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COMSOL Multiphysics simulation of microresistor beam
Posted Feb 21, 2011, 6:18 a.m. EST 1 Reply
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I had a few questions regarding the physics involved in the example problem of 'microresistor beam' in COMSOL multiphysics 4.0a.
1) Why does the beam deform only upwards.....why not bend down??
2) Is there any specific reason for the unique shape of the fixed ends of the beam?
3) Why is there a temperature gradient in the beam although we have kept the fixed ends at constant temperature of 323K?
4) Why is the deformation less when we consider temperature dependent electric conductivity?
5) Why the name 'microresistor'??
6) What are the applications of this 'microresistor beam'??
Please provide me answers to the above questions.... I have also attached a file of 'microresistor beam' example.
Thanks,
Jean
1) Why does the beam deform only upwards.....why not bend down??
2) Is there any specific reason for the unique shape of the fixed ends of the beam?
3) Why is there a temperature gradient in the beam although we have kept the fixed ends at constant temperature of 323K?
4) Why is the deformation less when we consider temperature dependent electric conductivity?
5) Why the name 'microresistor'??
6) What are the applications of this 'microresistor beam'??
Please provide me answers to the above questions.... I have also attached a file of 'microresistor beam' example.
Thanks,
Jean
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1 Reply Last Post Feb 21, 2011, 8:58 a.m. EST
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Posted:
1 decade ago
1/ Because of the way the legs connect to the beam part it would take a lot more energy for the beam to bend downward or sideways than upward.
2/ Somebody designed it that way, don't read too much into it.
3/ There's a heat source in the volume (Joule heating), so the structure heats up. That heat source is largest in the beam part because the current density is the highest. Now, the bottom of the legs are held at a known temperature so they can't heat up. The temperature field must be continuous, so there's a gradient in the temperature field.
4/ The deformations are caused by Joule heating, Joule heating is proportional to the electric conductivity, and the electric conductivity decreases with temperature.
5/ It's a resistor and it's tiny...
6/ It's a type of MEMS actuator. It could be used to move/animate any kind of microscopic device.
2/ Somebody designed it that way, don't read too much into it.
3/ There's a heat source in the volume (Joule heating), so the structure heats up. That heat source is largest in the beam part because the current density is the highest. Now, the bottom of the legs are held at a known temperature so they can't heat up. The temperature field must be continuous, so there's a gradient in the temperature field.
4/ The deformations are caused by Joule heating, Joule heating is proportional to the electric conductivity, and the electric conductivity decreases with temperature.
5/ It's a resistor and it's tiny...
6/ It's a type of MEMS actuator. It could be used to move/animate any kind of microscopic device.