Carbon Tub Protection. - Page 2 - Alfa Romeo Bulletin Board & Forums

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post #16 of 20 (permalink) Old 01-13-2017, 09:34 AM
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Quote:
Originally Posted by 4Canada View Post
Great thread with lots of educational posts - thank you!

EDIT: in case these are not globally accepted terms, SLS = serviceable limit state = safe working load. ULS = ultimate limit state = max load.
4Canada, I'm glad you clarified those terms, cause I had no idea what they meant.

Del, thanks for all these explanations and write-ups. I've really enjoyed reading this entire thread.
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post #17 of 20 (permalink) Old 01-13-2017, 10:44 AM
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Interesting, those terms from 4Canada. Not familiar with that usage, as we in the US would be confused (hah, maybe not that uncommon) with the contradictory term 'ultimate limit state". We wouldn't use the terms ultimate and limit in the same definition. At least we didn't at the Big B, lol.

We use an ultimate load as 1.5 times the limit load (which specifically is the extreme actual maximum load ever to be expected). The ultimate load term is meant to represent a minimum safety margin/factor of 1.5 times the actual limit load, as accepted to be the minimum safety factor for commercial aircraft, and is the fictitious maximum load used for sizing the structure, besides that sizing required by fatigue spectrum loading.

In other words, we would size the structure for at least a calculated zero margin of safety using the fictitious ultimate load which does contain the 1.5 factor on the limit or actual maximum load.

I do strongly suspect that automotive designs, and I do know for other structures, use higher bump up factors for sizing their structure than the 1.5 factor, for commercial aircraft, for additional safety (usually because that structure would most likely not see the intensive/extensive scheduled inspections that commercial aircraft routinely get by mandate). The general 1.5 factor for commercial aircraft has been accepted by the world authorities (basically the FAA) as a reasonable compromise between safety and aircraft weight/performance.

Military aircraft, that can be a different situation. The margins of safety for military aircraft can be adjusted down for the idea that the military can accept riskier levels of pilot/crew safety in order to attain better aircraft performance.

Interesting subject, considering the increased use of gr/ep materials in the cars becoming available. Haven't had a chance yet to try to see the Lambo/U of W labs. They have been written up in the local news, but don't know if any of that is open to the public. There is a small Lambo/Composite museum in the city (Interbay area) but I also don't know if there are any tours of it. Will have to look into both areas.
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89 Milano (wife's daily driver since 1989, Shankle Sport)
91 164S (my daily driver since 1994)
94 164LS (~Q) (trip Alfa since 2000)
72 Morgan 27 (water time since 1976)

previously owned since 1964:

62 Morris MiniMinor 850, 67 Austin 1275 Cooper S (Downton 3/4 race), 64 Giulia Sprint GT (1st red one made), 72 Fiat 128 Sedan, 75 Alfetta Sedan, 78 Alfetta Sedan, 78 GTV, 81 GTV6, 86 GTV6

Last edited by Del; 01-13-2017 at 11:20 AM.
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post #18 of 20 (permalink) Old 01-13-2017, 12:29 PM
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Ok folks... I know have to read everything double all over again... I'm 'in'... with I hope will be a very lightly scratched 2016 corsa rosso...

Sent from my GT-I9500 using Tapatalk
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post #19 of 20 (permalink) Old 01-13-2017, 02:12 PM
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Del, my terms come from structural and geotechnical engineering, with which I am more familiar (no pinky ring here, but I deal with them all day, so pity me!).
Thank you for the most informative posts here. Best thread on this section of the board, for sure!


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Originally Posted by sbadaro View Post
Ok folks... I know have to read everything double all over again... I'm 'in'... with I hope will be a very lightly scratched 2016 corsa rosso...
Congrats.
Fingers crossed that it is indeed not all that badly damaged.
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post #20 of 20 (permalink) Old 01-13-2017, 05:19 PM
Del
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Not being intimately familiar with structural analysis in fields other than the aerospace industry, I haven't run across the term usage and definitions you brought to light.

While I know that different fields can have other nomenclature/definitions, the usage I discussed is the standard in aerospace design and analysis here and abroad, in commercial and military aircraft and when I worked at NASA Goddard Space Flight Center decades ago on satellite analysis. As I mentioned, the term "ultimate limit" would be confusing because in aerospace work, that represents two difference loading levels, only the ultimate loading (1.5 times limit) being used for actual sizing.

Since much of the new gr/ep work is based on aerospace materials and analysis (I suspect much from Boeing, at least for Lambo), I suspect these definitions are in use there, as well, although I am darn sure they are using much higher margins of safety, just to be sure since these cars don't have to fly, at least not very far, lol, meaning that the structure can be less weight critical, to an extent anyway. But still lighter and stronger than similar steel or aluminum structure.

Pretty cool stuff anyway. We are seeing, judging by these examples of damaged 4C's, that the insurance and repair industries are going to have to become more familiar with this material both repair costs and repair techniques. The situation should get better in the future as they get more familiar with it.
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Del

Seattle

89 Milano (wife's daily driver since 1989, Shankle Sport)
91 164S (my daily driver since 1994)
94 164LS (~Q) (trip Alfa since 2000)
72 Morgan 27 (water time since 1976)

previously owned since 1964:

62 Morris MiniMinor 850, 67 Austin 1275 Cooper S (Downton 3/4 race), 64 Giulia Sprint GT (1st red one made), 72 Fiat 128 Sedan, 75 Alfetta Sedan, 78 Alfetta Sedan, 78 GTV, 81 GTV6, 86 GTV6

Last edited by Del; 01-13-2017 at 10:37 PM.
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