error in Static Structural simulation for thermal deformation

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  • Last Post 27 June 2019
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AnnaYang posted this 26 June 2019

Hi everyone,

I was trying to solve a steady-state thermal deformation problem in ANSYS Workbench 17.2. 

I solved the steady-state temperature field in Steady-State Thermal and tried to solve the thermal deformation in Static Structural.

The geometry and engineering data are shared, and the solution of Steady-State Thermal will be imported to the setup of Static Structural.

 

There are 13 solid parts and 1 fluid part in the geometry, and the temperature field can be solved and imported to Static Structural as thermal loads.

However, when I tried to solve the deformation in Static Structural, there's always an error:

"An Internal Solution Magnitude Limit Was Exceeded. Please check your Environment for inappropriate load values or insufficient supports."

 

Here is the setting in Static Structural:

1. Imported Load  - Imported body temperature. (Min: 25.106 ; Max: 36.556)

2. Fixed Support or 0 displacement in gravity direction on the bottom face of the whole structure. (Both had been tried)

 

Please give me some suggestions, thank you!

 

------------- added information --------------

1. The geometry includes 13 solid parts and 1 suppressed fluid part.

Since the Elasticity property is needed in Static Structural, the fluid part is suppressed.

 

2. The contact regions, no. 3, 6, 9, 13, 14, 16 and 18 revolve to fluid part, also suppressed.

 

 

3. Fixed Support at bottom face.

 

4. Imported Load - imported body temperature

the source bodies is set by manual way, only import the temperature of solid parts. (1-13)

 

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jj77 posted this 26 June 2019

I would follow the advice the solver gives and check that you sufficient support (e.g., fixed support) so parts do not "fly" away. Also make sure there is contact in between parts.

Also static is a solid structural solver not a cfd solver, so not sure what fluid you have

 

If you post some images of the set up/contacts/supports/..., then someone can see and tell you more.

 

AnnaYang posted this 26 June 2019

Hi jj77,

 

Thank you for replying.

I have set fixed support to try to avoid the "fly" problem, but the error still popped up.

And yes, the fluid part was suppressed at the step of "model" in the Static Structural, it's the reason that model didn't shared.

Thus, all the contacts revolve the fluid region have been suppressed, too.

A test simulation which has a relative simple geometry ( 3  thin Plates : Solid -- Fluid -- Solid ) was done to make sure the suppression won't be a problem. 

 

I will add some images later as you suggested, thank you!

jj77 posted this 26 June 2019

It looks like something is not connected, I would try using inertia relief with small displacement (large deflections off), and then you can see which parts are not connected. Also do a modal analysis on this part as it is with the contact set up you have (without temp. loads), and if you see some 0 Hz modes indicating rigid body movement, and that will tell you what is not supported or connected well..

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AnnaYang posted this 27 June 2019

Hi jj77,

I tried turn on the inertia relief with remote displacement (Y component = 10 mm), and run the model without temperature loads all last night. However, the solution took much more time solving and the error popped out again.

Since it was the first time to use the remote displacement method, I was wondering if the setup was wrong.

Here's the setup:

1. Fixed support at bottom part.

2. remote displacement (Y component = 10 mm) at another small face (circled with red line) which perpendicular to Y direction.

3. inertia relief turned on.

 

jj77 posted this 27 June 2019

I would remove that extra remote displacement and as I said run it in modal analysis with the exact set up, so all contacts you have active and the fixed support and see how it behaves. If there are rigid body modes (0 Hz) that will tell you if something is not connected or supported properly.

 

AnnaYang posted this 27 June 2019

Hi jj77,

Thank you very much. The modal analysis was conducted and it's like you said that there indeed was one part which was not connected properly!

But there was something I don't understand that only the 0 Hz mode I should put my attention to since all the 6 modes are very small ?

And the part didn't get connection well is the rotor of a drive motor, so it should be grab by the stator with magnetic force in the reality.

How to put a non-contact connection between the rotor and stator in the model ?

jj77 posted this 27 June 2019

We get 6 rigid body modes for each mode so to say (since we have 6 dof). SO the rest ones could be the same rotor moving, or rotating most likely in a rigid body rotation.

 

Not sure how the machine is build up, but I assume the rotor is supported and fixed somehow by bearings and the ends of it, and the stator must be also fixed/connected in the casing somehow so you need to provide these supports or contacts between the parts. 

 

At least now you know which parts are not connected/supported well.

 

 

 

 

AnnaYang posted this 27 June 2019

Hi jj77,

A hydrostatic bearing is adopted in this machine, so the bearing is the oil film (fluid part which is suppressed in solid solver).

And yes, there are other parts to fix the spindle, I will check the rest contacts between these parts and try the Static Structural again after that.

Thank you for your suggestions, they are very helpful! 

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