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What is your advice on size disparities in meshes in explicit dynamics?

    • wyatt
      Subscriber

      Hello learning forum!

      I have questions regarding my meshes involved in an interaction between a rotating cylinder sample and a small tool. Also if you have any comments as to the way I am approaching this simulation, please feel free to provide your input!

      I have attempted to section my models to generate a better hex mesh.

      My concern is that the mesh of my tool is finer than my sample. Also, my sample does not have layers at the surface of interaction. Should I consider layers where the sample would be machined?

      As a side note, I have the student copy of Ansys and the scale of this analysis is quite small. I am primarily interested in the stresses, strains, and forces in the tool.

      I would appreciate your input. ?

    • peteroznewman
      Subscriber
      @wyatt, nAre you plotting Characteristic Length (CL) in the Mesh Metric? The minimum value of CL controls the maximum time step, which determines how long you have to wait for the solution. See my comments in this discussion.n

      @peteroznewman Sir I have searched so many times for accepted answer but I didn't get it. once again sorry for that I have also tried @Rob sir's approach but still not finding yet. May be I have started with new discussion so may be this is not occurring now, I am trying here my doubt as Ask a Question according to @Kremella sir's guidance.@peteroznewman Sir i have tried with 12 mm tool travel nut still my tool is not travellingand actually distance between that two vertex is 6.8 mm which you have mentioned in last discussion.https://us.v-cdn.net/6032193/uploads/1W96E2KDRI3H/img-20201020-wa0029.jpghere i am also attaching my ANSYS 2019 file. please guide me why this things is happeninghttps://us.v-cdn.net/6032193/uploads/JAYTXB21YVPK/rp-2-2812mm-29.zipif you find any mistake please change it and send with me for better understanding.Please answer as soon possible.Give regardsMihir Aminhttps://forum.ansys.com/discussion/21391/thermal-aspects-during-turning-operation

      The size disparity itself is not a problem. What matters is the gradients in the solution and whether the elements are small enough to capture the gradient. If the stress jumps up a significant amount from element to element, then the elements are too large.nIf the smallest elements are in the tool, it will not greatly impact the solution time if you double the number of elements in the workpiece, but I understand you have to stay under the Student limit. nPerhaps you can use Symmetry?n
    • wyatt
      Subscriber
      Ok, thank you, !nI was plotting element quality in the mesh metric. I have attached the characteristic length mesh metric.nI will try using symmetry and see how things turn out. (pun not intended)nWould you recommend refining the mesh on the workpiece, and if so, how would you go about it? nI will start a new thread as more questions come up, but as a side note: the RPM that I plan on applying to the workpiece is 500. One revolution would be .125 seconds. Explicit dynamic analysis (from what I have seen) last about 100-1000x less than this. So I may limit the size of the sample to the amount of time it interacts. I have more questions surrounding this, which I will ask in a new thread. nn
    • peteroznewman
      Subscriber
      Insert Mesh controls to make smaller elements on the workpiece. There are many ways to get a similar result. Inflation is one tool to get several thin layers of elements off the surface. Pick the body in the first field and pick the face of the workpiece as the Boundary. You can also use a Size mesh control and pick the circular edges to put more elements along those edges.nIt's good practice to start a new discussion when you ask questions on a different topic since that helps others who are searching for help to find it more easily.n
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