Learning Forum

[tyson.cooney]

Hi, 

I'm attempting to model a packing gland. When the gland is compressed it squashes onto the cable providing a pressure seal. The aim is to apply enough "squash" to create a seal on the cable, but not so much that it ruptures the cable. I have the following issues and questions

1. At 1.5 mm of displacement the gland makes contact with the cable, and the model solves with only some minor warnings, but no errors. At 3.0 mm of displacement I get errors, see below. I have made the suggested adjustments to the model but still receive the errors.

2. Is there a way to identify where element 13485 is? Does AIM progressively remesh the model as the geometry deforms?

3. Is it worth using a neo-hookean material?

4. I have archived the model, but couldn't attach it to this message.

Errors

Physics 1: Mapdl solving has failed.

Physics 1: Initial contact status for Contact 3 is near open. Consider setting the initial contact treatment to Fix unintentional initial gap/overlap in the solver settings, or refer to the Troubleshooting Structural, Thermal, and Electric Conduction Simulations section of the documentation for advice.

 *** ERROR ***
 Element 13485 (type = 1, SOLID186) (and maybe other elements) has       
 become highly distorted.  Excessive distortion of elements is usually   
 a symptom indicating the need for corrective action elsewhere.  Try     
 incrementing the load more slowly (increase the number of substeps or   
 decrease the time step size).  You may need to improve your mesh to     
 obtain elements with better aspect ratios.  Also consider the behavior  
 of materials, contact pairs, and/or constraint equations.  Please rule  
 out other root causes of this failure before attempting rezoning or     
 nonlinear adaptive solutions.  If this message appears in the first     
 iteration of first substep, be sure to perform element shape checking.

Regards

[Charudatta Bandgar]

Hello T-C ,

I have sent you a secure transfer link, where you can send the AIM simulation archive file. 

[Charudatta Bandgar]

Hello  T-C ,

I reviewed your model and this response will enlist all the probable reasons for the partial convergence.

In my opinion, the mesh at the lowermost area of the gland has coarse mesh, by refining the mesh near the contacting faces and higher distortion region might help in solving the problem. You can also further increase the number of substeps for the simulation. 

2. Is there a way to identify where element 13485 is? Does AIM progressively remesh the model as the geometry deforms?

 There is not an inbuilt tool to find a particular element in AIM. Discovery AIM also does not have adaptive meshing, which would progressively refine as the geometry deforms.

3. Is it worth using a neo-hookean material?

 For this problem, I think Neo-Hookean hyperelasticity would help, and it is possible to define it in AIM as well.  

[Charudatta Bandgar]

Hello T-C ,

 

Were you able to get full convergence with suggested changes?

 

Regards.