10 Replies Latest reply on Aug 15, 2014 1:20 PM by James Riddell

    FEA Study Support - Structural Member and Solid Bodies

    Douglas Maves

      I have been trying to run a simulation study on a structure for a project; the structure will be used to support a pan mold from a center pivot column but need to have very minimal deflection or sag. I need to verify material sizes to ensure my design meets our criteria; however I am having issues when trying to run the study for this structure. It is a combination of structural members (i-beams and tubing) as well as standard extrustions (mounting plate). The structure is to be bolted to a bearing that will be attached to the center pivot column and I have been trying to apply a load of 700lbs to the flat portion of the model but am having issues with it not terminating or blowing up? Any help?

       

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        • Re: FEA Study Support - Structural Member and Solid Bodies
          Jared Conway

          where are you stuck?

          handling the bearing? have you checked the bearing examples?

          mixed meshing? have you checked the mixed mesh tutorials?

           

          my suggestion, start simple, usually where your restraint is and with a gravity load and slowly add components. if something doesn't work, at least you;'ll know what you added to cause the issue so it is easy to troubleshoot

            • Re: FEA Study Support - Structural Member and Solid Bodies
              Douglas Maves

              Attached is the part I am attempting to run FEA on to determine if the structure (I-beam) size I have chosen will keep deflection to a minimum due to the weight of the mold part it is supporting. I will also need to know if the mounting ring material is sufficient enough to eliminate deflection as well.

                • Re: FEA Study Support - Structural Member and Solid Bodies
                  Jared Conway

                  what problem are you running into? an error? just getting started?

                    • Re: FEA Study Support - Structural Member and Solid Bodies
                      Douglas Maves

                      I am fairly new to the simulation/FEA studies in SW; I am unable to apply the correct fixtures to make the model stable to complete the simulation. I am also running into issues when applying additional connections between the solid bodies (mounting ring/plate) and the structural members (square tubing).

                       

                      Would it be a better option to break down the part and perform a study on just the I-beams supporting the mold weight and fix them on the faces that will be welded to the sq. tubing, then perform a separate study on just the sq. tubing and mounting ring/plate using a remote load/mass?

                        • Re: FEA Study Support - Structural Member and Solid Bodies
                          Nicholas Luyster

                          Hi Douglas,

                           

                          In this case, you have 20 bodies and this is a lot to start out with.  I recommend that you eliminate all but 3 or 4 bodies and then run a simple simulation to check for faulty connections.   After you do this, add a few more bodies and run another simple simulation. Keep doing this until all the bodies have been added in. Try not to be concerned with the accuracy of the loads or the fixtures as your adding bodies. - A conventional fixed geometry fixture and force load is all you'll need.  After you add all the bodies in and all the connections are behaving properly, then start creating more accurate loads and fixtures.

                           

                          I'm guessing connections you'll want to create will be bonded Beam to Face Contact Sets.  Please see attached pictures.1 for douglas.png2 for douglas.png

                           

                          I don't know how the structure will be held in place but I'm guessing just a fixed geometry fixture may be adequate if placed properly. 

                           

                          All the best,

                           

                          Nick

                          SolidWorks Simulation Training

                            • Re: FEA Study Support - Structural Member and Solid Bodies
                              Jared Conway

                              I second this.

                               

                              go through all the tutorials and if you have access, a training manual.

                               

                              then start with a couple of parts, get those to work and then when you get stuck with the next part, post your status here.

                              • Re: FEA Study Support - Structural Member and Solid Bodies
                                Douglas Maves

                                I went ahead and performed individual FEA on each beam by fixing it on one end and applying a load of 150lbs to the beam, however, this resulted in a deflection of 0.241" for the longest beam member. Is doing this accurate simulation for my part, or do I need to apply point loads on the beam where the plate will be supported? The plate will be supported by jacking bolts protruding from the i beams.

                                03.JPG

                                 

                                 

                                I eliminated the top plate and ran a study on just beams and was able to get a deflection; however I am not sure if this is accurate as it does not account for the rigidity of the 1/4" plate and the deflection is different than the individual FEA I ran. I used fixed geometry and applied the load (150lbs each) to the beams as shown in the picture below. Again, is applying point loads at the point of contact with the plate the direction I need to go?

                                01.JPG04.JPG

                                 

                                I tried to run FEA on the model with the 1/4" plate modeled in, with small boss features to represent the jacking/support bolts, but I run into an issue as it says the model is unstable. The 1/4" plate will only be sitting on top of the i beams, and not mechanically fixed or bonded. I have applied a 'no penetration' contact set between the beams and the boss features on the underside of the plate. I applied the load to the top of the plate, representing the weight of the bar stock and finished part weight; I used the same fixed geometry as before, see picture below:

                                02.JPG

                                What contact sets or fixtures do I need to apply to keep the model stable for this simulation? I didn't think I would apply a bonded contact set between the plate and boss features given that the plate is free floating and will be held in place by tabs to keep it from shifting on the beams) do i need to model these tabs and apply contact sets?

                                  • Re: FEA Study Support - Structural Member and Solid Bodies
                                    Jared Conway

                                    start with bonded and see where it gets you

                                    once you get through that you'll have a really complicated analysis on your hands, what holds the plate on the beams on the physical world? and how does it not being connected relate to your analysis goals?

                                     

                                    to note, the method that nick and I suggested, you are following it, but sometime to add, we aren't suggesting that stopping at the beams only was the ending point, it was merely the starting point so that you knew where your contacts..etc were no longer working which is what you found

                        • Re: FEA Study Support - Structural Member and Solid Bodies
                          James Riddell

                          Douglas,

                          I've had luck working with contact sets (no penetration) that are tangent to a surface.  However, if you run them as strictly linear you will see extremely high stress.  I've had better luck running these as non-linear static analysis.  Also, I'd suggest you explore the sliding constraints. 

                           

                          How much deflection is too much?  You might already be in non-linear territory already.  Have you done a hand-calc estimation of deflection on one beam member yet?

                           

                          If it is too big to run you could likely set this up as a symmetry problem (don't forget to halve your load).