Life span of shafts

metal fatigue bro.

titanium is not very deformative. more fracture prone.
stress fractures can form and micro cracks may not really affect the driver head until a catastrophic failure occurs.

when the failure occurs, the elastic moduli drops and the head is not structurally sound to rebound with the maximum energy returnable on a collision.

if you have been to the long drives competition in the US, you will find that they check CT on the face of the driver.

So what is CT and what is COR?

Characteristic Time or CT...

Characteristic Time (CT) is a measure of impact efficiency, sometimes called the “spring-like effect” in drivers. CT has recently replaced what used to be measured as Coefficient of Restitution, or COR. CT is a measure of the responses of a driver face to an object impacting it – in short a measure of the efficiency of impact. Higher CT impact efficiency equals more efficient energy transfer from clubface to ball, and that means more potential distance.

How do you test CT....

CT driver testing conducted by the Royal and Ancient Golf Club of St. Andrews and the United States Golf Association consists of a steel weight suspended from a pendulum, which is then released from varying heights to strike the clubface. The amount of time that the weight and clubface are in contact determines a driver’s CT; the limit has been set at 239 microseconds, plus a test tolerance of 18 microseconds, for a maximum of 257 microseconds.

COR:

The USGA imposed a limit for drivers on COR at .83, which means the speed at which a ball rebounds off a clubface when shot by a cannon (the measuring device) cannot exceed that number. Any club that does is deemed non-conforming

so how is this relevant to Turbo question?

in the past, long drives contest test COR only and once they pass, they are deemed legal. today the long drives competitor swings in exist of 130 mph and in just a couple of whacks, they can change the CT of the driver and hence gain advantage (with trampoline effect created by the altering the CT of the driver head).

Krank Golf is known for its CT integrity meaning the competitor hits all the shots with the same driver while competitor using other brands are known to use one driver for each drive for fear of failing the CT test.

so there is some truth that driver head also needs run-in to gain certain advantage but for us slow swingers, we probably never altered the CT even after a decade of use.

DGman