Semiconductors

Semiconductors

MEMS and Lorentz forces

    • Jorge Silva
      Subscriber

      Hi everyone,

       

      I am planning to use ANSYS for MEMS Modal and mechanical simulation.

      I want to simulate a MEMS device that will have an applied AC current that will deflect the MEMS structure due to the Lorentz force caused by the interaction between a Magnetic field and the appllied AC current. Is it possible to simulate the mechanical deflection of a MEMS structure due to a Lorentz force in ANSYS ?

      If this is possible what ANSYS modules are needed for this simulation

      Thank you for your time and knowledge,

       

      Jorge Silva

    • Bill Bulat
      Ansys Employee

      Hi Jorge,

      Yes this is possible however it is not natively exposed in Mechanical so you'll need to use command objects to convert element types so that they use electromagnetostructural DOFs (UX, UY, UZ, AZ, and VOLT):

      I created a small test case to flesh out a procedure (sadly I'm not allowed to send it to you). It's a fixed-fixed electrically conductive beam. A current is sent along the length of the beam - a small voltage drop is associated with the impressed current:

      A lateral (z direction) external B field (1 Tesla) is applied:

      I used a Coupled Field Static analysis system at 2023R1. The beam and surrounding "air" must comprise a single part (conformal mesh, no contact).

      The command objects under the bodies were:

      Both bodies were declared to use the following engineering disciplines:

       

       

      If possible in your production model, extend modeled representation of the electric conductor traces to the external boundaries of the model in such a way that they meet the boundary perpendicularly:

       

      In my test case I assumed that the device is operating in an externally applied magnetic field (e.g., a relatively large and distant PM is creating the field, which I've seen in MEMS mirrors that are actuated by Lorentz forces). I used a DFLX command to define that field on the external surfaces of the model:

       

       

      Create a named selection (with no spaces in the name) comprising the external surfaces of the mesh. Enter the name of that named selection in the NODE field of the DFLX command.

      The net reaction force for this 0.001 m long beam carrying 0.1 A and immersed in a transverse 1 Tesla field should be the product of these three numbers (1e-4 N), which is what was calculated by the model:

      Kind regards,

      Bill

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