A Cohesive Zone Model for the Investigation of the Breathing Mechanism of Transversal Cracks in Rotors

Abstract

Abstract. The presence of a crack reduces the mean stiffness of the rotor system and introduces a stiffness variation during the revolution of the shaft. How the variable part of the rotor stiffness varies between a minimum (for a closed crack) and a maximum (for an open crack), depends on the so-called breathing mechanism. The breathing mechanism is known when the open and closed parts of the cracked area are known for all angular positions of the rotor. Here, finite element (FE) and multi-body simulation (MBS) is introduced. It is based on a representation of the fracture process zone by a cohesive zone model (CZM). First, the cracked elastic shaft with various relative crack depths is modelled by FE. As a second step, the FE model of the shaft is transferred into an MBS model in order to