KZ440 road legal cafe racer

I've now made a start on CADing up the frame and the battery to design the traction pack housing, then get the FEA done on the design for the local regs. I wasn't sure how how the box would be built but the ends are coming up way more complex than I anticipated, and making the pack fit in the existing frame is proving challenging (tho not impossible). I had to push outside of the design envelope to use these Lipos, and the ends are way too complex to fold or weld up from sheet so will likely need to be milled. Watch this space.

...officially on the struggle bus

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PK2000 said:
Composites are a surprisingly simple way to make one off, complex, shapes...
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Would love to use CFRP or similar, but my concern is the difficulty involved in modelling and analysing composites where the box mounts up to the frame. FEA on multilayer CFRP is really difficult to get right.
 
Valid points. XXRP isn't isotropic in any aspect, and the manufacturing process' for one offs aren't analysable. So what you do is design for 150% and test to 120%. It' surprisingly easy to do.
 
PK2000 said:
Valid points. XXRP isn't isotropic in any aspect, and the manufacturing process' for one offs aren't analysable. So what you do is design for 150% and test to 120%. It' surprisingly easy to do.
Click to expand...
Thanks PK, I'll have a play around with that too and see if I can get some acceptable results. I may have however stumbled on a way to make this from sheet metal with some internal bracing at the front hardpoints though. I'm goin to experiment with welding up some folded 4mm Al or 2mm SS sheet and see how that comes together as it may be faster than going the CFRP rout. It'll largely depend on how good/bad my welding ends up on the test pieces :D

This is the concept so far for the shell. I'm open to feedback on the idea:

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half shell (the tab at the bottom was for locating a bracket on a 3d print test piece - that wont be in the final):

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Front view of the full shell:


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Rear view of the shell
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Some more progress on the battery box designs this week with the CAD almost wrapped up now. I'll try making this housing from 3mm aluminium sheet, with milled sides and milled rear face plate. The rear face is just too complex to make from sheet and I want to simplify the analysis and manufacturing so will price up a milled piece as the first option before contemplating a CFRP version. The majority of it will be bolted together, but the front will need a bit of basic welding.

Using 5052 H32 sheet for the main body sections; 6061 for the milled sides and rear.

The 20G frontal and 10G rear loading was handled satisfactorily without the side covers so I'm optimistic that the design will broadly meet the VSB14 requirements. I'll post the FEA results once they've been finished up.

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Buildsix said:
Some more progress on the battery box designs this week with the CAD almost wrapped up now. I'll try making this housing from 3mm aluminium sheet, with milled sides and milled rear face plate. The rear face is just too complex to make from sheet and I want to simplify the analysis and manufacturing so will price up a milled piece as the first option before contemplating a CFRP version. The majority of it will be bolted together, but the front will need a bit of basic welding.

Using 5052 H32 sheet for the main body sections; 6061 for the milled sides and rear.

The 20G frontal and 10G rear loading was handled satisfactorily without the side covers so I'm optimistic that the design will broadly meet the VSB14 requirements. I'll post the FEA results once they've been finished up.

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Kawasak-e... Dammit, I like your pun better than mine.
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If I ever have to redo my tank/cover, would it be okay if I steal your idea?
 
The FEA results came out excellent on this design with a fairly good FoS across the board. The mounts and housing show that they can easily withstand a 20G frontal loading (with a 28kg battery load) so that should somewhat offset some of the welding weak points.

The 0.2 appears to be a singularity on an internal corner so it can be discounted.

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