1. Micro-Resistor Beam

2. Introduction
The purpose of this model is to show the possibility of coupling thermal, electrical, and structural analysis in one model
The application is to move a beam by conducting a current through it and generate a temperature increase that lead to a displacement through thermal expansion
The COMSOL Multiphysics model makes it possible to estimate the current and temperature increase needed to displace the beam with a given frequency

3. Model Geometry Upper surfaces are ”free” Surface attached to the
base of the device

4. Problem Definition, Electrostatics
DC current balance for
conductive media
Fixed potential to generate
a potential difference DV

5. Problem Definition, Thermal Analysis
Convection conditions
flux out: h(T-Tamb)
Thermal flux balance with the
electric heating as source: Q = k*(abs(grad(V)))2
Fixed temperature T0

6. Problem Definition, Structural Analysis
Force balance with the thermally
induced stress as volume load
Fixed to the base plate

7. Results, Electric Potential Field
Potential profile [V]

8. Results, Temperature Field
Maximum temperature

9. Results, Deformation

10. Conclusions
Steady analysis gives the upper limit for the temperature and displacement
Transient analysis gives the amplitude of the displacement, since the temperature does nor relax completely after one cycle
The model is easily defined and solved in COMSOL Multiphysics