Chassis Materials ....

[THE INTERCEPTOR]

Hi Guys,

I am new here....I plan to use Al 6061 tubes for my electric racing go-kart.......Is this choice correct?.....we are welding.....will my chassis material be able 2 withstand d forces and weight?......+we r nt using a suspension........


If d choice is fine...wat would be d suitable diameter and thickness rqd?.....
This is a project.....Hope ur posts will enlighten me..

Sorry for not Informing.I'm planning on using Aluminium 6061 T6

 

[landuse]

Welcome to the forum! There are several members here that will not be too exited to see that you are typing as if you are on your mobile phone. Decent english (if that is your home language), or whatever (if english is not) goes a long way.

Alluminium is definately not the preferred choice for frame material. Steel tubing (square or round) will be a better choice. Have a look at these threads

http://www.diygokarts.com/vb/showthread.php?t=22277
http://www.diygokarts.com/vb/showthread.php?t=18997

 

[itsid]

If you choose the correct diameter and thickness you should be good
The material strength of steel is 6 to 8 times bigger than the one of Aluminium 6061;
(depending on what exact steel we're talking about )
you must compensate for that by increasing both, the diameter and wall thickness accordingly.
I am unable to calculate that correctly I'm afraid;
but it can be done of course.

The bigger issue I see is, it's pretty hard to weld Aluminium to make the joints as strong as you need them to be.

In short: stick with steel, or find someone who can weld aluminium and is very well capable of calculating your numbers.

'sid

 

[loud1]

even Chrome-molly steel would be easy compared to aluminum.
You need to figure out how much strength you really need to determine the actual tubing thickness you need, then you should back-gas the weld to ensure there is no O2 contamination.
Treat it as you would an aircraft frame and you should have no problems.

 

[Doc Sprocket]

Treat it as you would an aircraft frame and you should have no problems.

You'll forgive me for pointing this out, but-

Who amongst us knows how to build an airframe? I find the above statement akin to "just use the usual nuclear physics protocol...". In the direct context of a room full of gearheads and young go kart nuts, this is a complete and total head-scratcher. I think it's a reasonably safe assumption that if the OP even has to ask whether his material is suitable, he is in no way familiar with the do's and don'ts of aircraft construction. It's a go kart... Just sayin'.

 

[loud1]

LOL!

I don't know anything about building an airframe either.

 

[landuse]

LOL!

I don't know anything about building an airframe either.

 

[THE INTERCEPTOR]

Welcome to the forum! There are several members here that will not be too exited to see that you are typing as if you are on your mobile phone. Decent english (if that is your home language), or whatever (if english is not) goes a long way.

Alluminium is definately not the preferred choice for frame material. Steel tubing (square or round) will be a better choice. Have a look at these threads

http://www.diygokarts.com/vb/showthread.php?t=22277
http://www.diygokarts.com/vb/showthread.php?t=18997

Thanks for correcting my text-input.I'll improve accordingly.Is Al a really bad choice?.My kart should be 175kg (with driver).Since it's electric can't my Al support the weight.Thanks for helping.

 

[THE INTERCEPTOR]

If you choose the correct diameter and thickness you should be good
The material strength of steel is 6 to 8 times bigger than the one of Aluminium 6061;
(depending on what exact steel we're talking about )
you must compensate for that by increasing both, the diameter and wall thickness accordingly.
I am unable to calculate that correctly I'm afraid;
but it can be done of course.

The bigger issue I see is, it's pretty hard to weld Aluminium to make the joints as strong as you need them to be.

In short: stick with steel, or find someone who can weld aluminium and is very well capable of calculating your numbers.

'sid

Thanks for Replying.We will be using a Professional Welder as Al requires skill and we have none..But,We'll be calculating the Numbers.How much more should it be?.How do I calculate it?Have karts been made from Al 6061?Please give me a reference.Thanks

 

[landuse]

Thanks for Replying.We will be using a Professional Welder as Al requires skill and we have none..But,We'll be calculating the Numbers.How much more should it be?.How do I calculate it?Have karts been made from Al 6061?Please give me a reference.Thanks

If you are using a welder who knows what he is doing (very important) then you should be OK.

I don't think I know of anyone on the forum who has attempted an aluminium kart. It is just to much hassle. What if you just want to weld something to the frame at a later stage? Not so easy if you aren't geared up for it.

Is there any reason you want a Al kart? Steel is just as good, and not as hard to work with

 

[Jim-L-L]

Actually thinking like an aircraft manufacture is not a bad idea, except nothing is welded on a Aircraft fuselage

BUT if you were to fold up a monocoque out of sheet and then rivet it all together (like a fuselage) you might be in business

I believe Formula cars were built this way before carbon fibre ?

 

[loud1]

Actually thinking like an aircraft manufacture is not a bad idea, except nothing is welded on a Aircraft fuselage

True, welds are unreliable on larger aircraft, rivets are actually stronger.

I was thinking more like an ultralight airframe, see how some of those things are built and try to incorporate some of those elements into your design.

 

[landuse]

True, welds are unreliable on larger aircraft, rivets are actually stronger.

I was thinking more like an ultralight airframe, see how some of those things are built and try to incorporate some of those elements into your design.

You guys are forgetting that there are a load of parts that have to be bolted to this frame. Too light and it won't be strong enough IMO

 

[OzFab]

As was stated early in the thread, the Al idea has been tossed around but never followed through, either due to the outrgeous cost or the hassle of trying to weld it.

The bottom line is, by choosing Al, you need thicker material than steel to match the strength which adds to the cost & weight, then you have to bolt heavy steel parts to it

 

[Jim-L-L]

I'd seen this on the Edge Products website a while back, thought I might paste here !

"Can I make my chassis out of Aluminium?

by Baboon » Sat Apr 26, 2008 2:33 am

All Edge chassis & parts are made out of Mild Steel for ease of manufacture & to keep the costs reasonably cheap.

Yes it’s possible to make a buggy chassis from Aluminium.

But Aluminium has characteristics that make it much more difficult to work with compared to mild Steel.

Welding a heat treated alloy anneals the heat affected area.
So the strength of the welded area becomes the same as that material in annealed condition.
This means the welded area becomes softer than the rest of the bar work.

Unless you heat treat the whole chassis it’s going to be very weak.

Without heat treating the chassis welds & the surrounding area will be soft & prone to failure.
To beef up the structure to combat this lack of strength will add weight.

There are very few Aluminium alloys that are suitable for the welding task.
The high tensile 7000 series alloys are not suited to welding.
This is the reason that many of the early aluminium tubbed race cars were riveted.
By riveting sheet aluminium you can then use the tensile grades of this alloy.
Only the 6000 series Aluminiums are weldable, 6061 being the most suitable.
Ultimate tensile strength around 45ksi, but falls off to 24ksi when welded, heat treating will bring it back up to 45ksi.

As a guide aluminium would have to be 1.44 the thickness of steel to achieve the same bending stiffness.
But the aluminium would only be .48 of the weight even though its thicker.
So there is a good weight advantage.

When welding aluminium allot of effort has to be put into creating a stiffer joint.
Gusseting corners, extra bracing to create more stiffness.
Aluminium does not tolerate flexing at weld joints, it cracks.
This is because Aluminium fatigues very quickly.
You can flex steel all day long & it will withstand this stress.
Aluminium will fatigue & fail with only 1/3rd the amount of cycles compared to steel.
So there needs to be extra wall thickness in the tube as well as care not to have undercuts at the weld.

Corrosion is another factor.
When an object is pushed close to its mechanical limit it only takes the slightest amount of corrosion to bring it to the point of failure.

Aluminium needs to be protected from the elements as it corrodes quickly.

When all said & done you need to be skilled in the art of Aluminium fabrication.
You need to understand its advantages & disadvantages to be successful in achieving a good strong structure. "

 

[landuse]

/\/\/\

I guess that says it all!