- Location
- Bountiful, land of rocks
Here is a little graph showing the relationship between the inside radius and the outside radius as it relates to strength (J).
Aren't we missing something there?
How much does size matter?
- Thread starter Dominic
- Start date
Aren't we missing something there?
It's simple... research Polar Moment of Inertia. This is the reason race cars can use a large diameter lightweight (yet softer) aluminum driveshaft.
Corban_White
Well-Known Member
- Location
- Payson, AZ
- Location
- Bountiful, land of rocks
A key, a legend or whatever for the graph? (or maybe I just haven't tried to analyze it enough)
Spork
Tin Foil Hat Equipped
- Location
- Saratoga Springs, UT
Corban_White
Well-Known Member
- Location
- Payson, AZ
I made it generic so it is unitless for comparison only. The units on the Ri and Ro need to be the same and the J is a different unit...but higher is stronger!
That and it's possible to have a larger internal diameter than external...
Nope, look at the diagonal "line" where everything goes to zero (black area).
Corban_White
Well-Known Member
- Location
- Payson, AZ
In looking at these formulas and graphs, We have to realize that this is in a perfect world where the only force the shaft is subjected to is perfect rotation and the surface of the tube is without any nicks, scratches, etc., there are no bounces back and forth, etc., etc., etc. In the real world where we rockcrawl, a thicker wall is needed just to protect the shaft from rocks, bounces, etc. But, in general terms and in lab experiments, as posted above (weight for weight) bigger tube is stronger than thicker wall. Of course, thicker wall combined with bigger diam. is better (weight disregarded). That said, 10 inch solid bar would be REALLY strong (but not very practical)
Maverick
old-school
- Location
- Anywhere, thanks to my geeky droid
In looking at these formulas and graphs, We have to realize that this is in a perfect world where the only force the shaft is subjected to is perfect rotation and the surface of the tube is without any nicks, scratches, etc., there are no bounces back and forth, etc., etc., etc. In the real world where we rockcrawl, a thicker wall is needed just to protect the shaft from rocks, bounces, etc. But, in general terms and in lab experiments, as posted above (weight for weight) bigger tube is stronger than thicker wall. Of course, thicker wall combined with bigger diam. is better (weight disregarded). That said, 10 inch solid bar would be REALLY strong (but not very practical)
Nicely done!!!
One of the downsides (or limiters) to big big tubes is that they are harder to balance.
Brett (was adamant about having a 4" tube on my first blazer)