Boundary condition for rotating part

[PEEK]

Hello to all,

i do stress optimization analysis of pump impeller model(40 mm diameter & PEEK material).Since, model is symetric i use one quarter of the model. Considered loads are body loads(10000 rpm) and pressure (0.4 bar). I have a question about boundary conditions.

1. How to constrain in case of symmetry.

2. Impeller is fixed in casing through the centre hole in the impeller, only can roate abt one axis. I tried to constrain by connecting the center of hole with rigid elements (around the hole only in top and bottom surface)and fixed in all directions except rotating axis. But, it produce more stress in the connectting node location.

Is it right. What method of constrain must be used to simulate rotating parts.

Any help would be nice.

Thanks,

PEEK

[Grant]

Do you intend to do a cyclic symmetry analysis or are you just constraining displacements on the two cutting planes?

[PEEK]

Hello,

Thanks for ur reply. I want to do cyclic symmetry analysis and the major consideration is stress in thin parts of the component due to rotation and pressure load.



Thanks,

Prakash

[hakanoz]

i assume, you're using abaqus. in that case, you have constraint the cyclic symmetric boundaries with the key *tie. Since one still doesn't have the possibilty to model cyclic symmetry in ABAQUS/CAE, you have to modify the input-file. In the Input-File with assemblies:

*tie, , cyclic symmetry,name=Constraint-1, adjust=yes
slave_surface, master_surface
*end assembly
*cyclic symmetry model, n=3
0.,0.,0.,0.,0.,1.

the example is for a 1/3 model, with the z-axis as the axis of rotation.
cheers

[PEEK]

Hello,

Sorry. I forget to mention Nastran. I m looking for the same what u said in Abaqus. But, could you please explain further.

thanks,

prakash

[hakanoz]

i'm sorry. i can't help you with nastran, but may be the next thread is a good begin for your problem.

http://www.eng-tips.com/viewthread.c...=132712&page=4

good luck