Rigid link for assembly analysis

[AS_10540676]

 Hello All, 

In the attached snap of my assembly, i would like to constraint center point of half circular surface. For that, i was attempting to create rigid link between center point and surface of half circle. and added displacement at center point. Can you please suggest is this a right way to do it? 

Rigid link

Thanks 

Ankur Shah

[AS_10540676]

@SweetPeasHub 

Can you please help in this query? 

Can you please share the best procedure to define contacts  and constraints?

[SweetPeasHub]

It is unclear to me what exactly the constraint is trying to accomplish, however the reason it will not work as shown is there is no element connected to the center point. Add a spring to ground at the point with low stiffness, or add a low stiffness spring from there to some arbitrary point on the model. In the image there is a weighted link not a rigid link. An assumption of rigid may not be correct. If the stress near this bolt pattern is not important then this is OK. If the stress near this bolt pattern is important then the boundary condition should include part of the mating components. This is due to St Venant's principal. (you have to have boundary conditions far enough away from area of interest so the approximation error is negligible)

-regards

[AS_10540676]

@SweetPeasHub 

Thanks for your reply. 

Half circular flange will have small metal wheels mounted on holes around the flange. So yes i would like to see if that flange will be under acceptable stress? 

To have this, if i create a spring with low stiffness like 10N/mm connecting center point of half circle flange to half circle flange surface as shown in attached image, do you think it will work?

Also i came across another issue with pin joint as shown in problem 2 attached image. Can you please advise what should be my interfaces and constraint to analyze this situation? There is a frame in between blue lugs on both sides locked with pin. Nothing welded here. Middle frame will be in position by 2 of these type of arrangement on both sides. 

Appreciate your help.

[SweetPeasHub]

Problem1. Yes, that spring and then adding the rigid or weighted link from the center point to the holes seems like it is OK to me. Keep in mind the wheel strength/stiffness would likely improve/reduce stress in the flange as it is a kind of reinforcement to the flange. It looks like a conservative assumption to exclude the wheels. Make sure you think about the center point constraint, that it behaves like a wheel. (for example if the wheel is on ice or greasy surface, the only constraint might be normal to the ground plane "Z" with all other translations and rotations free (movement arrested by the flange, rather than the point constraint)
Problem2, I think there are several similar examples in the community, but to be brief you might need another of these springs to stop movement along the pin axis.
Idealization-of-Dowel-pins-in-Creo-Simulate 

Creo-Simulate-contact-analysis 

Analysis/Pinned-joint-idealization 

Weighted-links-in-the-place-of-Mechanism-links 

Thanks for promoting my answer.

-regards

[AS_10540676]

@SweetPeasHub 

Apologies, but can you please advise, how do you mean by "brief you might need another of these springs to stop movement along the pin axis".

What currently i have done is added 1. frictionless contact between pin's outer face and lug's inner face, 2. pin's outer face and intermediate frame's female  hole 3. contact between inner face of blue lug and face of intermediate frame. 

But with this it looks like the stresses are not being transferred to the pin, as i want to ensure diameter of the pin is correct or not. Also, i am not able to find the way to restrict the movement of pin axially.

Can you please help with this? 

Thanks 

[SweetPeasHub]

2nd article, here is a screenshot of what I mean for axial constraint. Please read those other questions through that I gave the link to. These are very similar situations to yours.

[AS_10540676]

@SweetPeasHub 

Hello sir, Once again thank you so much for your guidance.

For Large deformation calculation, weighted link and springs as well as rigid links are failing the simulation. Can you please advise, am i doing something incorrectly? Also, if i place spring with creating points on edge, also it gives warning and then simulation fails. 

Can you please advise, if any other way to perform simulation? Beam elements are also not working in this case.

[AS_10540676]

@skunks Can you please share your view on it?

[SweetPeasHub]

From the image it is hard to tell why you need LDA, but that is much more limiting. No beams, No to ground springs, Use caution with weighted links.

https://support.ptc.com/help/creo/creo_pma/r10.0/usascii/?utm_source=creo/&index.html#page/simulate/simulate/lg_deform_loadtype.html

This is the way for LDA. Simple point to point spring 10N/mm, + rigid link. Please try to understand the meaning of the warnings so you know when it is OK to ignore the warning. In this case there could be a conflict between the rigid link and the constraint, but there is not a conflict so we ignore the warning.

[AS_10540676]

@SweetPeasHub 

Thanks  a lot for your help. 

Can you please explain bit more about rigid link, it should be from PCD holes to its edge of half circle or center of halfcircle?

[SweetPeasHub]

[SweetPeasHub]

Image for problem2

[AS_10540676]

@SweetPeasHub @skunks 

Hello Team, 

Thanks for your help again.

My analysis is failing without giving any error. Can you please advise, where it went wrong? I have attached error snaps.

Thanks in advance.