New in Mecway- help needed

gabgab
Dear all,
I'm very new to Mecway and I need to be pushed to achieve my "project". I'm a biologist and I'm trying to perform a FEM analysis on a root of a plant. I need to model it after bending stress that poses it curved of 90° respect perpendicularity to ground (the root forms a "L"). I have the diameters of 15 samples (like rings) of root that cover a lenght of 15 cm. These diameters come from two roots that have temporal differences (and also diameter differences) in the treatment and I would like to create a model indicating me which are the most stressed sectors.

I tried to consider the root as a sort of crane frame (following a tutorial), performing a dynamic response 2D and trying to displace the root from vertical to L shape.
But I think it is not the right way.
Contemporary, I tried to draw directly the root in L shape, but even in this case I don't get any good idea and result.

Please, any suggestion is super-welcome.

Thanks a lot in advance!
Gab

Comments

  • VictorVictor
    Here's an example bending an initially straight strip through 90 degrees. It uses time-dependent pressure acting as a force couple but you could also do it using time-dependent displacement.

    It needs to be a non-linear analysis to capture the large rotation through 90 degrees and I think inertia isn't important so I've used Nonlinear Static 3D.
  • gabgab
    edited October 2018
    Hi Victor, thanks for your suggestions. Your example is something interesting for me.
    May be I give you more details to get as much suggestion I can: I whish to obtain a model describing the distribution of the longitudinal mechanical forces along the root (something like the image I attached), in order to describe the differences for the two timepoints I have. The only data I have are related to the lenght of the root (15 cm divided in 15 sectors) and diameters of the root (each sector a different diameter....you can find them in the .xls file).
    Other info I have are related to wood that is considered to be mechanically isotropic (Young's modulus of 5GPa, Poisson's Coefficient of 0.3) and a density of 1000kg/m3.
    Thanks a lot again and I would be happy to receive other inputs.
    Gab

  • VictorVictor
    Being only 15 values and new to Mecway, it might be easiest to make the mesh by hand and enter all those values by clicking nodes. However, if you're going to do this multiple times, you could make the mesh definition in the spreadsheet and export as CSV or copy/paste into a text file. There are some simple file formats like .inp (nodes and optionally elements) and .xyz (nodes only) that are quite easy to generate and which Mecway can read.

    In either case, I would start with a 2D mesh of the section from the longitudinal axis to the surface and then revolve that to form the cylinder. Also, start with quadratic elements for smooth curves when you revolve and refine it.
  • gabgab
    edited November 2018
    Dear Victor,
    thanks a lot for all suggestions you gave, they were precious while building the model.
    Now I have another question about the output of the analysis. Is there a way of getting the mean stress of the longitudinal mechanical forces in a specific section of the model?
    Through the "new table" tool can I get values of a selected portion of elements?

    Thanks a lot again for availability,
    Gab
  • VictorVictor
    In version 10 which is now in beta, you could do a surface integral (Solution -> Surface integral) over the surface of the section, then divide by its area to obtain mean normal stress.

    In version 9, you could make a very thin section and use Solution -> Mean to average the stress over that thin volume.

    The table can show values for elements in components or element selections that were defined before solving. They'll be available to select in the list in the top middle of the Table window.
Sign In or Register to comment.

Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!

Sign In Register