I’m an engineer by profession, and an avid tennis player at a decent level (and curious tennis equipment tester with a somewhat photographic memory) for the last 30 years, so I’ll offer a few opinions.
By and large, I would suspect from an engineering standpoint, temperature extremes are the main culprit to long-term damage of graphite composite frames over a longer span of time. Certainly, if a racquet has been structurally abused by throwing/impacts/court wear or material loss, or improper stringing (even storing a frame with a broken string can quickly lead to structural havoc, with tensions pulling unevenly across the periphery of the racquet face), its lifespan is likely to be shortened. Excessive heat (or cold) is the main culprit, breaking down the integrity of the epoxy resins that hold the graphite, fiberglass, Kevlar, Twaron, Boron, Silicon Carbide, or whichever fibers in structrual state.
When graphite composites were introduced in the mid-1970’s, and proceeded into the early 1980’s, most were fairly heavy (at least 12 ounces), and quite expensive. Manufacturers tended to err on the side of caution by making beefier layups with thicker tubes of material, and since the first replaceable bumper guards were introduced beginning around 1983-4, most manufacturers were sure that there was ample material for wear and tear. If graphite frames were too fragile, or durable, but just too heavy, they never would have caught on in the marketplace.
If a replaceable piece of cheap plastic could do the work of some graphite, frames could be made lighter (and cheaper). The quest for lighter frames seems to have been a game of compromise between lighter weight and adequate durability. In the 1980’s and 1990’s, most manufacturers were also experimenting with aerodynamic cross sections and new materials to yield stiffness gains. With the commercial success of the first widebody frames in 1987-1988, this reached a fever pitch.
Of course, these frames are all considered “classics” now…
The only structural failures I have experienced with classics have stemmed from stringing them too tightly (when new) – I played the Kneissl White Star Pro Masters and Masters 10 between 1984-1987 and typically each hollow Graphite-Fiberglass-Kevlar frame would only last three stringings before the frame structure between string holes at the top of the head would start collapsing, but then again, I was having them strung 5 pounds above the manufacturer’s maximum suggested limit, and I was getting them free from Kneissl at the time. I also experienced head warpage on Dunlop Max 200g’s, when new, from stringing them too tightly. Later, I saw that my Head Elite Pros, Elektra Pros, Prestige Classic 600 (and any other “thinbeam” Head Prestige midsize variant) were extremely sensitive to unequal string tensions between mains and crosses and were subject to the head shape deforming if the stringer didn’t take care.
There are also some “classic” graphite racquets that were notorious for having a “glass jaw:” for instance, the midplus Head Prestige Tour / Trisys 300 was prone to shattering on off-center hits made too close to the frame (or on the frame), when new. Just a wee bit under-engineered, I think.
Most “classics,” in my experience (and these days, I only play with 1980’s vintage Head, Kneissl, and Snauwaert models, and early 1990’s vintage Fischer models, but am continuously messing around with other 1980’s models, mostly of European origin) are quite robust if treated with some consideration, and still quite usable today – even very enjoyable.
Last edited by retrowagen; 04-19-2012 at 02:47 PM.