topic Re: SAE Baja Roll Cage Simulation in Fusion Design, Validate & Document Forum

SAE Baja Roll Cage Simulation

Prashant_Jha — Thu, 01 Apr 2021 06:46:40 GMT

Hey everyone

I have designed my roll cage after creating the 3d sketch using pipe command. The body is a joint one. I have used two different types of pipe cross-sections as given in SAE rulebook - primary member ( 1" outer dia. with section thickness 0.12" - shown below in green color) and secondary member (1 " outer dia. with section thickness 0.035 " - shown below in red color).

I have done proper tube notching and all my tube joints are very clean.

Then in the simulation for meshing, I have tried for absolute size from 4-12 mm and in local mesh control, I made the mesh pointer to finest level.

But there are meshing errors. I don't know why?

Is there any way to mesh such structures which consist tubes of different cross-sections in Fusion 360?

meshing errors

isometric view

Re: SAE Baja Roll Cage Simulation

John_Holtz — Thu, 01 Apr 2021 15:30:42 GMT

Hi @Prashant_Jha

As far as the mesher is concerned, your joints are not as clean as you think they are. 🙄

Normally, a model like this would be analyzed using beam elements which means using different software (such as Inventor Nastran) since Fusion 360 does not have beam elements. If Fusion 360 is the only option you have, I suggest that each tube should be a separate body in an assembly. My understanding is that you merged all of the tubes together so that the model is one component, one body. By keeping each tube separate, you can isolate a body to find where the geometry is bad on the part when one body fails to mesh.

Re: SAE Baja Roll Cage Simulation

Prashant_Jha — Thu, 01 Apr 2021 15:43:21 GMT

But keeping every tube as a separate body, won't seem like an unideal situation; as in the real world scenario, the tubes will be welded together to form a single body.

Re: SAE Baja Roll Cage Simulation

John_Holtz — Thu, 01 Apr 2021 15:59:33 GMT

Hi @Prashant_Jha

You define contact in the simulation to simulate the connection between the tubes.

But you can try it with a single body. You just need to look really, really close at the model to see why the meshing thinks the part is intersecting itself. No doubt there is a tolerance problem when you joined all of the tubes together.

Re: SAE Baja Roll Cage Simulation

Prashant_Jha — Thu, 01 Apr 2021 16:05:07 GMT

Ok, Thanks for giving such deep insights.

I will relook at all your suggestions and now I have installed the Nastran also.🙂