic Response Of A Tunable Mems Accelerometer Based On Repulsive Force, Meysam Daeichin, Mehmet Ozdogan, Shahrzad Towfighian, Ronald Miles Feb 2019

Dynamic Response Of A Tunable Mems Accelerometer Based On Repulsive Force, Meysam Daeichin, Mehmet Ozdogan, Shahrzad Towfighian, Ronald Miles

Mechanical Engineering Faculty Scholarship

This paper describes a tunable MEMS electrostatic accelerometer that uses repulsive electrode configuration so that the design is not hampered by capacitive pull-in instability. The repulsive force configuration enables the increase of DC bias voltage without suffering from the pull-in failure mode. This flexibility in increasing voltage can be employed as a tuning parameter to widen the working frequency range and to improve the robustness of the accelerometer. A lumped parameter model is developed to simulate the response of the microstructure under a combination of electrostatic and dynamic mechanical loading. The electrostatic force is estimated using a finite element simulation. …