Abstract
The dynamic absorber is the special case of a tuned absorber in which the natural frequency of oscillation is directly proportional to the rotational speed of the shaft which carries it. Four typical absorbers are studied in detail; in each case, the tuning and amplitude equations are derived and, for the roller types, expressions are obtained for the maximum roller amplitudes which may be attained without the occurrence of slipping.
As with the simple tuned absorber, the dynamic absorber may be used to prevent resonance with one torque harmonic, and will operate satisfactorily so long as it is connected to the main system at the point of application of this exciting torque. There is therefore no difficulty in fitting such an absorber to a single-row radial engine in which all the exciting torques act at one crank throw.
An engine having a multi-throw crankshaft presents more difficulty, as it is necessary to determine how many absorbers to fit, and the manner in which the stabilizing torque is distributed between these absorbers. Such a case is fully analysed, and examples are given of the application of dynamic absorbers to a typical multi-throw aero-engine crankshaft. The method is quite general, and can be applied to any other type of engine as desired.
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