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Robot Structural Analysis

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kmarcinkiewicz
Posts: 14
Registered: ‎01-12-2012
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Robot - Solid Analysis

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01-23-2012 06:01 AM

I have a question regarding solid FEM analysis in Robot.

 

Upon analysing a stair tread, we have found that the obtained direct stresses (sigma xx) match the expected values, however the shear stresses (tau xz) do not take the form expected by the theory (parabolic profile with zero value on the top and bottom faces). The first solution, which comes to mind, is to increase the mesh density, however that does not appear to solve the problem. The stress contour obtained is copied below.

 

I have enclosed the model for reference.

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Rafal.Gaweda
Posts: 5,496
Registered: ‎04-26-2010

Re: Robot - Solid Analysis

01-24-2012 05:45 AM in reply to: kmarcinkiewicz

If it better to generate regular mesh instead of refined one.

Take a look below. Your model ; if you look closer on map near symmetry plane you can see \ imagine there parabolic shape.

 

original.jpg

 

- Shell analogy below - take a look at diagram

 

shell.jpg

 

- if you create this model by extrusion(s) you will obtain regular mesh and the results as follows:

 

regular.jpg

 

- the influence of inclined bottom parts makes these stresses not going down exactly to 0 on bottom edge.

Small example : if you make this model with rectangular shape the stresses will be like that:

 

rect.jpg



Rafal Gaweda
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Contributor
kmarcinkiewicz
Posts: 14
Registered: ‎01-12-2012

Re: Robot - Solid Analysis

01-24-2012 07:58 AM in reply to: Rafal.Gaweda

Thank you, this example explains a LOT!

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