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A theoretical investigation on the vibrational characteristics and torsional dynamic response of circumferentially cracked turbo-generator shafts
- Source :
- International Journal of Solids and Structures. 43(14-15):4063-4081
- Publication Year :
- 2006
- Publisher :
- Elsevier BV, 2006.
-
Abstract
- Turbo-generator shafts are often subjected to complex dynamic torsional loadings, resulting in generation and propagation of circumferential cracks. Mode III fatigue crack growth generally results in a fracture surface consisting of peaks and valleys, resembling a factory roof. The fracture surface roughness depends on the material microstructure, the material yield strength, and the applied cyclic torque amplitude. This crack pattern can severely affect the vibration characteristics of the shafts. The accurate evaluation of the torsional dynamic response of the turbo-generator shafts entails considering the local sources of energy loss in the crack vicinity. The two most common sources of the energy loss are the local energy loss due to the plasticity at the crack tip and frictional energy loss due to interaction of mutual crack surfaces. A theoretical procedure for evaluating the values of the system loss factors corresponding to these sources of energy loss is presented. Furthermore, the local flexibility is obtained by evaluating the resistance of the cracked section of the shaft to the rotational displacement. The shaft material is assumed to be elastic perfectly plastic. The effects of the applied Mode III stress intensity factor and the crack surface pattern parameters on the energy loss due to the friction and the energy loss due to the plasticity at the crack tip are investigated. The results show that depending on the amplitude of the applied Mode III stress intensity factor, one of these energy losses may dominate the total energy loss in the circumferentially cracked shaft. The results further indicate that the torsional dynamic response of the turbo-generator shaft is significantly affected by considering these two sources of the local energy loss.
- Subjects :
- Materials science
Crack surface interaction
Plasticity
Crack growth resistance curve
Crack closure
Fracture toughness
Materials Science(all)
Modelling and Simulation
Circumferential crack
General Materials Science
Transient torsional loading
Stress intensity factor
Local energy loss
Crack tip plasticity
business.industry
Mechanical Engineering
Applied Mathematics
Crack tip opening displacement
Structural engineering
Mechanics
Paris' law
Physics::Classical Physics
Condensed Matter Physics
Vibration
Turbo-generator shafts
Torsional dynamic response
Mechanics of Materials
Modeling and Simulation
business
Subjects
Details
- ISSN :
- 00207683
- Volume :
- 43
- Issue :
- 14-15
- Database :
- OpenAIRE
- Journal :
- International Journal of Solids and Structures
- Accession number :
- edsair.doi.dedup.....7d7d597861ea9b4e47b5eea69e8ee696
- Full Text :
- https://doi.org/10.1016/j.ijsolstr.2005.05.029