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The constraint doesn't work??

Experimenter
Experimenter

Dear All,

 

I'm working on a blade model of a wind turbine. I want to calculate the mode shape of the model after fixing it at the right end. So I fixed several nodes on the surface. But the boundary condition doesn’t work. Femap gave me the same result as by free free condition, and the surface isn't fixed in the result.

 

I don’t know whether I defined the wrong boundary condition. Theres no problem when I tried to calculate the mode shape with free free condition. Can anyone please help me with it?

 

Thanks in advance!

 

Felix

 

The following are the link to my model and some screen shots

https://www.dropbox.com/s/intatqvjfwsjtb0/bladeeinspannen_ohnedam.modfem?dl=0

 

Define the constrant on the nodes

2.PNG

Fix the nodes

3.PNG

Analysis options

 

7.PNG

Constraint before simulation

6.PNG

 

mode shape after simulation

4.PNG5.PNG

2 REPLIES

Re: The constraint doesn't work??

Phenom
Phenom

Based on the information shown, the most likely problem is that you have a collection of duplicate/coincident nodes which are not connected to your mesh.  You should merge all the nodes.  You may have to switch off "Safe Merge" and/or make sure all the duplicate nodes use the same Output Coordinate System (Modify -> Update Other -> Output Csys) to be able to successfully merge all the duplicate nodes.

 

Another check is to use Window -> Show Entities -> Nodes... Method = ID Constrained to select all the constrained nodes.

Then use the Show Entities again but to show Elements using Method = Using Node and press Previous

(ie. highlight all the elements connected to your constrained nodes).  Clearly the mesh is not connected to the constrained nodes, and you will need the mesh connected to the constrained nodes for your analysis to work.

Re: The constraint doesn't work??

Experimenter
Experimenter

Thanks a lot for your help! Problem solved!