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- Type of Document: Ph.D. Dissertation
- Language: Farsi
- Document No: 42418 (08)
- University: Sharif University of Technology
- Department: Mechanical Engineering
- Advisor(s): Behzad, Mehdi
- Abstract:
- Diagnostic and prognostic of spall defect in the rolling element bearings is investigated in this thesis. A new numerical model is proposed which considers defect size, defect clearance and defect roughness. The results of this model based on surface roughness show superior similarity to experimental data than classic model. To improve diagnostic ability in the rolling element bearings, four new methods are proposed in this thesis. These methods are short-time statistical features, local curve roughness, level crossing and wavelet packet decomposition. These methods are applied in outer ring, inner ring and ball defects and it is showed that these methods have better detection ability comparing to classic methods such as envelope analysis. The experimental data was collected by a test rig designed for this purpose. The numerical model enables investigation of defect growth by increasing defect size and clearance. Effect of defect size on vibration parameters such as acceleration rms, peak, crest factor, kurtosis and peak clarity ratio are investigated. It is shown the defect size has a linear relation with square of acceleration rms amplitude. This enables defect size estimation by vibration measurement. Rolling element prognosis is implied by using paris law model and using recursive adaptive algorithm. This method is compared to experimental data and good prediction is obtained
- Keywords:
- Rolling Bearing ; Fault Diagnosis ; Life Time Estmation ; Vibration ; Spalling ; Defect Growth
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