topic Re: Convergence Issues in Fusion Design, Validate & Document Forum

Convergence Issues

Anonymous — Fri, 06 Mar 2020 12:31:48 GMT

Hi,

I am currently modelling a rocker for a monoshock suspension system on Fusion360, and I am having trouble with mesh convergence.

I have tried multiple models with multiple constraints, and several different adaptive mesh refinement setups, but I cannot get the mesh convergence to work.

See below an example convergence rate and my adaptive mesh refinement settings.

The part is fully constrained.

Hopefully someone has some advice that can solve this issue.

Many thanks,

Andrew

Re: Convergence Issues

TheCADWhisperer — Fri, 06 Mar 2020 12:47:00 GMT

Can you Attach example file here?

Re: Convergence Issues

Anonymous — Fri, 06 Mar 2020 13:05:06 GMT

https://a360.co/2ImWPPp

Here is a link. I would appreciate technical advice rather than the part being fixed, as I have a number of parts experiencing this issue.

Many thanks,

Andrew

Re: Convergence Issues

chrisplyler — Fri, 06 Mar 2020 13:48:16 GMT

First step technical advice: The 360 link provided does allow me to download / open in Fusion. However, once opened, the file does not contain Design History. Did you turn Design History off before saving the file? If you have the file with Design History on, please save it, File>Export it as an Archive (.f3d file) to your computer's local hard drive, then Attach that .f3d file to your next post.

Re: Convergence Issues

TheCADWhisperer — Fri, 06 Mar 2020 14:00:24 GMT

What is your purpose of doing this analysis - what do you want to know as a result of the analysis?

I suspect that I would idealize this for analysis by analyzing only one part at a time rather than as an assembly.

I certainly would not have those Nut components in my analysis.

Re: Convergence Issues

Anonymous — Fri, 06 Mar 2020 15:28:32 GMT

Thanks for the reply's,

File is now attached.

The nuts aren't effecting anything, they are attached as one part to the rod and I am using the nut face as a friction-less constraint. The two bearings (modelled as large cylinders) are done to allow a friction-less constraint to be applied to only part of a surface. If the surface is split, and the friction-less constraint is applied to part of the surface, then there is a large stress value experienced at the edge of the constraint, hence the only way to model the linear/rotational bearings is by including a simplified version of them in the assembly. See attached photo for results of splitting surface.

I am modelling the rocker under a series of dynamic situations, (cornering downforce etc.) Ideally, I would like to run the FEA without the bearings modelled in crudely, but there is no way to constrain it without them.

The image above should help picture the forces and constraints that are applied.

Many thanks,

Andrew

Re: Convergence Issues

Anonymous — Fri, 06 Mar 2020 15:29:22 GMT

I want to know if the part is going to fail under extreme loading.

Re: Convergence Issues

TheCADWhisperer — Fri, 06 Mar 2020 16:58:12 GMT

@Anonymous wrote:
I want to know if the part is going to fail under extreme loading.

What is your criteria of "failure"?

Fracture?

Plastic deformation?

Re: Convergence Issues

Anonymous — Fri, 06 Mar 2020 17:14:16 GMT

I'm looking for a safety factor of between 1.5 and 3. Have you any idea why I am experiencing these mesh convergence issues?