General Mechanical

General Mechanical

Nonlinear Static Strutural Analysis – Deformation

    • Rádara Colombo Bareta

      Basically, I have this bar with the following forces applied:

      At the bottom, it is supported on the ground in this green surfaces.

      I want the directional deformation on Z axis when only one surface (on the edge) is supporting the bar. 

      But the bar cannot deform in -Z on the other surfaces, because they're supported on the ground.


      So I defined three "Compression Only" supports, and then a "Displacement" (0,0,50)mm on the edge. But the analysis became nonlinear and doesn't converge.

      How can I solve this problem???

    • peteroznewman

      You have one small patch labelled D that has a (0,0,50) mm Displacement. This is a large displacement compared with the length of the bar. That means you need to set Large Deflection to Yes under Analysis Settings. Nonlinear problems also benefit from turning Auto Time Stepping ON and setting the Initial Substeps to 100, Minimum to 10 and Maximum to 1000.

      This might solve completely with those settings, or it may fail and the reason could be the Compression only support.  The issue is Compression only support is a quick and easy way to setup a Frictionless contact without preparing a target surface.  What it does internally is copy the face and use the copy as a rigid target surface. This works well when the deflection is small. But when the deflection is large, the contact surface could slide off the target surface.  The corrective action is to add a part that represents the body that is the "ground" that this bar presses against. Then define frictional contact between the bar and this ground body, which itself is supported by a Fixed Support.

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