McDave wrote:Aluminium trailers are much lighter and stronger overall. Also more expensive, but you get what you pay for... hopefully. If I had it to do over, I would be willing to delay my build in order to afford an all aluminium trailer. Hindsight being what it is and all...
McDave
I've always wondered about the weight and strength comparison of aluminum to steel so I looked this up(from
https://sciencing.com/strength-tubing-v ... 11536.html):
The strength of any material can be described by a physical parameter known as Young’s modulus of elasticity, measured in force per unit area. This parameter can be used to assess the strength of aluminum and steel tubing.
Young’s Modulus
At 70 degrees Fahrenheit, Young’s modulus of elasticity for aluminum is 10 million pounds per square inch (psi). Young’s modulus of elasticity for steel, regardless of its type, is around 30 million psi. This effectively means that steel tubing is three times stronger than aluminum tubing of the same dimensions.
Weight
Size for size, steel is around three times heavier than aluminum. However, because the walls of aluminum tubing need to be three times thicker than steel tubing to achieve the bending strength, any weight advantage is lost.So let's play around with a deflection calculator for square tubing at
http://metalgeek.com/static/deflection.php 2" STEEL tubing, 0.120" wall, 96" long with 500 lbs load in the center, ends detachedtype = steel ends = free
est. weight = 3.068# per footOD = 2" ID = 1.76"
Moment of Inertia = 0.5332
Deflection = 0.582"Then we attempt to find a similar sized aluminum beam that would have the a similar deflection by varying wall thickness. Going from .120 steel to .5 aluminum gets this:
2" ALUMINUM tubing, 0.5" wall, 96" long with 500 lbs load in the center, ends detached type = aluminum ends = free
est. weight = 3.4917# per footOD = 2" ID = 1"
Moment of Inertia = 1.25
Deflection = 0.7373Note how with same size tubing the wall size has to quadruple to approach a similar deflection(but not reach the deflection of steel) and the aluminum actually weighs more.
Let's up the size of the aluminum tubing but keep .120 wall:
3" ALUMINUM tubing, 0.120" wall, 96" long with 500 lbs load in the center, ends detachedtype = aluminum ends = free
est. weight = 1.609# per footOD = 3." ID = 2.76"
Moment of Inertia = 1.9143
Deflection = 0.4814"This gives us less deflection than the original steel beam and a little over half the weight.
So for a given profile, in this example 2" square, it looks like steel gives a better weight to strength ratio. But if you are willing to change the profile, aluminum beats steel in weight to strength.