Abstract: A stator for use in a positive displacement motor. The stator comprises a rubber compound including fiber reinforcement. The fiber reinforcement includes a plurality of elongated fibers. The elongated fibers in the fiber reinforcement create a grain direction generally with the grain in the longitudinal direction of the stator tube and across the grain in the transverse direction. The rubber compound has a 25% tensile Modulus that is at least 10% lower across the grain than with the grain. The fiber reinforcement includes a fiber loading of greater than about 2.5 phr of elongate fibers, the elongate fibers have a Modulus of greater than about 60 GPa, and the rubber compound has a 25% tensile Modulus of greater than about 400 psi against the grain and a 50% tensile Modulus of greater than about 700 psi against the grain. In some embodiments, the rubber reinforcement also comprises a blend of fibrillated fibers and short cut fibers.

Abstract: A method for measuring load performance of a positive displacement motor (PDM) test coupon. The test coupon includes a partial length of a PDM stage and is received inside a sealable test chamber. In some embodiments, the test coupon may be cut from a failed PDM stage. The test chamber is filled with test fluid. In some embodiments, the test fluid may be drilling fluid sampled from a live well. Rotation of the rotor on the test coupon actuates rotation of the stator. A braking torque is applied to the stator rotation, enabling evaluation of, for example, fatigue load performance of test coupon. Additional embodiments comprise the rotor axis and the stator axis being offset in order to simulate rotor/stator eccentricity in a full size PDM stage.