Abstract: Wigner-Ville distribution (WVD) has the characteristics of very high-energy accumulation and excellent time-frequency resolution. It is a good way to extract fault feature of acoustic emission (AE) signals due to mechanical component broken. The characteristics of typical AE signals initiated by damages are analyzed. Based on the extracting principle of AE signals from damaged components, the WVD analysis method of AE signal is developed. WVD method is employed to the fault diagnosis of rolling bearings with AE technique. The fault features reading from experimental data analysis are clear, accurate and intuitionistic, meantime, the validity and accuracy of WVD method proposed are nice from the experimental results. Therefore, WVD method is useful for condition monitoring and fault diagnosis in conjunction with AE technique.

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Fatigue Propagation Lifetime Prediction of Rotary Kiln Weld Shell

Authors: Y.P. Shen, G.F. Bin, S.L. Wang

Abstract: Rotary kin shell is welded by cylindrical steel plates. Crack propagation of weld toes near supporting rollers until final fracture is the main failure form. Based on fracture mechanics, an overall intensity factor with regard to circumferential stress, concentrated stress, residual stress, and temperature stress is used to asses the crack growth. Under complex overloading conditions, the major factor, namely, circumferential stress across shell, is calculated by using finite element (FE) code ANSYS. Concentrated stress, residual stress, and temperature stress play a major role in the fatigue growth behavior, thus their effects are considered in a theoretical analysis to be included in the overall intensity factor. A certain extent good lifetime results are obtained compared with practical observation. This paper presents a reasonable procedure to evaluate propagation lifetime of weld shell, and the results are quit significant for equipment daily maintenance of rotary kiln.

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