Radial displacement of rotating cylinder

[BoomerSooner7]

Hello,

I am performing a static study in SW '10 to determine the max. radial displacement of a rotating piston rigidly attached to a shaft rotating at 3600 RPM. I actually have the piston and shaft drawn as one part and have two bearing journal surfaces on the shaft where I am applying fixtures that only the shaft to rotate around its axis. I applied a angular velocity of 60 hz. I am not confident in the results I am seeing for displacement on the circumfrance of the piston, possibly due to incorrect setup. Attached is a .jpg of the shaft. It is a 3" shaft with an 11" piston and it's saying the max deflection on the perimeter is around .25".

 

[kellnerp]

You have displacement under your radial constraints. That is surprising. Have you checked the material properties?

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[BoomerSooner7]

I assigned plain carbon steel from Solidworks materials. When I apply a fixed constraint on the two cylindrical surfaces it yields much more acceptable results with a max. displacement of .00013". I assumed that fixing the bearing surfaces instead of constraining radial, translational defeated the purpose of a radial displacement due to centrifugal forces?? I dunno.

 

[kellnerp]

Oh, he says as the lights come on!

You realize that the math model, the nodes and elements don't actually rotate. A radial acceleration is applied. Since you are plotting URes you are not seeing radial displacement at all. You are seeing circumferential displacement. Turn on a vector plot when you do your displacement plot. I'll betcha that the arrows are tangential. That is how you can have such a huge displacement under a radial constraint where displacement is supposed to be zero.

To put it another way, your model is underconstrained and is flying off into space in a rotational kind of way.

TOP
CSWP, BSSE

http://www.engtran.com

http://www.niswug.org

http://www.linkedin.com/in/engineeringtransport

"Node news is good news."

 

[BoomerSooner7]

Makes total sense now, since someone has explained it to me. Different subject here but do you have any recommendations on a good FEM book, can be either Solidworks simulation specific or not.

thanks.

 

[kellnerp]

My Basic FEA Library from beginner to difficult

Building Better Products with Finite Element Analysis, Vince Adams and Abraham Askenazi, Onward Press, 1999 (out of print)

Concepts and Applications of Finite Element Analysis, Robert Cook, John Wiley and Sons, 1989

Finite Element Procedures in Engineering Analysis, Klaus-Jurgen Bathe, Prentice Hall, 1982

Finite Element Handbook, Hayrettin Kardestuncer, McGraw Hill, 1987


TOP
CSWP, BSSE

http://www.engtran.com

http://www.niswug.org

http://www.linkedin.com/in/engineeringtransport

"Node news is good news."