Do high-end skidplates need to be made of carbon fiber? Lets find out!
OpenDocument Spreadsheet - 17.19 kB - 04/25/2019 at 15:48
Microsoft Office - OOXML - Spreadsheet - 6.02 kB - 04/25/2019 at 15:48
Step version of 1983 Xt200 Skidplate
stp - 110.34 kB - 04/04/2019 at 00:45
BMW F650GS 2006 Skidplate reference, needs to be updated with Solidworks model version
3dm - 1.29 MB - 04/01/2019 at 15:26
3D Design in Rhino for 1983 Yamaha XT200
3dm - 1.32 MB - 04/01/2019 at 15:24
We coated the molds in resin to seal them, we can apply wax or another release agent.
You can see how the lines have smoothed and cracks have filled in.
All molds were milled out.
Verifying standoff with insert:
A pocket for the overhang insert was removed and the surface sanded:
We tested for deflection and measured samples:
See documentation spreadsheet: "Coupon Testing"
Our testing rig for deflection:
Measuring the weight:
Crunching the numbers:
The BMW F650gs Skidplate and mold are also ready for physical evaluation.
The flattened cut sheet needs verification, it's difficult to flatten a complex surface with double curvature while minimizing errors.
Our sample composites are starting to improve with much better surface finish and strength. The laser wasn't able to cut our samples into strips.
Jump shears also didn't work.
Fortunately some table mounted draw shears did work, providing clean cuts easily.
The design of the skidplate has been updated and we are getting significantly higher rigidity in simulations; cut-sheets and molds have been designed for verification.
The CNC mill has a Z axis travel limit of three inches so the mold has been split.
The extracted and flattened surface for use in the lasercutter needs verification.
Our latest samples have been turning out well.
Unfortunately the lasercutter cannot (easily) cut through the material after it is turned into a proper composite. We will need to cut with other tools to test in our Instron machine.
Toviah added a notch to see if it would improve deflection for the XT200 Skidplate.
Based off our simulation we are trying for 25 percent increase in rigidity over the initial prototype.
And with two ridges:
If you look at the scales we are seeing a significant increase in stiffness, something like a 21% increase over the current prototype.
There are animation files too which will be added as available.
After removing some material around the exhaust I forgot to account for and moving a mount point we got the skidplate for the XT200 mounted and some miles logged. No bad vibrations and a close fit.
It actually blends in with the bike due to its low profile.
We might use a sheet metal insert to oven cure our next part to avoid heat deformation ahead of use.
You can barely see it!
We are adding contours and a lip network to increase rigidity and then plan on CNCing out a foam mold for the next iteration while working on the BMW skidplate which will be a little more complicated. We have run some basic simulations and will share some visualizations when we get the chance.
We removed the part from the mold today.
The female side of the mold was pretty well stuck so we had to break it apart.
The insert block for the overhang hook was also really stuck in there.
After cleaning up the edges this seems like a pretty usable part. Its definitely too thin and the surface finish is far from perfect but things are looking good.
The front mount point will need to be drilled out but the pilot hole came out clean.
Now to double check that it fits on the bike and see how it responds to loads!
To make our cutsheets for the skidplate I unrolled our digital model, this will be included in the files section.
It's not very complicated but annoying to cut out with scissors. A laser seemed like it should do the trick.... And yes, we're including the hole.
Each sheet takes about a minute and a half to completely cut out. It takes much longer to just get it off the bolt.
We are able to get very precise cuts. Burns could probably be minimized by going a little faster, I had the settings up pretty high. Ahem, shameless plug:
Then actual lay-up began.
Some cut-sheets got messed up because of tape, going to have to minimize that in the future.
Here you can see some kinda ugly patch-working:
The outer most layer is 50/50 Carbon and Kevlar. Kevlar doesn't like UV light very much but since this is a semi-disposable component I'm going to give it a shot to see if it helps with scratches and such. I also added the Wallfacer Design logo, because I can.
The end tab was folded over into the insert and then the top half of the mold was lined up and clamped down as hard as we could.
To help with clamping force in the future we should cut the mold exterior faces flat.
We did a poor job of recording our first couple of FEA simulations so hold tight for those.
The XT200's skidplate has simpler curvature so is being attempted first.
At first I used the pilot curve to cut a bunch of wooden templates and then attach them together to make a positive mold.
Since we still don't have the vacuum system working I changed my mind and made a two part blue foam mold.
It has a slot for an insert block for the overhang tab that connects near the swing-arm connection.