Abstract: Rotor and/or stator designs and methods thereof to improve progressive cavity motor or pump durability. In one or more implementations, the rotor may have a variable outer diameter or variable stiffness along an axial length thereof. The stator may similarly have a variable inner diameter or variable stiffness, which may compliment or diverge from the variable outer diameter or variable stiffness of the rotor.

Abstract: A method for determining a remaining life span of an elastomer in a motor. The method includes running a downhole tool into a wellbore. The downhole tool includes a mud motor having a rotor and a stator. At least one of the rotor or the stator includes, or is at least partially made from, an elastomer. A number of cycles before the elastomer fails may be predicted. A number of cycles during a time period may be determined. A change in a remaining life span of the elastomer over the time period may be determined, based upon the number of cycles before the elastomer fails and the number of cycles during the time period.