Experimental tests were conducted to further demonstrate the ability of the influence coefficient method to achieve precise balance of flexible rotors of virtually any design for operation through virtually any speed range. Four distinct practical aspects of flexible-rotor balancing were inves¬tigated in the present work:n1. Balancing for operation through multiple bending critical speedsn2. Balancing of rotors mounted in both rigid and flexible bearing supports, the latter having significantly different stiffnesses in the horizontal and vertical directions so as to cause severe ellipticity in the vibration orbitsn3. Balancing of rotors with various amounts of measured vibration response information (e.g., numbers of vibration data sets and numbers and types of vibration sensors) and with different numbers of correction planesn4. Balancing of rotors with different (though arbitrary) initial unbalance configurations Tests were made on a laboratory quality machine having a 122 cm (48 in.) long rotor weighing 50 kg (110 lb) and covering a speed range up to 18 000 rpm. The balancing method was in every instance effective, practical, and economical and permitted safe rotor operation over the full speed range covering four rotor bending critical speeds. Improved correction weight removal methods for rotor balancing were investigated. Material removal from a rotating disk was demonstrated through application of a commercially available laser.
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