Micro-Resistor Beam

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

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

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

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

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

Results, Electric Potential Field Potential profile [V]

Results, Temperature Field Maximum temperature

Results, Deformation

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