Abstract

The objective of this thesis was to develop a Finite Element Model for the Polyimide V-groove actuator (fabricated by T. Ebefors, Sweden). Extensive FEM simulations for this MEMS actuator were performed using ANSYS 5.6. An optimization module was used to improve the performance of the existing design. A substantial improvement in the performance was observed for the proposed design. In short, this research established a methodology that can be extended for modeling and simulation of other MEMS devices. A computer simulated FEM model for heat and deflection analysis was validated for two configurations of the Polyimide V-groove Actuator (i.e. a Serpentine Heater Configuration and a Polysilicon Heater Configuration). Some differences between the simulated and experimental results (reported by T. Ebefors) were noted in the low frequency domain. The role of various parameters including thermal conductivity and wall temperature has been investigated to eliminate these discrepancies. To improve the performance of the actuator, different design geometries were proposed and each design was simulated for various frequencies. Significant performance improvement was observed for the case of "uniform diaphragm thickness at the V-groove bottom". The optimization module of ANSYS was used for optimizing the thickness of the silicon diaphragm (referred to as "single variable optimal design"). Steady state analysis showed that there is an improvement in the deflection and the force developed for the single variable optimal design over T. Ebefors' design. Transient analysis showed improvement in the cooling characteristics of the single variable optimal design over T. Ebefors' design. In the second optimization exercise (referred to as "overall optimization"), all the dimensions of the V-grooves were used as design variables. A three times increase in the deflection was observed in the overall optimal design as compared to the single variable optimal design. Also, there is a three times reduction in the maximum force developed by the overall optimal design. Transient analysis revealed that the overall optimal design has better cooling characteristics compared to the single variable optimal design. Hence, for an application where the applied force is not a critical factor, the "overall optimal design" would be suitable, e.g. if a lightweight mirror is mounted on the end of the actuator, the mirror can be moved through a larger distance. For micro robotics applications, the "optimal design with a single variable" could be useful, where the load carrying capacity of this design is superior.

Library of Congress Subject Headings

Microactuators--Computer simulation; Microactuators--Effect of temperature on--Computer simulation; Structural optimization--Computer simulation; Microelectromechanical systems--Computer simulation; ANSYS (Computer system)

Publication Date

2003

Document Type

Thesis

Student Type

Graduate

Degree Name

Mechanical Engineering (MS)

Department, Program, or Center

Mechanical Engineering (KGCOE)

Advisor

Wayne Walter

Advisor/Committee Member

Satish Kandlikar

Advisor/Committee Member

Hany Ghoneim

Comments

Physical copy available from RIT's Wallace Library at TJ223.A25 K55 2003

Campus

RIT – Main Campus

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