bigpower

into the new C6? or will it always remain to be manufactured from steel?

shopdog

Always is a long time, but I hope they don't go to an aluminum frame across the board. The reason is fatigue. With steel, as long as stresses remain below a certain limit, there will be no fatigue cracking. With aluminum, there is no fatigue limit. In other words, fatigue accumulates due to any stresses at all and the frame will eventually crack. So for a daily driver, aluminum would be a bad material choice for an auto frame.

burtonbl103

Nope


Cost is too high for the base c6

and there would be no more targa or vert

User 020720

That would be okay with me. I wish they'd bring back the FRC without forcing you to fork over the $$$ for a Z06.

BADC64GO

I don't think so, its called $$$

TCW

No. Think GM. Think sales. Think price. Think sales again.

Tom

Radical05

What ever works best

cadguymark

I could not agree more, aluminum is a horrible material for a car frame assuming you are interested in longevity, look at bicycles, it was all the rage for a few years, note too, bike makers dropped their lifetime warrantees they used to offer with steel frames

makes sense if you are looking for ultimate performance though, the guy who is looking for that will move on to another car after a short time because it will loose it's performance advantage in a couple years anyways, to him longevity means lasting a race or race season, they will gladly give up longevity if it gives them a performance advantage

kyoung

If steel is good enough for a C6.R it’s good enough for me.

Runge_Kutta

Essentially you are saying that because aluminum has an endurance
limit that it is inappropriate for use in an automotive frame. That's
a terrible extrapolation. Yes, aluminum alloys have an endurance limit
but what is important is the actual loading history and the number of cycles.
AA5754 can handle a tensile load of 135MPa for 10,000,000 cycles without
failure. An aluminum structure can be designed to handle big loads for
more cycles than you and I will be around to observe. As long as the
usage of the structure is what the designer anticipated, there's no
problem. A lot of work has been done to characterize the fatigue properties
of two key aluminum alloys used in the C6 aluminum frame:

http://www.ingentaconnect.com/conten...00011/art00014
http://cat.inist.fr/?aModele=afficheN&cpsidt=17554448

Alan Luo also has a patent on hydroforming aluminum

http://www.freepatentsonline.com/6732434.pdf

If the current frame needs a tad of help, it can use internal stiffeners

http://www.freepatentsonline.com/20050279049.pdf

You might want to read some of these papers:

2005-01-0465 : 2006 Corvette Z06 Aluminum Frame
2005-01-0466 : 2006 Corvette Z06 Aluminum Frame Engineering and Design Technologies
2005-01-0470 : 2006 Corvette Z06 Aluminum Frame Manufacturing Technologies

Between the engineers at Dana and General Motors, if they are
willing to sell me an aluminum frame C6 (non-Z06), then I'd
feel absolutely no discomfort in buying the car and beating the
crap out of it. I strongly believe these folks did a lot of homework
here.

Whether the aluminum frame goes across the board or not is a
cost and marketing issue but not an engineereing issue.

I posted this 2 years ago:
======================================== ===============
By the way, the contract to Dana for the first year is 7000 frames. Also,
the side rails are not AA5754 but AA6063-T5 (4 mm). AA6063-T5 has a higher
yield strength but LOWER fatigue strength (at 10^7 cycles). My read on this is
that the vast majority of cycles are well below the fatigue strength of AA6063-T5
and a 5-10% loss in fatigue strength was worth the increased yield strength.
This increased yield strength probably helped the weight loss (AA6xxx alloys
help weight loss more than AA5xxx alloys):

http://msl1.mit.edu/msl/meeting_0419...onstantine.pdf (page 12)

http://www.autoaluminum.org/downloads/corpub.pdf (See tables 2 and 6 in Appendix
______A. Fatigue strength correlates with ultimate tensile strength in these alloys)

It looks like the choice of materials also had to do with managing crash energy.


Ultimately, there are thresholds for both deflections and first mode frequencies.
Meeting these values may require putting back 10kg of aluminum alloy mass but I
doubt it. By the way, again, the aluminum frame used a good bit of tooling
that is used for the steel frame. Extrusions (21) were made from AA6063-T5,T6 and
AA6061-T6 (54% by mass) while sheet metal panels/stampings (63) used AA5754-O
(36% by mass) and castings (8) used A356-T6 (10% by mass). My read on this 10kg
issue is that in designing the steel C6 frame, some compromises were made to allow
a more optimal aluminum frame design (optimal designs for each frame material
would result in very different frame details). I think the steel C6 frame
is a bit overdesigned for not just the coupe but the convertible also. Besides,
GM can ill afford to be in the business of boutique aluminum frames. Hib Halverson
and a banned member (WhiteIce, BlackIce, CFour, C4FantaC, etc.) said, a year ago,
that the aluminum frame goes across the C6 line in MY2007. The GM engineer I spoke
with about the frame apologized for having to be so vague about the frame details.
A few other tidbits. The final Z06 frame including the magnesium roof structure
is 97% as stiff (frequencies not force per unit displacement or moment per unit
angular rotation) as the steel C6 frame. It appears that the fixed magnesium roof
structure increased the first mode frequencies by about 4%. As an interesting aside,
if the frame weighs 285 pounds and 54% of the mass is extrusions and most of
the mass in extrusions is included in the two side frame rails, then the two side
rails weigh about 154 pounds. Therefore, each likely weighs about 75 pounds or so.
======================================== ===============

As I recall, the side rails were made of 6000 series aluminum alloys
because of bend radii issues in manufacturing.

LTC Z06

As Runge has pointed out in other threads GM is working on ways to internally stiffening the frame so we can have an AL frame and targa. Carvaggio working with GM engineers only had to ad 80 lbs of bracing to the Z06 to make it a targa. Also GM has expressed that it wants AL frames in its trucks so to get cost down I expect we will see AL frames in all vettes at least when the C7 comes out.

superdoppler

No more targa or vert? My Prowler has an aluminum frame and is a convertible. I guess I don't understand what you mean.

UTVOL06

we will see it in the C7 I'm sure..unless GM stumbles upon a newer lighter weight frame that costs the same or less. The ultimate auto frame would be titanium. I saw a rally/offroad racing truck made out of all titanium super light weight frame. It would fly. That would cost way too much though.

I'd like to see the weight and materials of the Z06 used on the base C6. Why can't they both be the same weight? I mean does the magnesium engine cratel really add a ton of money. More carbon fiber fenders. Why can't we have a 3150lbs base C6.?

cadguymark

6063, that's what lawn chairs are made out of

it's not a cost issue? It's an engineering issue? it's ALWAYS a cost issue!

Runge_Kutta

[I hope the SAE will look at this as a sales promotion ...
Here's the abstract to SAE 2005-01-0465]

2006 Chevrolet Corvette Z06 Aluminum Spaceframe

ABSTRACT

This paper describes the engineering, manufacturing
and integration necessary to produce the Corvette’s first
ever all-aluminum spaceframe (see Figure 1). The
engineering and manufacturing of the spaceframe was a
joint venture between General Motors and suppliers
ALCOA (Aluminum Company of America) and Dana
Corporation. ALCOA led the initial design of the
spaceframe; Dana Corp led the manufacturing; General
Motors’ Engineering and Manufacturing groups led the
integration of the assembly. The aluminum spaceframe
design is modeled after the baseline steel structure of
the Corvette coupe. The aluminum spaceframe reduces
140 lbs from the steel baseline and enters the plant at
285 lbs. This frame allows the 2006 Corvette Z06 to
enter the market at a 3100 lbs curb weight. Aluminum
casting, extruding, stamping, hydroforming, laser
welding, Metal Inert Gas (MIG) welding, Self Pierce
Riveting (SPR), and full spaceframe machining make up
the main technologies used to produce this spaceframe.
Applications of these technologies produce a
spaceframe with similar torsional and bending stiffness,
and provide improvements in energy management and
mass.

[Now, the abstract to SAE 2005-01-0466 ]

2006 Chevrolet Corvette Z06 Aluminum Spaceframe Design and Engineering Technology

ABSTRACT

The General Motors (GM) Corvette design team was
challenged with providing a C6 Z06 vehicle spaceframe
that maintained the structural performance of its C5
predecessor while reducing mass by at least 56 kg. An
additional requirement inherent to the project was that
the design must be integrated into the C6 assembly
processes with minimal disruption, i.e. seamless
integration. In response to this challenge, a
collaborative team was formed, consisting of design
engineers from General Motors, Alcoa and Dana
Corporation. The result of this collaborative effort is an
aluminum Z06 spaceframe that satisfies the high
performance expectations of the vehicle while reducing
the mass by approximately 62 kg.
The frame consists of aluminum extrusions, castings and
sheets joined by MIG welding, laser welding and selfpiercing
rivets. The extrusions are 6XXX series alloys,
the castings are permanent mold A356 while the sheet
panels are formed from the 5XXX series of alloys. Of
particular note are the hydroformed aluminum rails,
designed to match the steel rails of the base C6 vehicle.
Extensive FEA verification, combined with Alcoa’s
aluminum material processing knowledge, was utilized
during the design phase of the program to place mass
where it would best serve the structural needs of the
vehicle. Performance, mass and cost were balanced to
provide an optimized aluminum Z06 spaceframe design
that enables the seamless integration of the Z06 into the
C6 assembly processes at Corvette Assembly Plant in
Bowling Green, Kentucky.

cadguymark

$$$$$

if you are willing to pay, you can have anything you want