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Dynamics Modeling of new Scratch-drive Actuators with Bounce back Mechanism (BSDA)

Attarzadeh, Mohammad Ali | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45740 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Vossughi, Gholamreza; Meghdari, Ali
  7. Abstract:
  8. In recent decades, micro-electromechanical systems – MEMS – havefound extensive applications in applied science and engineering. One of the most popular MEMS actuatorsis micro Scratch Drive Actuator (SDA), which can be used in various applications, for instance: precision positioning, micro-chip displacement and rotating micromotors. Their outstanding capabilities such as: high controllability, precise step displacement, vast transportation domain and large force relative to their small size, have made them popular among researchers. Recently, a new generation of SDA is introduced, known as Bounce-back Scratch Drive Actuator or BSDA, which is fundamentally different in motion generation from its predecessors. Dynamics modeling, characterization and calculation of step displacementof this novel actuator can provide conscious and sharp-sighted utilizations. However, unfortunately there is no appropriate analytical study available surveying problem precisely and describing how actuator produces backward motion instead of forward motion. In this study, firstly, all necessary degrees of freedom to describe system and external effective forces such as: electrostatic, squeezed film damping, Van der Waals, Casimir and Impact were distinguished. Moreover, a new, closed-form, powerful model were introduced, in order to effectively investigate squeeze film damping force in micromechanical devices, which has the ability to consider compressible flow conditions, structural flexibility and unknown deflection. Secondly, movement in each cycle was divided into two phases and equations of motion were extracted in each phase seprately, by utilizing Hamilton’s Least Action principle. Subsequently, by using Bubnov-Galerkin weighted residual method, the governing beam nonlinear PDE was substituted with a set of nonlinear ODEs regarding to its three different boundary conditions or configurations. The obtained equations of motion were solved numerically by MATLAB Simulink time-integration solver. In addition, plate-tip bouncing phenomenon were modeled and effectively reduced through proposed method. Results clearly illustrate the effect of bushing dynamics in actuator’s pull-in voltage and overall dynamics.Furthermore, by using proposed dynamic model, step- size movement was predicted with reasonable accuracy in comparison to experimental works in literature
  9. Keywords:
  10. Dynamic Modeling ; Squeeze Film Damping ; Reduced Order Model ; Electrostatic Actuation ; Contact Problem ; Impact

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