PERFORMANCE EVALUATION OF SOME VIBRATION PROTECTION PATTERNS APPLICABLE TO ITEMS OF MACHINERY INDUCING HARMONIC AND IMPULSIVE LOADS

• Main Author: Osipova Maria Vladimirovna
• Format: Article
• Language: English
• Published: Moscow State University of Civil Engineering (MGSU) 2012-12-01
• Series: Vestnik MGSU
• Subjects: additional inertial block; vibration protection; method of normalized eigenforms; impulse response function; transfer function; tuned mass damper
• Online Access: http://vestnikmgsu.ru/files/archive/issues/2012/11/ru/11.pdf

Efficiency of several vibration protection patterns applicable to items of machinery inducing harmonic and impulsive loads is assessed on the basis of the foundation displacements, accelerations and the transfer ratio. Identification of accelerations is important due to potential negative influence of vibration on adjacent structures. Vibration protection patterns analyzed in the article represent a SDOF system, a scheme that has an additional inertial block and a system with a Passive Tuned Mass Damper (PTMD). The author considers vertical oscillations of systems that have one and two degrees of freedom by taking account of transient modes of operation of items of machinery inducing harmonic loads (modes of activation and stopping). The two methods are employed, including the method of normalized eigenforms and the method of transfer and impulse response functions. The method of normalized eigenforms relies on transforming the mass displacement vector into a linear combination of eigenforms. Solutions are obtained by applying the Duhamel integral. The method of transfer and impulse response functions is based on a correlation between these functions. This method proves to be efficient in respect of less than 3 DOF systems, and it doesn't require any identification of eigenforms. The PTMD system has proved to be particularly efficient if applied to the items of machinery inducing harmonic loads (the fan), as the damper is tuned to the operational frequency of the machines. The system that has an additional inertial block is mostly efficient if applied to items of machinery inducing impulsive loads (the sledge hammer) due to smaller dynamic loads transmitted to the foundation.