Depends on whose coldworking method you use. FTI, Fatigue Technology, has presented what seem like a million papers at conferences, particularly Aging Aircraft and ASIP, that discuss their particular coldworking apparatus. Also, a few airframers in conjuction FTI have published results that describe fatigue life improvements using the FTI coldworking equipment.
Look for Len Reid. His name appears on many of these papers. Or contact him directly at FTI. (no this is not a commercial, I do not work for FTI!).
Keep in mind that there are many manufacturers of coldworking equipment, so I'd get a couple of results from a couple of different coldworking companies.