General Mechanical

General Mechanical

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Sliding mechanism analysis for stability

    • balaji.bp
      Subscriber

      Hello all, I am working on one sliding mechanism problem where two silde on both sides are carrying a certain weght of 50 Kg which i have attched as point mass as shown in below fig, I contact is firctional with 0.02 coff. i have tried this problem in two approaches in first i have given displacement to two slides 100 mm and second i considered expanded stituation (extrem point withount any displacement) and solved but in both the cases i am getting different results with huge difference. Why?

    • peteroznewman
      Subscriber

      Please show what geometry was scoped to in the 100 mm displacement.  If you scoped an end face of the slides, that creates a support that is not present in the simulation with the slides positioned at 100 mm without any displacement support, so I would expect to see a significant difference in results.  The repositioning method is closer to the correct boundary conditions for this problem.

    • balaji.bp
      Subscriber

       

       

       

       

      Hello Sir, thanks for the reply.

      Yess in first approach I have scoped the end faces of two slides for applying 100 mm displacement.In this I have applied X displacement to end surfaces and Y and Z kept zero may be because of that its happening.If it so then what is the way to apply motion and see the end stresses in both the analysis having less difference)

       

      In both the cases point mass is scoped to the 4 holes surfacse which are present on both the slides.

       

      Thanks in advance 

       

       

       

       

    • peteroznewman
      Subscriber

      Delete the Displacement boundary condition on the two end faces of the slides. That is causing an unrealistic support condition.

      Select the two end faces and create a Remote Displacement. Make sure the Behavior is Deformable. Now you can assign an X displacement to the control node between the two end faces, leaving the other five degrees of freedom set to Free. This will move the rails along the slide without any extra constraints except for the X displacement of a single node.

    • balaji.bp
      Subscriber

       

       

      Hello sir, really thanks for your reply.

      I did apply the boundary condition as you suggeseted but the results i am getting are very weird which can be seen in above images, Stress is almost 5000 MPa. 

      Please let me know what mistake I am doing.

    • peteroznewman
      Subscriber

      You need the slides to be attached to a structure such as a drawer.  A quick way to do that is to change the remote point supporting the mass to be rigid instead of deformable, but it is more accurate to model the drawer.

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