Cycle Time Calculation

Well I think you need to define a few things first.

You're refering to the the part also know as the drive shaft, no?

How many miles or time do you consider a lifetime?

What ratio is the rear end of the test vehicle?

What is the average speed for the test?

Calculate lifetime????? Testing torque limits and endurance makes sense, but not lifecycle...unless you are designing for a tank or other such kind of long-life-cycle system...and, even then, drive shafts are replaceable. If you do not know test concepts, or how to calculate time to failure under the anticipated use conditions, you probably should not be tasked to make the calculations--other than to derive estimates from established references--for which software can be purchased and learned in short order. Since MTBF frequently enters into warranty (intended to protect the mfr/seller) this is typically not something left to a novitiate's judgment; unless of course there is time allowance for a lengthy learning curve, and supplemental education. In other words, is reliability testing and assurance to become your engineering "specialty"? Or are you just winging it?

In our company suggest 3000 hrs working hrs is considered as a life time(warrenty period) for a spider cross.In need formula to estimate warrenty hrs & also to test a shaft with torque capacity of 12000 Nm in endurance test

What is the application for the driveshaft?

Due to the characteristics of a non-constant speed transmission, a cycle could be one shaft turn, or could be the event of loading and unloading all the assembly. I would like also to know what's the application before going further.

If it's auto industry, the answer is simple.

"Ask the customer!" They will have detailed and prolonged testing expectations for every component in the vehicle.

Unless you satisfy their expectations, you'll never get past "production part approval process" (PPAP)