For those who might be interested:
Luckily, gr/ep structure is extremely damage tolerant, with no fatigue problems, as the fibers efficiently act as crack stoppers. This means that the structure can have sometimes significant damage, still meet limit loading (the max ever expected) and still not have crack growth in a fatigue environment. Many tests have been done to demonstrate this property. Plus, there are no corrosion or rust problems to worry about. In other words, I wouldn't worry much about incidental damage to the 4C structure.
Boeing tested this type of gr/ep structure to not just limit (the highest actual loading ever measure/seen) but also to ultimate loading, which is 1.5 times limit. Then the structure was damaged by saw cuts and hammer blows, and then retested to at least limit again with no problems. Then the damaged structure was fatigue tested to at least two lifetimes of expected use, with no resultant increase in damage due to fatigue. Then static tested again to limit load, with no problems.
The terms the US aerospace industry uses are: limit load, the max ever expected in real life, and ultimate load, which is 1.5 times the limit load, to provide a minimum factor of safety of 1.5. Beside meeting the required fatigue spectrum criteria, aircraft structure is sized for the ultimate loading, and static tested to ~1.07% or so of ultimate load to failure, to allow for later gross weight increases. Boeing tests an airframe to that criteria, expecting no basic structural failure below that value. At least one airframe is also fatigue tested to maybe 2 lifetimes to assess the fatigue analysis conducted for the fuselage, wing, landing gear, flap and slat mechanisms, elevator and rudder, etc.
BTW, some airframes have gone higher in the static testing. I remember witnessing the 757 airframe going to ~1.13% of ultimate before wing failure occurred. This was regarded as a problem because this represented excessive unwanted strength and weight. This resulted in another weight saving program for that airplane, lol. And, as an additional point of interest, the wingtip of the 757 wing was pulled up 28FT (!!!) before failure. What we see when we fly is absolutely nothing in comparison, a foot or two.
Having said the above, though, while I am not privy to the criteria Fiat/Alfa used in the design of the 4C, I am confident that it has been designed and tested to excessive strength for road and track use, including impacts and resulting damage. This material and it's use is well known, and common in very rigorous F1 and race car design and testing.
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; 01-12-2017 at 07:34 PM.