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何正嘉, Jiawei Xiang∗, Xuefeng Chen, Yumin He, Zhengjia He
Finite Elements in Analysis and Design 42(2006)1269-1280,-0001,():
-1年11月30日
Based on two-dimensional tensor product B-spline wavelet on the interval (BSWI), a class of C0 type plate elements is constructed to solve plane elastomechanics and moderately thick plate problems. Instead of traditional polynomial interpolation, the scaling functions of two-dimensional tensor product BSWI are employed to form the shape functions and construct BSWI elements. Unlike the process of direct wavelets adding in the previous work, the elemental displacement field represented by the coefficients of wavelets expansions is transformed into edges and internal modes via the constructed transformation matrix in this paper. The method combines the versatility of the conventional finite element method (FEM) with the accuracy of B-spline functions approximation and various basis functions for structural analysis. Some numerical examples are studied to demonstrate the proposed method and the numerical results presented are in good agreement with the closed-form or traditional FEM solutions
B-spline wavelet on the interval, Tensor product wavelet, Transformation matrix, Plane elastomechanics element, Mindlin plate element
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【期刊论文】TECHNICAL NOTE Experiments on Crack Identification in Cantilever Beams
何正嘉, by X.F. Chen, Z.J. He and J.W. Xiang
Vol. 45, No.3, June 2005,-0001,():
-1年11月30日
In this paper we present an experimental investigation of the identification of crack location and size. By providing the first three natural frequencies through vibration measurements, curves of crack equivalent stiffness versus crack location are plotted, and the intersection of the three curves predicts the crack location and size. In the experiments, the cracked specimens were made using a wire-cut electrical discharge machine, and the cantilever beams were excited next to the free end by means of an impulse force hammer. In order to obtain the accurate natural frequencies from the transient signal measured, the method of zoom fast Fourier transform is adopted to improve frequency resolution. From experimental results, it is observed that the identification errors of crack location and size are less than 2% and 4%, respectively. The effectiveness of crack identification through vibration measurements is verified.
Crack identification, natural frequency, cantilever beams
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何正嘉, Peng Chena, *, Masatoshi Taniguchib, Toshio Toyotab, Zhengja Hec
Mechanical Systems and Signal Processing 19(2005)175-194,-0001,():
-1年11月30日
This paper proposes a fault diagnosis method for plant machinery in an unsteady operating condition using instantaneous power spectrum (IPS) and genetic programming (GP). IPS is used to extract feature frequencies of each machine state from measured vibration signals for distinguishing faults by relative crossing information. Excellent symptom parameters for detecting faults are automatically generated by the GP. The excellent symptom parameters generated by GP can sensitively reflect the characteristics of signals for precise diagnosis. The method proposed in this paper is verified by applying it to the fault diagnosis of a rolling bearing.
Machinery fault diagnosis, Unsteady operating condition, Genetic programming, Instantaneous power spectrum, Relative crossing information, Rolling bearing
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