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Opis: A crack in the tooth root is the least desirable damage caused to gear units and it often causes failure of gear unit operation. For fault analyses presented in this article, gear units with real damages or faults produced on the basis of numerical simulations of real operating conditions are used; tests were carried out in a laboratory test plant. Damages in gear units can be identified by monitoring vibrations. The influences of a crack in a single-stage gear unit on produced vibrations are presented. Significant changes in tooth stiffness are caused by a fatigue crack in the tooth root whereas, in relation to other faults, changes of other dynamic parameters are more expressed. Non-stationary signals are analysed, using the family of Time Frequency Analysis tools, which include Wavelets and Joint Time Frequency Analyses.
Ključne besede: gear unit, vibrations, tooth root, time frequency analysis tool
Objavljeno v DKUM: 30.06.2017; Ogledov: 1267; Prenosov: 400
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Opis: A computational model for determination of the service life of gears with regard to bending fatigue at gear tooth root is presented. In conventional fatigue models of the gear tooth root, it is usual to approximate actual gear load with a pulsating force acting at the highest point of the single tooth contact. However, in actual gear operation, the magnitude as well as the position of the force changes as the gear rotates. A study to determine the effect of moving gear tooth load on the gear service life is performed. The fatigue process leading to tooth breakage is divided into crack-initiation and crack-propagation period. The critical plane damage model has been used to determine the number of stress cycles required for the fatigue crack initiation. The finite-element method and linear elastic fracture mechanics theories are then used for the further simulation of the fatigue crack growth.
Ključne besede: crack closure, crack initiation, crack propagation, gear tooth root, moving load
Objavljeno v DKUM: 31.05.2012; Ogledov: 1707; Prenosov: 93
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