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学者姓名：刘增华
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摘要 ：
利用导波的远场检测优势和机器学习模型,开展管道弯曲处腐蚀损伤程度智能辨识方法研究。在普通碳质钢管弯头处加工不同程度的腐蚀缺陷,按腐蚀程度分为10个等级。采用自激自收和一激一收两种信号激励接收方式,在管道中激励具有非频散的T(0,1)型超声导波,采集得到不同腐蚀程度缺陷对应的导波检测信号。在时域和频域对检测信号进行分析,提取多个导波信号特征值用于表征损伤程度,并通过BP神经网络和支持向量机两种分类模型对数据进行训练分析得到缺陷损伤辨识模型,实现弯曲处腐蚀程度的准确辨识。研究中分析两种模型的超参数对缺陷辨识模型精度的影响,对比研究两种模型对弯管腐蚀损伤辨识的性能。试验结果表明,两种损伤辨识模型对不...
关键词 ：
超声导波 超声导波 BP神经网络 BP神经网络 损伤特征值 损伤特征值 支持向量机 支持向量机 弯管腐蚀 弯管腐蚀
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| GB/T 7714 | 周澄 , 邓菲 , 刘尧 et al. 基于神经网络和支持向量机的导波弯管腐蚀损伤程度辨识研究 [J]. | 机械工程学报 , 2021 , 57 (12) : 136-144 . |
| MLA | 周澄 et al. "基于神经网络和支持向量机的导波弯管腐蚀损伤程度辨识研究" . | 机械工程学报 57 . 12 (2021) : 136-144 . |
| APA | 周澄 , 邓菲 , 刘尧 , 刘秀成 , 陈洪磊 , 刘增华 . 基于神经网络和支持向量机的导波弯管腐蚀损伤程度辨识研究 . | 机械工程学报 , 2021 , 57 (12) , 136-144 . |
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摘要 ：
北京工业大学无损检测与评价研究所 2020年度研究进展
关键词 ：
机械工程 机械工程 硕士生 硕士生 拔尖创新人才 拔尖创新人才 结构健康监测 结构健康监测 硕士研究生 硕士研究生 北京工业大学 北京工业大学 创新团队 创新团队 波动特性 波动特性
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| GB/T 7714 | 刘增华 , 无损检测 . 北京工业大学无损检测与评价研究所 2020年度研究进展 [J]. | 刘增华 , 2021 , 43 (2) : 101-108 . |
| MLA | 刘增华 et al. "北京工业大学无损检测与评价研究所 2020年度研究进展" . | 刘增华 43 . 2 (2021) : 101-108 . |
| APA | 刘增华 , 无损检测 . 北京工业大学无损检测与评价研究所 2020年度研究进展 . | 刘增华 , 2021 , 43 (2) , 101-108 . |
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摘要 ：
This work presents a new omnidirectional electromagnetic acoustic transducer (EMAT) employing a circumferential periodic permanent magnet array, which was proposed for generating and receiving shear-horizontal (SH) guided waves in an aluminum plate. The novel transducer consisted of 12 axially polarized sector magnets arranged in a circle, and the magnetic field directions of adjacent magnets were opposite. A spiral coil was arranged under the magnet array. A vertical magnetic field generated by the magnets and the circumferential eddy current generated by the spiral coil formed a Lorentz force in a plate acting in the radial direction of this new omnidirectional EMAT. By controlling the sizes of the sector magnets, the omnidirectional SH0 mode (fundamental SH guided wave mode) was generated. To maximize the output of the EMAT at the given excitation frequency, it was proposed to add acrylic spacers between the sector magnets and determine the size of the magnet based on the frequency bandwidth of the excitation signal while also optimizing the omnidirectional sound field. A three-dimensional (3D) finite element model of the EMAT was established using COMSOL Multiphysics to perform numerical simulations, and the effectiveness of the optimization method was verified. The effectiveness was verified by experiments. The simulations and experiments showed that the proposed EMAT could generate omnidirectional SH0 mode guided waves in an aluminum plate. © 2001-2012 IEEE.
关键词 ：
Acoustic emission testing Acoustic emission testing Acoustic transducers Acoustic transducers Aluminum Aluminum Aluminum plating Aluminum plating Guided electromagnetic wave propagation Guided electromagnetic wave propagation Magnetic fields Magnetic fields Numerical methods Numerical methods Permanent magnets Permanent magnets Shear flow Shear flow
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| GB/T 7714 | Liu, Zenghua , Huo, Zhilin , Li, Aili et al. Development of an Omnidirectional SH0Mode Electromagnetic Acoustic Transducer Employing a Circumferential Periodic Permanent Magnet Array [J]. | IEEE Sensors Journal , 2021 , 21 (6) : 7691-7701 . |
| MLA | Liu, Zenghua et al. "Development of an Omnidirectional SH0Mode Electromagnetic Acoustic Transducer Employing a Circumferential Periodic Permanent Magnet Array" . | IEEE Sensors Journal 21 . 6 (2021) : 7691-7701 . |
| APA | Liu, Zenghua , Huo, Zhilin , Li, Aili , He, Cunfu , Wu, Bin . Development of an Omnidirectional SH0Mode Electromagnetic Acoustic Transducer Employing a Circumferential Periodic Permanent Magnet Array . | IEEE Sensors Journal , 2021 , 21 (6) , 7691-7701 . |
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摘要 ：
The quantification of damage, in plates, pipes and such like structures, is one of the current research areas. In this study, to estimate the notch size, shape, and orientation was carried out experimentally based on fundamental shear horizontal mode, SH0 mode. Using least number of transmitters, the reconstruction algorithm for the probabilistic inspection of damage (RAPID) has been used to carry out fast and efficient investigation of scattered waves using SH0 wave interaction with notch at various incident angles. An approach of ultrasonic guided waves and (RAPID) algorithm, using a direction-tunable shear-horizontal mode array magnetostrictive patch transducer (DT-SHMA-MPT), the notch in a thin aluminum plate is experimented. Firstly, the RAPID algorithm, based on SH0 mode, is used here to quantitatively study a notch in a thin aluminium plate. Secondly, the imaging application using DT-SHMA-MPT is achieved. Experiments were conducted using an array of eight DT-SHMA-MPTs based on a pitch-catch mode to utilize the scattered waves at the notch. The results obtained through experiments reveal the effect of directionality of the scattered waves and have find out the optimal transducers configuration. The localization, quantification and orientation at the same time are obtained using only two or three transmitters. To improve the accuracy of imaging, a threshold value was selected. The presented approach can be used to detect, locate and image the surface defects in aluminum plate. © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/).
关键词 ：
Aluminum Aluminum Aluminum plating Aluminum plating Engineering research Engineering research Guided electromagnetic wave propagation Guided electromagnetic wave propagation Plates (structural components) Plates (structural components) Shear flow Shear flow Surface defects Surface defects Transducers Transducers Transmitters Transmitters Ultrasonic applications Ultrasonic applications
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| GB/T 7714 | Ahmad, Mubarak , Liu, Zenghua , Basit, Abdul et al. Quantification of defects in an aluminum plate using direction-tunable shear horizontal wave imaging [C] . 2021 . |
| MLA | Ahmad, Mubarak et al. "Quantification of defects in an aluminum plate using direction-tunable shear horizontal wave imaging" . (2021) . |
| APA | Ahmad, Mubarak , Liu, Zenghua , Basit, Abdul , Jiang, Wenshuo , Bin, Wu , He, Cunfu . Quantification of defects in an aluminum plate using direction-tunable shear horizontal wave imaging . (2021) . |
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摘要 ：
Abstract: A large plate like structures can undergo some severe ruptures because of the stress created by the mass and shape. Ruptures are regularly started by surface cracks. For this aim, it is important to evaluate brutality of the noticeable cracks, by constant nondestructive assessments. In this work, a novel method for surface crack depth estimation based on Rayleigh waves by electromagnetic acoustic transducers (EMATs) is introduced. The method is based on a position-time (P-T) graph for direct transmitted Rayleigh waves between fixed transmitter and uniformly movable receiver on surface of the specimen. The process is repeated on different center frequencies both in the experiment as well as in two-dimensional finite element method simulation on steel plates. One of the specimens was without crack while the other one holds surface cracks with the depth ranging from 3–6 mm. Results obtained from simulation and experiment were significant to estimate crack depth with a maximum error of 7.5%. © 2020, Pleiades Publishing, Ltd.
关键词 ：
Acoustic emission testing Acoustic emission testing Crack propagation Crack propagation Plates (structural components) Plates (structural components) Rayleigh waves Rayleigh waves Surface defects Surface defects
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| GB/T 7714 | Basit, Abdul , Liu, Zenghua , Ahmad, Mubarak et al. A Novel Method for Evaluation of Surface Breaking Crack Using Position-Time Graph [J]. | Instruments and Experimental Techniques , 2021 , 64 (1) : 107-116 . |
| MLA | Basit, Abdul et al. "A Novel Method for Evaluation of Surface Breaking Crack Using Position-Time Graph" . | Instruments and Experimental Techniques 64 . 1 (2021) : 107-116 . |
| APA | Basit, Abdul , Liu, Zenghua , Ahmad, Mubarak , Wu, Bin , He, Cunfu . A Novel Method for Evaluation of Surface Breaking Crack Using Position-Time Graph . | Instruments and Experimental Techniques , 2021 , 64 (1) , 107-116 . |
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摘要 ：
Parameter estimation techniques based on chirplet models and intelligent algorithms can realize the simultaneous multi-information extraction of signals. They have attracted considerable attention for the processing of Lamb wave signals to detect defects and evaluate the material properties. Influenced by their dispersive nature, Lamb wave signals possess nonlinear instantaneous frequencies and asymmetric envelopes. However, the classical chirplet models are established with either Gaussian windows or linear chirps. They are inadequate for characterizing the dispersion features of ultrasonic signals whose excitations are modulated by Hanning windows. In our previous work, a nonlinear Hanning-windowed chirplet (NHWC) model with nine parameters was proposed to realize the full characterization of waveforms. However, the large number of parameters limits its application. A simple NHWC model with seven parameters was designed by submitting the same nonlinear phase modulation term into the Hanning-windowed sine function in this paper. Furthermore, a real-coded multi-objective genetic algorithm was developed to realize the parameter estimation of signals by combining a clustering algorithm and the NHWC model. Different strategies were adopted to ensure the convergence of the algorithm. The maximum extreme values were adopted to realize adaptive discretization of the search space and the updating of parameters. The parameters in the NHWC models were divided into implicit and explicit parts, and different strategies were applied to update them. The clustering algorithm and a sorting combination method were employed to generate a Pareto set. Experimental results showed that the parameter estimation with the simplified NHWC model exhibited a more robust performance than that of the model that contained nine parameters for characterizing the Lamb wave signals with or without the dispersion features. The arrival time, amplitude, and instantaneous frequencies of wave packets were identified with the parameter estimation technique. © 2020 Elsevier B.V.
关键词 ：
Clustering algorithms Clustering algorithms Dispersion (waves) Dispersion (waves) Frequency estimation Frequency estimation Genetic algorithms Genetic algorithms Nonlinear analysis Nonlinear analysis Signal analysis Signal analysis Surface waves Surface waves Ultrasonic applications Ultrasonic applications Ultrasonic waves Ultrasonic waves
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| GB/T 7714 | Chen, Honglei , Liu, Zenghua , Wu, Bin et al. A technique based on nonlinear Hanning-windowed chirplet model and genetic algorithm for parameter estimation of Lamb wave signals [J]. | Ultrasonics , 2021 , 111 . |
| MLA | Chen, Honglei et al. "A technique based on nonlinear Hanning-windowed chirplet model and genetic algorithm for parameter estimation of Lamb wave signals" . | Ultrasonics 111 (2021) . |
| APA | Chen, Honglei , Liu, Zenghua , Wu, Bin , He, Cunfu . A technique based on nonlinear Hanning-windowed chirplet model and genetic algorithm for parameter estimation of Lamb wave signals . | Ultrasonics , 2021 , 111 . |
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摘要 ：
A new design of Window Function modulated electromagnetic acoustic transducers (EMATs) to generate unidirectional Rayleigh waves is proposed. The novel EMATs, Rectangular-Window-Meander-Line-Coil EMATs (RWMLC-EMATs) and Kaiser-Window-Meander-Line-Coil EMATs (KWMLC-EMATs), contain two variable length meander line coils with a spacing of one quarter of Rayleigh waves' wavelength; the excitation signals for these two coils have a phase difference of 90 degrees. The structure of the variable wire length determines the level of the sidelobes suppression; the structure of two meander line coils combined with the excitation signals with a phase difference of 90 degrees determine that Rayleigh waves only propagate along one direction. RWMLC-EMATs and KWMLC-EMATs are analyzed via a wholly analytical method and are validated with experiments, which proves the feasibility of the proposed EMATs structure. In addition, the effect of the wire step and the longest wire length are investigated analytically and experimentally. Results indicate that, wire step mainly affects the suppressed level of sidelobes - a large wire step leads to a small suppressed level of sidelobes. This work can be used for Rayleigh waves EMATs design and optimization to improve their defect detection capability.
关键词 ：
Beam directivity Beam directivity Electromagnetic acoustic transducers (EMATs) Electromagnetic acoustic transducers (EMATs) Sidelobes suppression Sidelobes suppression Unidirectional Rayleigh waves Unidirectional Rayleigh waves Window function modulation Window function modulation
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| GB/T 7714 | Xie, Yuedong , Li, Jiyao , Huang, Pu et al. A novel design of window function modulated meander-line-coils EMATs for unidirectional Rayleigh waves generation and sidelobes suppression [J]. | NDT & E INTERNATIONAL , 2021 , 123 . |
| MLA | Xie, Yuedong et al. "A novel design of window function modulated meander-line-coils EMATs for unidirectional Rayleigh waves generation and sidelobes suppression" . | NDT & E INTERNATIONAL 123 (2021) . |
| APA | Xie, Yuedong , Li, Jiyao , Huang, Pu , Zhang, Le , Tian, Wenbin , Lu, Mingyang et al. A novel design of window function modulated meander-line-coils EMATs for unidirectional Rayleigh waves generation and sidelobes suppression . | NDT & E INTERNATIONAL , 2021 , 123 . |
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摘要 ：
In this research work, the parameters of the preset powder feeding laser cladding process of Ni60A-25% tungsten carbide (WC) powder were optimized by using the response surface methodology of the central composite design. The dilution rate eta and unit effective area phi of the laser cladding layer were considered as the response. Based on the factors and levels in the design matrix, the Ni60A-25% WC powder was fused on the 42CrMo alloy structural steel substrate with the laser cladding process to form a high-microhardness cladding layer. In this work, the microstructural characterization and crystal orientation analysis of the laser cladding layer obtained from the optimal process parameters were performed by using a Field Emission Scanning Electron Microscope (FE-SEM) and the Electron Backscatter Diffraction (EBSD) technique. The microhardness of the specimen processed with the optimal process parameters was evaluated using a Vickers microhardness tester. The results show the order of influence of four laser cladding process parameters on the dilution rate eta and unit effective area phi. The developed mathematical models for the dilution and the unit effective area were validated. The errors between the experimentally obtained dilution rate eta and unit effective area phi and predicted values were within acceptable limits. The EBSD analysis revealed that there was no meritocratic orientation of the substrate, while the laser cladding layer showed a pronounced meritocratic orientation. A large amount of martensite was produced within the coating after the laser cladding, resulting in a significant increase in the microhardness compared with the substrate. The microhardness test results were consistent with the microstructure morphology.
关键词 ：
EBSD EBSD Laser cladding Laser cladding Microhardness Microhardness Parameter optimization Parameter optimization Response surface methodology Response surface methodology
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| GB/T 7714 | Wu, Sha , Liu, Zenghua , Huang, Xiaofei et al. Process parameter optimization and EBSD analysis of Ni60A-25% WC laser cladding [J]. | INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS , 2021 , 101 . |
| MLA | Wu, Sha et al. "Process parameter optimization and EBSD analysis of Ni60A-25% WC laser cladding" . | INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS 101 (2021) . |
| APA | Wu, Sha , Liu, Zenghua , Huang, Xiaofei , Wu, Yufeng , Gong, Yu . Process parameter optimization and EBSD analysis of Ni60A-25% WC laser cladding . | INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS , 2021 , 101 . |
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摘要 ：
The use of ultrasonic longitudinal critically refracted (LCR) waves is one approach used for near surface material characterization. It has been shown to be sensitive to stress and, in general, less sensitive to the effects of the texture of the material. Although the LCR wave is increasingly widely applied, in experiments the factors that influence the formation of the LCR beam are seldom discussed. This paper reports a new numerical model used to investigate the transducers' parameters that can contribute to the directionality of the LCR wave and hence enable performance optimization when used for industrial applications. An orthogonal experimental method is used to study the sensitivity to the transducer parameters which influence the LCR wave beam characteristics. This method provides a design tool used to study and optimize multiple parameter experiments and it can identify which parameter or parameters are of most significance. The effects of incident angle, the aperture and the center frequency of the transducer were all studied. It is shown that the aperture of the transducer, the center frequency and the incident angle are the most important factors in controlling the directivity of the resulting LCR wave fields. The model was validated by comparision of data to those obtained with a finite element model. Experiments were also performed to confirm the numerical results. The model and experimental data provided improve understanding of the transducer selection and positioning in the optimization of LCR wave fields in experiments, which can be used to give signals which exhibit higher sensitivity for near-surface stress characterization.
关键词 ：
Directivity Directivity Longitudinal critically refracted (LCR) wave Longitudinal critically refracted (LCR) wave Models Models Orthogonal experimental method Orthogonal experimental method Residual stress Residual stress
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| GB/T 7714 | Pei Ning , Zhao Bin , Zhao Xin et al. Analysis of the directivity of Longitudinal Critically Refracted (LCR) waves. [J]. | Ultrasonics , 2021 , 113 : 106359 . |
| MLA | Pei Ning et al. "Analysis of the directivity of Longitudinal Critically Refracted (LCR) waves." . | Ultrasonics 113 (2021) : 106359 . |
| APA | Pei Ning , Zhao Bin , Zhao Xin , Liu Zenghua , Bond Leonard J . Analysis of the directivity of Longitudinal Critically Refracted (LCR) waves. . | Ultrasonics , 2021 , 113 , 106359 . |
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摘要 ：
Evolution of diverse Hall effects due to successive magnetic transitions has been observed in Mn2.5Fe0.6Sn0.9 by suitable chemical substitution of Fe in Mn3.1Sn0.9. This noncollinear antiferromagnetic alloy exhibits a Neel temperature of 325 K. Upon cooling from 325 K, a magnetic phase transition from noncollinear antiferromagnetism to ferromagnetism occurs at 168 K due to the tilting of magnetization towards c axis. Above this temperature, anomalous Hall resistivity ranged from 0.6 to 1.3 mu omega cm has been observed in noncollinear antiferromagnetic state. Below this temperature, a topological Hall effect (THE) starts to appear due to the non-vanishing scalar spin chirality arising from the noncoplanar spin structure. Further decreasing temperature to 132 K, another magnetic transition happens, resulting in the coexistence of ferromagnetism and antiferromagnetism, so that a Hall plateau with large hysteresis below 70 K is yielded. A hysteresis as high as similar to 80 kOe is obtained in rho(xy)-H at 15 K. However, the Hall plateau disappears and only anomalous Hall effect (AHE) persists when further decreasing the temperature to 5 K. The present study provides a picture of diverse magneto-transport properties correlated to the variable spin structures driven by magnetic phase transitions.
关键词 ：
anomalous Hall effect anomalous Hall effect non-collinear antiferromagnet non-collinear antiferromagnet topological Hall effect topological Hall effect
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| GB/T 7714 | Liu, Z. H. , Zhang, Q. Q. , Zhang, Y. J. et al. Evolution of diverse Hall effects during the successive magnetic phase transitions in Mn2.5Fe0.6Sn0.9 Kagome-lattice alloy [J]. | JOURNAL OF PHYSICS-CONDENSED MATTER , 2021 , 33 (11) . |
| MLA | Liu, Z. H. et al. "Evolution of diverse Hall effects during the successive magnetic phase transitions in Mn2.5Fe0.6Sn0.9 Kagome-lattice alloy" . | JOURNAL OF PHYSICS-CONDENSED MATTER 33 . 11 (2021) . |
| APA | Liu, Z. H. , Zhang, Q. Q. , Zhang, Y. J. , Zhang, H. G. , Ma, X. Q. , Liu, E. K. . Evolution of diverse Hall effects during the successive magnetic phase transitions in Mn2.5Fe0.6Sn0.9 Kagome-lattice alloy . | JOURNAL OF PHYSICS-CONDENSED MATTER , 2021 , 33 (11) . |
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