Microelectro-Mechanical Systems: Modeling and Prototyping
 University of California at San Diego Extension Short Seminar
La Jolla, San Diego, CA
Course Number: EE-40064, Date: October 24, 2000. Time: 9:00 AM-4:00 PM. Location: SMC 115
Instructors: Sam Kassegne, PhD, and Bill Bulat
[Ram International, Collaborative Solutions, Inc, Carlsbad, CA 92008]

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Text Book and References

About the Instructors

How to Enroll: 

Send E-mail

Southern California MEMS Resources

SPAWAR

CSI-ANSYS

UCLA

UCSB

CALTECH

 

Course Content: 

The course will have two sections; one dedicated to the theoretical investigation of the physics governing the behavior of MEMS and a second section that deals with the actual modeling of these systems for a finite element solution.  

Session 1 - Concepts in Modeling and Numerical Prototyping [Instructor: Sam Kassegne]

Micromechanics
  • Scaling Laws in Electrostatics, and Thermal.

Mechanics at Macro Scale – Micro Scale and Nano Scales.

Continuum Mechanics Vs Quantum Mechanics Approaches 

FEA Basics

  • Substructuring

  • Nonlinear Analysis

  • Guyan Reductions

Hybrid Formulations (FEA and BEA)

  • Brief mention of BEA.

  • Brief discussion on Trefftz boundary integral formulations.  

Multi-Physics Analysis Vs Coupled Field Analysis

  • Discuss Multi-Field Finite Elements [e.g., EMT 126 of ANSYS]

  • Some Discussion on Transducer Elements. Equations/discuss the formulations.

  • Analogy Type solutions whereby multiple fields are reduced to single fields.

  • Electrostatics, Electro-magnetism, Thermo- Structural Coupling, Fluidics

  • Show Some Equations and Concepts.

  • Discussion on Sequential Coupling – mildly nonlinear behavior. 

  • Discussion on Recursive Coupling – for highly nonlinear and coupled behavior.

Some Mention of Probabilistic Analysis 
  • Uncertainty in Material Properties and Manufacturing of Components.    

Conclusion

  • Weaknesses in Current State-of-the-art FEA applications
  • Integration of FEA analysis to EDA and CAD environments, etc
  • Future Trends in MEMS Numerical Modeling.

 

Section II - Hands on MEMS FEA Analysis [Instructor: Bill Bulat]

Part 1: Brief introduction to ANSYS GUI:

Preprocessor P

  • Geometry creation

  • Attribute definition/assignment  

Solution Processor

  • Boundary condition specification  

Post-Preprocessor

  • General

  • Time history  

Part 2: 

A)  Exercises:  

1)     Create simple 2D planar electrostatic model, assign electrical boundary conditions, solve, post-process

a)    No structural coupling - pure electrostatic exercise will accustom attendees to electrostatic modeling as a warm-up to coupled field exercises which follow

b)     Determine capacitance  

2)     Reduced order (lumped parameter) modeling (use electromechanical transducer element - EMT126)

a)      Create circuit model (easy, this is basically making a sketch in ANSYS)

b)     Define circuit element attributes (most notably, EMT126 element capacitance versus    displacement)

c)      Perform sine sweep, post-process, plot response versus frequency

d)     Determine transient response to step voltage  

3)     Steady state equilibrium of distributed model with contact ("ESSOLV" command macro)

a)      Review components of preexisting structural model of cantilever beam

b)     Write structural "physics environment" file

c)      Redefine attributes - convert to electrostatic model

d)     Write electrostatic "physics environment" file

e)      Call ESSOLV command macro to automate bi-directional electromechanical coupling.

f)      Post-process electrical and structural results  

B)  Present/Describe/Discuss other Examples

1) Thermoelectric actuation (joule heating => thermal expansion => structural deformation)

2) Magneto structural coupling (magnetic forces => structural motion)

3) Piezoelectric coupled field elements