3D Design

3D Design

How to choose SolidWorks angle dimensions as parameters

    • adamkovacs1126
      Subscriber

      Hi everyone,


      I would like to run an optimisation study with given angle parameters. I have a complicated geometry created in SolidWorks, but as I am using the Academic version, I had to create a Parasolid file in order to read the geometry in and with this, I lose the opportunity to assign these angles from my SolidWorks sketch as parameters. I attached the following pictures for demonstrating some of the angles I am talking about (for example taking the 20degrees as a parameter and changing it to 15), the SolidWorks sketch I created and the SpaceClaim model itself. Some of these angles create crucial intersection points for the boundary condition of the model and I do not really know how to introduce them as parametric variables without the original sketch.


      Lever with different angles


      Does anyone have any good idea how to achieve this without resketching the whole thing in DesignModeler or SpaceClaim (if that is even a possible solution)?


      Thank you very much in advance,


      Kind regards,


      Adam

    • peteroznewman
      Subscriber

      Hi Adam,


      You don't have to resketch the whole thing, but you can create parameters in either DM or SC to move particular faces of the model.


      Regards,


      Peter

    • adamkovacs1126
      Subscriber

      Dear Peter,


      thanks for your answer. I was also planning to use the Move tool in SpaceClaim to create parameters for a given angle. However, I was surprised to see that after I opened the geometry in SpaceClaim without changing anything and reset the contacts/ joints in Mechanical, my already-working solution failed to work completely with the new CAD format. You may remember the original problem from the previous post: 


      https://forum.ansys.com/forums/topic/help-with-choosing-the-simualtion-type/


      Could you check if the simulation, which you created back then, works the same way with SpaceClaim format? This error is quite annoying, as I use the exact same settings as I used with DesignModeler and yet it gives me a different, non accurate solution. 


      Thanks in advance and kind regards,


      Adam

    • peteroznewman
      Subscriber

      Dear Adam,


      ANSYS products can be annoying at times. SolidWorks and DesignModeler share a common geometry kernel, Parasolid, while SpaceClaim uses the ACIS geometry kernel.  That means when you move geometry from SW to DM, there is no translation of the geometry, only a transfer. But moving geometry from DM or SW to SC means that the geometry data has to be translated from one kernel to a different kernel, and this is where subtle differences in the internal representation of the geometry can cause very small changes that can have a big effect. See this example.


      Another annoying behavior of ANSYS products is that when you have a Mechanical model built on DM geometry, and you open the geometry in SC, all the Mechanical model entities scoped to geometry are broken.  You saw that and suffered the time required to reattach the geometry to the entities. After all that effort, the model didn't solve.  Maybe you made a mistake in the model build, or maybe it won't solve because of a subtle change in the geometry. I don't have time right now to repeat what you have done moving the DM model  to SC, but if you need help getting a parametric version of your geometry solving, I can take a look at that sometime this week.


      Kind regards,


      Peter

    • adamkovacs1126
      Subscriber

      Dear Peter, 


      thanks for the explanation, now the weird behaviour makes full sense. I tried to reset the simulation settings several times, always getting the same non-accurate behaviour: the escape wheel tooth did not want to unlock (although I did not receive any error messages). Then, when I increased both joint load moments to 10 times more, guess what: it worked, obviously with not the same frequency as it was with DM but it unlocked, locked and unlocked again as it was supposed to be!  Now as you said that for SC, the Parasolid geometry is translated and for DM it is not, so I guess I should not take the SC result physically more accurate, should I? 


      I would be more than happy and really thankful if you could help me getting a parametric version of the given angles without a sketch, I already have some ideas but they use the 'Move' function of SC and as I just mentioned now I am not sure I can fully trust the results I am getting with SC.


      Thanks for all the help, 


      Kind regards,


      Adam

    • peteroznewman
      Subscriber

      Dear Adam,  [EDITED]


      I think you can trust the SC simulation. Since the mechanism is dealing with really ramp small angles and frictionless contact, very small changes in those angles can require large changes in moment to get the movement. Did the material density change when you rebuilt the model?


      Have your heard of Robust Design methods?  That is where output of a system changes very little when the inputs vary from nominal. You can consider the angles of the faces of the stops to be design inputs. Variation around the nominal will create a mechanism that runs faster or slower for the same input moment.  There may be a place to put the nominal so that there is less change in the output for the same variation on the input. That is a more robust design than the one where the change in output is greater. This could be part of your study.


      I will try to help you get past each point when you get stuck through this week.


      Good luck,


      Peter

    • adamkovacs1126
      Subscriber

      Dear Peter,


      to answer your question, when I converted to SC from DM, I kept the angles and all other settings the same and there is a really small change in volume (67.368mm3 - 67.38mm3) and mass (5.2884e-004kg - 5.2893e-004kg) between the SC and DM geometries. 


      For start, I was thinking to set the following 5degrees angle as parameter (which is 6degrees on my original solidworks drawing):



      For this, as I cannot get the original base sketch containing the angle itself, I thought of selecting the highlighted parts one by one and rotate them around the center of rotation of the pallet fork (red cross) with the move tool:



      Like this, the parameter becomes the change in degrees to the original value (6 degrees), so for example, if I choose it -1degrees, the 6 degrees lever angle becomes 5 degrees. Is there any easier way to get this 6 degrees as parameter or mine is the only way with SpaceClaim?


      Thanks very much and kind regards,


      Adam

    • peteroznewman
      Subscriber

      Dear Adam,


      SpaceClaim is different from SolidWorks because it doesn't store history. That means that parameters are usually created as changes to the geometry and not absolute values.  You are on the right track.


      Kind regards,


      Peter

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