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.
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.