A resonance torsional vibration damping system includes a member having at least one node location along its length. An energy exchanging device, such as a fly wheel and eddy current brake, is operably connected to the member at a damping location that is a distance away from the at least one node location. The energy exchanging device is capable of imparting a plurality of successive torsional impulses to the member. A suitable sensor, such as an angular amplitude sensor or a torsional stress sensor, is utilized to detect the presence of a resonance torsional vibration in the member. A computer is in communication with the energy exchanging device and the sensor, and is capable of controlling the energy exchanging device.

Active torsional vibration damper

Undesirable vibrations are controlled in a mechanical structure by confining the vibrations to one or more specified areas of the structure and then dissipating the confined energy by damping. Vibration confinement is achieved using a confinement device (26, 44, 64, 92, 1020, 1420, 1508 and 1608) which effectively applies both translational and torsional forces to the structure (20, 30, 60, 90, 1400, 1500 and 1602). The strength of the translational and torsional forces, and the position of the confinement device are chosen to select a vibrational energy confinement region (between X2 and X3), (30a, 90a, 1510 and 1610). Damping elements (30, 42, 66, 96 and 1422) concentrated in the vibration confinement region to dissipate the confined vibrational energy. Judicious selection of the confinement region permits the structure to avoid the transfer of vibrational energy to particularly sensitive portions of the structure, or to direct vibrational energy to a portion of the structure. Optimization procedures are presented for designing structures having optimized placement and selection of the vibration confinement device and damping devices.

Apparatus and method for confinement and damping of vibration energy

A method for controlling vibration energy in a structure having a vibrating member using a vibration confinement device is provided. The vibrating member has boundaries and vibrates relative to the boundaries. The method includes selecting a vibration confinement region in the vibrating member relative to the boundaries. Determining an effective torsional stiffness and an effective translational stiffness for the vibration confinement device is included in the method. The method includes determining an operating position relative to the boundaries for the vibration confinement device on the vibrating member to define a determined position. The method includes positioning the vibration confinement device at the determined position to substantially confine the vibration energy to the vibration confinement region.

Vibration control by confinement of vibration energy

An injection molding apparatus includes a melt furnace and a metal supply system located in the melt furnace. The metal supply system includes a pump. The injection molding apparatus also includes a first metal inlet from the melt furnace to the metal supply system and a vertical injection mechanism adapted to inject liquid metal into a die system. The injection molding apparatus also includes a second metal inlet from the metal supply system to the vertical injection mechanism.

Method and apparatus for manufacturing metallic parts by die casting

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.

Torsional exciter for a rotating structure

A vibration damper test machine including a rotary mass elastic system and characterized by electromagnetic means for exciting the system in the form of an oscillating torque of resonant frequency to produce large torsional vibrations at an end of the system adapted to receive a torsional vibration damper. The electromagnetic excitation means is arranged such that an excitation frequency corresponding to a predetermined order of vibration and an excitation torque corresponding to the order of vibration amplitude can be induced into the mass elastic system to simulate conditions existing in a particular engine. An observed excessive amount of strain on the system at resonance provides an indication of malfunction of the damper.

Nelson A Jones

Papers

Vibration damper test machine