Parts going through eachother when load is applied

[EmilyHCH]

Hello,

I'm having an issue where I'm applying a body load on one part and expecting it to compress the part it is touching but instead of compressing the nearby part it is simply going through it without applying any stress on the touching part. Right now, I have surface to surface contact between the two parts and the part I want to see affected by the part with the load is constrained by a rigid body with the encastre boundary condition. How can I get my loaded body to not just travel through neighboring parts but to apply the resulting load on them instead?

Thanks!

 

[EmilyHCH]

I've attached pictures of the progression of what is happening to help describe what I mean.

 

[FEA way]

So you applied body force to one of these parts ? I don’t think it’s a good idea because this will interfere with contact interaction. It would be better to load this part using force or displacement applied to its top surface (via kinematic coupling). You should also refine the mesh and make sure that master-slave assignment is properly done (there are certain requirements that should be considered when choosing master and slave surfaces). Maybe general contact will be better.

 

[EmilyHCH]

I tried using a displacement on the top of the part I want loaded but that is doing the same thing as if I applied the body load. When creating the mesh originally we created a tet mesh for all of our individual parts. What do you suggest we do to make sure our master-slave assignment is done properly? I'm not quite sure how to do it properly to begin with. Master I assumed would be the surface that would be pressing down on the slave. Correct me if I'm wrong.

Thanks,

 

[FEA way]

Most importantly, rigid body surface should be selected as master and it should have less dense mesh.

 

[EmilyHCH]

What about contact between two non rigid bodies

 

[FEA way]

In such case the surface of stiffer body should be master. In addition to these rules, it’s also advised to select larger surface as master.

 

[EmilyHCH]

I tried fixing this issue but the problem is still arising that the part isn't acknowledging the neighboring part and is just moving right through it. General contact was also tried previously but wasn't successful because even though there was a load applied (a significant one too so no risk of being too small) the visualization tab showed us all our parts were blue aka no forces were visibly acting on our assembly.

 

[FEA way]

The mesh should be greatly refined for both contacting parts (denser in case of slave, as I’ve mentioned before). This should help.

And it would be easier to work on this issue with other parts of the model suppressed.

 

[EmilyHCH]

I tried using the refinement rules to make the necessary parts more refined than others. I'm getting a "displacement increment for contact is too big" error and I have been getting it for a while. What can I do to fix this?

 

[EmilyHCH]

It's also giving me an over constraint check, all the interactions I have I personally think are important to establish boundaries and contact so parts don't run into eachother. Do you mind looking at it and seeing what interactions are redundant? I've attached the file below.

 

[FEA way]

Nonconvergence from the beginning of the analysis indicates that rigid body motions are still the problem here.

Please try the following steps:
- suppress all instances apart from the two ferrules (of course you will also have to suppress interactions/BCs and other features assigned to those now missing instances)
- completely fix the bottom of lower ferrule and constrain all DOFs apart from axial translation of the top of upper ferrule (you can do this via kinematic coupling)
- apply small value of prescribed displacement to the top of upper ferrule (with load applied there will be one more RBM left before the contact establihes)
- refine the mesh for both parts
- when you get this working, resume additional instances and features one by one, making sure that the analysis still works after each instance is added