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  #161  
Old 28-11-2011
Fabs Fabs is online now
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Finished me bag of pop corns, gonna get another one.

Funniest bit I read on this thread must be that different grades of aluminium will handle different
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  #162  
Old 28-11-2011
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Originally Posted by Fabs View Post
Finished me bag of pop corns, gonna get another one.

Funniest bit I read on this thread must be that different grades of aluminium will handle different
And of course the funny thing is it could be true due to compounds and stresses on different ally grades.....
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  #163  
Old 28-11-2011
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And of course the funny thing is it could be true due to compounds and stresses on different ally grades.....
And of course anyone who thinks this has never studied materials.
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  #164  
Old 28-11-2011
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Fabs, what colour/flavour Ally handles best?
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  #165  
Old 28-11-2011
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And of course anyone who thinks this has never studied materials.
Fool!!!
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  #166  
Old 28-11-2011
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Quote:
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Fabs, what colour/flavour Ally handles best?
PINK cuz it handles SWEEEEET
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  #167  
Old 28-11-2011
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Fool!!!
Maybe, but one that knows the difference between strength and stiffness
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  #168  
Old 28-11-2011
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Originally Posted by Fabs View Post
Maybe, but one that knows the difference between strength and stiffness
Going a bit off topic here , can you enlighten us fabs,I do work with metal although not ally very much, and I haven't done studies on it. But I know if I had a bit of say 1000 series ally it would be a dam sight easier to bend than a c4.1, Durango or losi chassis im guessing these must be around the 5-6000 series or are you talking about the way it is treated?
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  #169  
Old 28-11-2011
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Quote:
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Going a bit off topic here , can you enlighten us fabs,I do work with metal although not ally very much, and I haven't done studies on it. But I know if I had a bit of say 1000 series ally it would be a dam sight easier to bend than a c4.1, Durango or losi chassis im guessing these must be around the 5-6000 series or are you talking about the way it is treated?
5-6000 series, was that a guess...?
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  #170  
Old 28-11-2011
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Ok.

First of all 1000, 2000 series etc does not relate to mechanical properties but to the main alloy. Example a 2024 is stronger than a 6082 given the same heat treatment.

Second the heat treatment (which the T6, T4 etc relates to) has no effect on stiffness. Only on strength.

Now read these:

http://en.wikipedia.org/wiki/Strength_of_materials

http://en.wikipedia.org/wiki/Stiffness

http://en.wikipedia.org/wiki/Young%27s_modulus

The key words here are failure, plastic deformation and elastic deformation.

Now what is important to understand is this:

There is no relation between the strength of a material and its stiffness.

The strength depends on many things : type of material (steel, aluminium, plastic etc), the composition of this material (which alloys, what direction for the carbon fibres, the quantity of fibres in the plastic), and in the case of metals, how it was made (how long it took to cool it down, what heat treatment etc). So, for aluminium the range of tensile strength varies between less than 100 MPa and over 500 MPa, the material with the highest tensile strength being 7075 T6.

The stiffness of the material depends on only one thing: what type of material it is. All steels have the same modulus of elasticity, all aluminiums have the same modulus of elasticity, this is true for all metals. This isn't true for carbon fibre and other composite materials.

Which brings us to our subject of interest: a chassis stiffness!

Given that during normal use, the chassis should deform but not in a permanent manner, we can safely assume that the material will stay in the zone of elastic deformation. And given that elastic deformation means direct relation to Young's Modulus only, then we can safely assume that all aluminium chassis will behave the same on the track no matter what grade of aluminium.

Now Andy, to answer your question:

When bending a chassis you go over the tensile yeld strength, into the zone of plastic (permanent) deformation. Given that not all aluminium have the same tensile yeld strength, it is normal and logical that the force varies depending on the material.

Now hope that clears it up and we have no more of this sillyness? If you haven't got a clue what I'm on about, just trusssssssssst me
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  #171  
Old 28-11-2011
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Fabs.

Fried my brain that did...

All i want to know, from someone impartial and in the know is..
'Will it Bend' under 'normal use', i.e landing off a big jump on a harsh outdoor track ?
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  #172  
Old 28-11-2011
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C4 chassis info pm'ed to you Chris
Hope you like!
Sorry for my delayed reply but I've been busy
Cheers
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  #173  
Old 28-11-2011
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Shall we answer andys question together fabs?
No confiring lol
Bet we both say the same lol
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  #174  
Old 28-11-2011
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Actually I think cml should answer this Andy
It's there car/thread.
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  #175  
Old 28-11-2011
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define normal use...
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  #176  
Old 28-11-2011
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Ask mardave lol
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  #177  
Old 28-11-2011
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Actualy I am impartial and I say they will bend/sag
Flame me now! Just my opinion based upon other cars I have constructed similar just to test quickly wacky transmissions out on
What does everyone else recon?
Any way what do I know?
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  #178  
Old 29-11-2011
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Wow, science returns.

You might want to point out what you do with the material does make a difference to chassis stiffness, so a thicker chassis would be stiffer..

At the moment it reads like any alloy chassis has the same stiffness.


Quote:
Originally Posted by Fabs View Post
Ok.

First of all 1000, 2000 series etc does not relate to mechanical properties but to the main alloy. Example a 2024 is stronger than a 6082 given the same heat treatment.

Second the heat treatment (which the T6, T4 etc relates to) has no effect on stiffness. Only on strength.

Now read these:

http://en.wikipedia.org/wiki/Strength_of_materials

http://en.wikipedia.org/wiki/Stiffness

http://en.wikipedia.org/wiki/Young%27s_modulus

The key words here are failure, plastic deformation and elastic deformation.

Now what is important to understand is this:

There is no relation between the strength of a material and its stiffness.

The strength depends on many things : type of material (steel, aluminium, plastic etc), the composition of this material (which alloys, what direction for the carbon fibres, the quantity of fibres in the plastic), and in the case of metals, how it was made (how long it took to cool it down, what heat treatment etc). So, for aluminium the range of tensile strength varies between less than 100 MPa and over 500 MPa, the material with the highest tensile strength being 7075 T6.

The stiffness of the material depends on only one thing: what type of material it is. All steels have the same modulus of elasticity, all aluminiums have the same modulus of elasticity, this is true for all metals. This isn't true for carbon fibre and other composite materials.

Which brings us to our subject of interest: a chassis stiffness!

Given that during normal use, the chassis should deform but not in a permanent manner, we can safely assume that the material will stay in the zone of elastic deformation. And given that elastic deformation means direct relation to Young's Modulus only, then we can safely assume that all aluminium chassis will behave the same on the track no matter what grade of aluminium.

Now Andy, to answer your question:

When bending a chassis you go over the tensile yeld strength, into the zone of plastic (permanent) deformation. Given that not all aluminium have the same tensile yeld strength, it is normal and logical that the force varies depending on the material.

Now hope that clears it up and we have no more of this sillyness? If you haven't got a clue what I'm on about, just trusssssssssst me
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  #179  
Old 30-11-2011
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Just for you son

Last edited by daz; 30-11-2011 at 10:54 AM. Reason: I love little Ben..
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  #180  
Old 01-12-2011
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Quote:
Originally Posted by Fabs View Post
Ok.

First of all 1000, 2000 series etc does not relate to mechanical properties but to the main alloy......
just trusssssssssst me

Fabs is 100 million percent correct. Technically.

HOWEVER.

There is one little twist in this story. People tend to buy expensive little cars and plow them into solid objects at high speed, I think that is a fair thing to conclude from this thread. So manufacturers are forced to design chassis to cope with that. That is where material strength does influence stiffness, through dimensions.
Example: if the C4.1 chassis were made out of 6061-T6, it would need to be 4mm thick in order to be strong enough. If it had been 7075-T6 - which is very strong - 3mm would have sufficed.
Both materials behave exactly the same in the elastic part of the deformation curve, but the strongest one allows lighter construction, and thus, more flex. A thinner chassis flexes more.

Stronger alloy = more flex. Counterintuitive, eh?


Very similar story: http://www.willswing.com/Support/FAQItem.asp?reqFAQ=66
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