Drag force computation in single and arrays of micromechanical beams with uniform and arrow shaped width

Nighot, Rohit Prakash and Pandey, Ashok Kumar (2018) Drag force computation in single and arrays of micromechanical beams with uniform and arrow shaped width. Masters thesis, Indian Institute of Technology Hyderabad.

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Abstract

Computation of drag force due to oscillation of a beam or any other solid structure near or away from the fixed surface is very important in controlling the performance of most of the microelec- tromechanical systems(MEMS) and nanoelectromechanical systems(NEMS). Although, there exist many formulations for drag force computations near and away from the fixed bottom surface, they are limited to a single beam. Here, we present a systematic formulation for arriving at a modified formula of drag force and damping coeficient based on experimental results and numerical simula- tion which can be used in computing drag forces in an array of MEMS/NEMS beams. To develop the model, we �rst obtain an approximate analytical model for uniform as well as non-uniform motion of a cantilever beam. Then we develop numerical model and after validating the numerical model with experimental and analytical results for a single beam, we modify the formula for damping coefficient to consider different boundary effects and then apply it to compute damping coefficient in an array of beams. Finally, we also modify the formulas to include damping effect due to lower wall. The developed formula works excellently when the interbeam gaps are small and frequency of vibration is low. However, the percentage error increases with interbeam gap and are found to be in the range of 5%-14%.

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