How much heavier would the typical passenger car be

[Don Vito Corleone]

Titanium is roughly half as heavy as steel. 6mm-thick ti would be what, maybe 50% heavier than the steel that's currently used? I'm presuming the steel that's used now is 2mm thick.

A better solution (though still prohibitively expensive) would be to use ti that is the same thickness as the steel, or at most 50% thicker. Ti is almost as strong as steel and has a superior modulus of elasticity. It would bounce back from a lot of the small impacts that dent steel.

 

[gsellis]

Probably cheaper to use carbon fiber with kevlar layers.

 

[Don Vito Corleone]

Originally posted by: gsellis
Probably cheaper to use carbon fiber with kevlar layers.

That wouldn't really solve the problem at all. CF is very strong but has very poor elasticity, and thus will break rather than bend. It would indeed be superior in strength and stiffness/weight, but not as resilient as titanium.

 

[gsellis]

Originally posted by: DonVito

Originally posted by: gsellis
Probably cheaper to use carbon fiber with kevlar layers.

That wouldn't really solve the problem at all. CF is very strong but has very poor elasticity, and thus will break rather than bend. It would indeed be superior in strength and stiffness/weight, but not as resilient as titanium.

Hence the Kelvar layers. But, it would still have that tendency to starburst. Ti would still score though, IIRC. And picking up pieces of Ti is sure less worrisome then CF (cut you - picked up many pieces of race car before.)

 

[alkemyst]

Originally posted by: DonVito
Titanium is roughly half as heavy as steel. 6mm-thick ti would be what, maybe 50% heavier than the steel that's currently used? I'm presuming the steel that's used now is 2mm thick.

A better solution (though still prohibitively expensive) would be to use ti that is the same thickness as the steel, or at most 50% thicker. Ti is almost as strong as steel and has a superior modulus of elasticity. It would bounce back from a lot of the small impacts that dent steel.

2mm?

Also you are probably talking about some kind of Ti Alloy (google?).

Ti's modulus of elasticity compares favorably with those of aluminum (10.4x10^6) and magnesium (6.4x10^6) but poorly with that of steel (29x10^6).

Like the modulus of elasticity...rigidity and shear falls between that of aluminum and that of steel.

To the other posters thinking "wow it's Ti, must be teh lighter"....go measure out 6mm, then compare that to the 'lip' on your hood, door, trunk....

 

[Don Vito Corleone]

Originally posted by: alkemyst

2mm?

Also you are probably talking about some kind of Ti Alloy (google?).

Ti's modulus of elasticity compares favorably with those of aluminum (10.4x10^6) and magnesium (6.4x10^6) but poorly with that of steel (29x10^6).

Like the modulus of elasticity...rigidity and shear falls between that of aluminum and that of steel.

To the other posters thinking "wow it's Ti, must be teh lighter"....go measure out 6mm, then compare that to the 'lip' on your hood, door, trunk....

I was just ballparking the thickness of the body steel - I really don't know. Is it closer to 1mm?

Ti has superior elongation in comparison to steel. It has elongation from 20-30 percent, compared to 10-15 percent for steel and 6-12 percent for aluminum. I misspoke when I referred to its modulus - it seems to me elongation is the most relevant characteristic when it comes to toughness and resiliency. I know my ti MTB has shown no marks from impacts that would have badly dented my steel bikes.

 

[alkemyst]

Originally posted by: DonVito
I was just ballparking the thickness of the body steel - I really don't know. Is it closer to 1mm?

Ti has superior elongation in comparison to steel. It has elongation from 20-30 percent, compared to 10-15 percent for steel and 6-12 percent for aluminum. I misspoke when I referred to its modulus - it seems to me elongation is the most relevant characteristic when it comes to toughness and resiliency. I know my ti MTB has shown no marks from impacts that would have badly dented my steel bikes.

Your facts seem to come from bicycle sites just based on a quick search. Elongation has to do with bending though...density would be the toughness, and resilency based on elasticity.

there is a good write up on the pluses and minuses for frames here:
http://www2.sjsu.edu/orgs/asmtms/artcle/titan.htm

Here is a site with the materials:
http://www.alleghenyludlum.com/ludlum/p...oducts/xq/asp/G.12/qx/ProductLine.html