Seam welding chassis, Video on how effective it is Options

[TravisNeff]

Interesting watch.

https://www.youtube.com/watch?v=RfDPUD-RhMM...s7x-uda9r9hMtTQ



https://www.youtube.com/watch?v=RfDPUD-RhMM

[tperazzo]

This week I did some experimentation with the forces in the front strut bar. I thought the results were quite surprising! Maybe not very relevant to the 914 because it already has better front strut support than the 911.

1) Increased torsional rigidity is about 10%
2) Max load in the horizontal bar was measured at 70 lbs
3) The loads alternate between tension and compression
4) Changes in camber are very small with or without the strut bar


This video is a bit long, but I did everything I could to make the strut brace look good. At the end of the day it didn't impress me much.

https://youtu.be/QjGYaeYew8s

[jd74914]

1) Increased torsional rigidity is about 10%
...
At the end of the day it didn't impress me much.

This is very cool stuff-super impressed!! Please note, I haven't watched watched the video yet, so please ignore if you covered the questions below. Just curious on your thoughts.

To me, 10% stiffness gain is a lot. I would have killed to have gained that with minimal weight in the tube chassis cars I've designed. Why aren't you happy with that number?

Out of your scope, but it'd be interesting to see if there would be a difference if the strut bar was more of a strut panel with two wide spaced vertical attachment points and a larger vertical dimension (more box that bar) to make it more like a shear panel. I feel like something that could resist twisting loads might more effective than what's effectively a pure tension/compression member.

[tperazzo]

1) Increased torsional rigidity is about 10%
...
At the end of the day it didn't impress me much.

This is very cool stuff-super impressed!! Please note, I haven't watched watched the video yet, so please ignore if you covered the questions below. Just curious on your thoughts.

To me, 10% stiffness gain is a lot. I would have killed to have gained that with minimal weight in the tube chassis cars I've designed. Why aren't you happy with that number?

Out of your scope, but it'd be interesting to see if there would be a difference if the strut bar was more of a strut panel with two wide spaced vertical attachment points and a larger vertical dimension (more box that bar) to make it more like a shear panel. I feel like something that could resist twisting loads might more effective than what's effectively a pure tension/compression member.

Thank you!
The ten percent increase is measureable and I'm happy. If I compare the 10% to seam welding, I think was 19%, I prefer seam welding with even less weight added. So overall I'm happy with that improvement but the 10% comes from the diagonal bar and not the strut bar. I measured a torsional stiffness with a two point strut bar and a three-point strut bar configuration.
The two point strut bar did nothing to improve torsional rigidity.


Your idea of a strut panel is very good. That's exactly what I learned from this test. Rather than a solid panel I think two bars with a shape of an X in the same plane as the strut towers would do the the most to improve structural chassis rigidity. It's easy for me at this point to add two more tabs to the lower corner where it attaches to the bottom of the strut tower. These bars pictured were temporary so the actual bars that I will use will be in the shape of an X. A X shape is almost the same as a solid sheer panel.
Cheers,
Tom