circular symetry constraint

[olivierpa]

Dear All


I'm working with wildfire 4 and I face a problem with circular symerty constraint


To save time , I used this function but when I check the result I saw the piston is turning arround the axis ,I my mine when we use this function , the parts are lock in rotation


If we have an idea about this probem can you help me


2010-10-05_043711_Doc1.zip


Best regards


OP

 

[solidworm]

i think you have to specify displacement constraints in a cylindrical coordinate system due to the nature of the problem. Cartesian coordinates is not a good choice for a circular symmetry problem. try setting up a cylindrical CS and reference it when defining boundary conditions.

Edited by: solidworm

 

[olivierpa]

I made new analysis with cylindrical coordinate system , I have the same problem

 

[solidworm]

are you sure have you constrained the piston correctly? you have constrained all 6 DOFs on the sides(at theta=0 and theta=90) i guess that results in rigid body motion.

 

[olivierpa]

I made a new analysis using mirror symetry constraint instead cyclic


This time is OK

 

[Kaz Z06]

Alavierpa,

What you are referring to is "cyclic symmetry". When cyclic symmetry is applied, your model will behave exactly as it has from your first result. I would recommend that you select a FEA reference that provides a good explanation of various boundary conditions, how they work and how/when they should be applied. If your system loads your components in a manner that will produce rotational displacement with a symmetrically distributed load, you must use cyclic symmetry if you wish to reduce the size of your model and obtain an accurate result. Have you looked at Mechanica's on-line help concerning symmetry constraints? The on-line help provides enough information to help explain different symmetry BCs.