Abstract: Various embodiments provide a rotating electrical machine (10) that includes an electrical supply coupled to a stator (13), a rotor (12), and a plurality of roller elements (or brushes) (15) for transferring electrical current from the stator (13) to the rotor (12). In one embodiment, each roller element (15) is compressed between the rotor (12) and the stator (13) so that outward forces resulting from expansive properties of each roller element (15) urge the roller element (15) into contact and maintain the roller element (15) in contact with the rotor (12) and the stator (13). For example, in one embodiment, each roller element (105) has a hollow, substantially cylindrical body formed of a conductive material that is elastically biased in a radially outward direction to maintain contact with the rotor (12) and the stator (13).

Abstract: A high frequency flexure-based dynamometer for measuring vibrations to use in determining cutting forces in a tool is disclosed. The dynamometer device may operate within a pre-selected high frequency range while measuring cutting forces less than about 1 N. The dynamometer may include two coupled flexures that interact to produce vibration modes at the edge of a selected bandwidth of interest. These modes may produce a frequency response function within the desired frequency band that has a magnified response and is substantially constant. The dynamometer may include a workpiece mounted to one of the two flexures and a one or more precision accelerometers mounted to the first or second flexures. Finite element analysis may be used to optimize the flexure design.