Effect of Two Cracks in a Rotor on Stiffness Using the Theory of Fracture Mechanics

  • Salam Ahmed AbedEmail author
  • Mohammad Reza Bahrami
  • Jassim Farij Thijel
Conference paper
Part of the Lecture Notes in Mechanical Engineering book series (LNME)


In this paper, a Jeffcott model with an offset disk rotor system with two cracks has been analyzed. By using the theory of fracture mechanics for two cracks in a Jeffcott model, a mathematical model of the rotor shafts with cracks with changing the crack depths has been created. The increase in the growth of the cracks is one of the most dangerous phenomena in rotors. The effect of changing speeds on the dynamic parameters of journal bearings (stiffness and damping) and then on Sommerfeld number has been studied. The relation of the types of stiffnesses ratios of a cracked rotor and stress concentration factor of the crack tip, with the angle of rotation rotor, has been found. The results have been obtained analytically using MATLAB. The results show that when cracks are fully open, the stiffness ratio in all directions reaches to a minimum while the concentration stress reaches to the maximum.


Rotor dynamics Stiffness ratio Cracked rotor Two cracks Stress Concentration factor 


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Copyright information

© Springer Nature Switzerland AG 2020

Authors and Affiliations

  • Salam Ahmed Abed
    • 1
    Email author
  • Mohammad Reza Bahrami
    • 2
  • Jassim Farij Thijel
    • 3
  1. 1.Peter the Great St. Petersburg Polytechnic UniversitySt. PetersburgRussia
  2. 2.Innopolis UniversityInnopolisRussia
  3. 3.Midland Refineries Company (Al—Daura Refinery), Ministry of OilBaghdadIraq

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