Need Help with Simulating Space Frame Chassis

[mdmckinley28]

Hello,

I'm working on a designing a space frame chassis and I need help figuring out how to effectively simulate the applied loads. I don't have much experience yet with the simulation software on fusion, so I'm unfamiliar with optimizing for it. As of right now, I go into the simulation workspace, constrain the model, apply the needed loads, and try to have fusion mesh the solid body, but it seems to never be consistent in successfully making the mesh. Even if it does succeed in making the mesh, the study might fail.

My workflow for designing the solid body right now is making 2D and 3D sketches and using the pipe command to make solid (not hollow) pipes, then once I have all of the pipes laid out, shell the entire body to the correct thickness. I know I'm missing many interior features in the pipes by using the shell command, but right now, I'm focusing on speed.

Is there a way to keep a fast workflow and have a more consistent experience trying to use the simulation workspace?

[TheCADWhisperer · Accepted solution]

@mdmckinley28 

Tetrahedral mesh elements do not work well for long skinny geometry and thin geometry (relatively extreme aspect ratio) (beam elements would be better for the frame and thin feature elements for the plates).

You might try this analysis in Autodesk Inventor Professional (you would have to remodel the frame using Frame Generator in Inventor).

[mdmckinley28]

Thank you for the suggestion, I will definitely try it out.

[jonyvanthan]

Hi, the beam-model approach suggested above is worth considering for the overall frame. Your existing centreline sketches would be a useful starting point; shelling the complete joined solid can change the geometry at tube intersections, as you noted.

If you want an option within Fusion, I develop Steel Frame & Weldments Pro. Its Frame Check uses a linear-static 3D beam model for straight members created with the add-in, so it does not need a tetrahedral mesh of the tube walls. You would rebuild members from the sketch paths, assign the actual hollow sections, then set the loads and supports. It reports member stress and deflection and can compare saved load cases.

This is for preliminary frame sizing: joints are idealised as rigid, and it does not analyse local weld/plate stresses, crash behaviour or fatigue. I haven't tested your attached chassis, so I wouldn't claim it fixes that particular model. Are you mainly checking overall stiffness, or stresses around the suspension mounts?