58 results about "Modal damping ratio" patented technology

The invention discloses a steam turbine blade vibration test method and device. The method steps are that firstly, a blade force vibration status is analyzed and a blade excitation force mathematical model is built. Secondly, an excitation force is imposed on the blade by a vibration source. The frequency of the excitation force is regulated until resonance is generated between the blade and the vibration source. Vibration characteristics parameters values of the blade under the excitation force are measured. Thirdly, blade damping characteristics parameters, including modal damping ratio, damper contact stiffness and blade dynamic stress, are worked out according to the vibration characteristics parameters values. The device includes a test bed, a blade clamping mechanism arranged on thetest bed, an excitation generator, a vibration parameter detector and a data processing system. The excitation vibration generator is fixed on the test bed. The excitation vibration head of the excitation vibration generator is fixed with the blade. Corresponding to the blade, the vibration parameter detector transforms the vibration signals of the blade into electric signals, which are input into the data processing system. The invention proves the vibration mechanism of the damping blade. A calculation model of the damping blade is constructed through the test parameters. Experience design is terminated. The blade design is standardized to step into a scientific design orbit.

A golf club head includes a striking face, a crown and a sole. The crown and / or the sole includes an FRP member formed by a fiber reinforced plastic that contains a fiber and a matrix resin. The head has one or more characteristic mode shapes each having a natural frequency of 3000 Hz or greater and 5000 Hz or less. Of the one or more characteristic mode shapes, one characteristic mode shape that has a largest amplitude of a center of figure of the FRP member is defined as a specific characteristic mode shape, the specific characteristic mode shape has a frequency that is defined as a specific modal frequency, and the specific modal frequency has a modal damping ratio that is defined as a specific modal damping ratio. The specific modal damping ratio of the head is less than or equal to 0.6%.

A servo controller includes: a sinusoidal wave disturbance input unit for supplying a sinusoidal wave disturbance to a speed control loop including a speed command generator, a torque command generator and a speed detector; a frequency response calculator for estimating the gain and phase from the output of the speed control loop; a resonance frequency detector for detecting resonance frequencies at which the gain becomes maximum; a resonance mode characteristics analyzer for estimating resonance characteristics from the frequency response; and, a reference modal damping ratio retainer for retaining a reference modal damping ratio as a resonance characteristic corresponding to the reference lubricating condition, and the resonance mode characteristics analyzer calculates lubrication characteristics on the basis of the reference modal damping ratio and the measured modal damping ratio at the resonance frequency corresponding to the reference modal damping ratio.