General Mechanical

General Mechanical

Problems in harmonic acoustocs analysis

    • MCK_Pandaleon
      Subscriber

      Hello,

      I have been modelising a transducer and I cannot get results on harmonic acoustics analysis for some reason.

      I have a simplified 3D model that I enclosed (with DesignModeler) in a 3D sphere that has a radius of 20 mm (the transducer has a total length of 4,4mm and a maximum radius of 5,4mm). I want to calculate the far field directivity with a far field acoustic spl mic, observe the sound pressure level and the acoustic pressure of the air and the total deformation of the transducer (piezo+impedance).

      I have 3 contact regions defined : one between the parts of the transducer, and two between the parts of the transducer and the air. All three are generated automatically. I have set the voltages on either side of the piezoelectric element as well as the piezoelectric properties of said element; and defined a displacement on the "emitting" surface of the transducer allow it to have a displacement along the Y axis. I also adequately defined the pressure within the acoustic body (sphere) and added an absorption surface on the outside of it.

      The meshing setting are as follows :

    • Erik Kostson
      Ansys Employee
      Hi

      Can you attach inline images of your model (including part tree), BC, loads, results, error emssages,etc.

      thank you

      Erik
    • MCK_Pandaleon
      Subscriber
      Ah yes sorry,
      I was still editing it, and I hadn't finished before publishing the question
    • Erik Kostson
      Ansys Employee
      No worries - can you also add inline images of your model with BC, loads,.... also state which version (2021 R1?) you are using and if your are using act mem/ or acoustic extensions or not. Also any command snippets.

      Also have in mind that this (piezo acoustics) can be done now in coupled field harmonic 2021 R2 release so without any snippets.

      Thank you

      Erik
    • MCK_Pandaleon
      Subscriber
      Here is the meshed model :
      and here are the details of the displacement settings :
      'face coupleur sup' is the named selection corresponding to the top face of the transducer.
      I am using wb 2020 R2 and the piezo and mems act extension. The loads applied are simple voltages one set at 100 V and the other at 0. I also set the absorption coefficient of the absorption surface at one so as to not have a reflection of the wave.

    • Erik Kostson
      Ansys Employee
      Are you using harmonic acoustic system or?
      Also show all the loads and the whole analysis tree so I can see what you are doing - can not help otherwise.

      As I said also wait/get (not sure if it is yet available as a student ver.) for the 2021 R2 version (coupled field harmonic 2021 R2) where this be much easier to do :).
      Thank you

      Erik
    • MCK_Pandaleon
      Subscriber
      Yes I am, the issue is that I do not have access to that version. Is there not a way to make this work on ANSYS 2020 R2?

    • Erik Kostson
      Ansys Employee
      I am not sure if it can be done with the act extension (I do not use it) - sure one can do it with command snippets (but we can not provide that).
      This video shows how to insert snippets for piezo elements/material and voltage excitation.
      Finally


    • MCK_Pandaleon
      Subscriber
      Hello again ,
      I have seen this work with the piezo and mems extension but for some reason mine simply does not work : I believe there is an issue with my displacement definition but I do not know how exactly to set it. Depending on how it is set the deformations can be very abnormal. I finally found the right configuration and have the right type of deformation for the piezo alone. I haven't been able to find the right disposition when there are multiple components. Could I have a brief explanation of how to define the displacements? The help module is not very detailed.
      No matter what I try, there is a deformation but no pressure change, I cannot visualise any air deformations, is there a possible problem or detail that I overlooked ? I have tried changing the parameters of the acoustic body, ect but I can't find the right solution to observe sound waves in the air.
    • Erik Kostson
      Ansys Employee
      In the piezo/mems extension there is not documentation mentioning the use of harmonic acoustics, hence it can not be guaranteed that it will work, and as I have never used it in that way via harmonic acoustics we can not help - as I said it can be done via command snippets in a harmonic acoustic analysis (this can be done and been used), and the snippets are shown in the video.

      Best of luck

      Erik
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