Improving the Mesh Quality for SAE BAJA Roll Cage

In pratice, you can not do a "good" mesh with a good value for every criteria.

Take some criteria as important for you, like jacobian, aspect ratio,...

Another point: split your geometry and do fine mesh within critical area.

So, if at all at the end, i don't get zero elements violating the thresholds, then how to run the analysis using Opti struct solver as it gives error message 'Problem while element quality check' even if some elements are are violating the threshold. 

You mesh, as show in your picture, is NOT so good. You have to improve alot to get a good mesh.

Here's my 10-minute-mesh to give you some idea.

Can you please help me by posting a video that how have you achieved this much fin mesh starting from the geometry cleanup?

It would be of great help to me. Please, Please help me. 

I have no time to make a video, sorry. But if you have any question, I could give you some ideas.

Can you share your HM model?

Hi, I have attached mine surface model, it is unmeshed one, can you please help me in showing how to mesh the joint where five tubes are welded?

It would be of great help to me.

Split your surfaces to better control the mesh.

Begin with fine mesh:

And you got:

Have a look at my modified model in attachment.

Thanks for your guidance.