Terry J Dunlap

US Patent:

42839572, Aug 18, 1981

Filed:

Jun 25, 1979

Appl. No.:

6/051947

Inventors:

Gerald S. Zobrist - Cincinnati OH
Terry A. Dunlap - Cincinnati OH
Richard H. Russell - Milford OH

Assignee:

Zonic Corporation - Cincinnati OH

International Classification:

G01N 336

US Classification:

73814

Abstract:

An exciter is disclosed for applying a dynamic torsional force to a rotating structure, such as to the shaft of a turbine generator, the axle of a vehicle, or the like, during mechanical testing to determine the mechanical response characteristics, natural modes of vibration, fatigue life, etc. , of the structure. The exciter includes a rotary hydraulic actuator having a housing secured to the structure to be tested and a driveshaft which is rotatable relative to the housing as well as an inertial mass mounted on the driveshaft. The exciter also includes a hydraulic power supply for the actuator and an electrohydraulic means comprising a torque setpoint circuit for producing a torque command signal to set the desired amplitude and frequency of oscillation of the inertial mass, a position setpoint circuit for producing a position command signal to set the midpoint of the arc through which the inertial mass oscillates, means for producing a torque feedback signal dependent on the actual dynamic torsional force produced by the oscillating inertial mass, means for producing a position feedback signal dependent on the average angular position of the inertial mass relative to the structure as the inertial mass oscillates and a controller responsive to the command and feedback signals for energizing a servovalve that controls the supply of pressurized fluid to the actuator. The actuator oscillates the inertial mass relative to the structure to be tested in order to produce a controlled dynamic torsional force on the rotating structure.