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国家自然科学基金(10574138)

作品数:6 被引量:25H指数:3
相关作者:王小民李明轩陈秋颖毛捷黄振俨更多>>
相关机构:中国科学院更多>>
发文基金:国家自然科学基金更多>>
相关领域:理学一般工业技术金属学及工艺更多>>

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6 条 记 录,以下是 1-9
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Sound field of an electromagnetic acoustic transducer被引量:6
2011年
The characteristic of radiated sound field excitated within a non-ferromagnetic aluminum by an electromagnetic acoustic transducer consisting of circle-spiral coil and vertical bias magnetic field is studied. This article presents an improved force source model according to the principle of electromagnetic induction. Then the analytic displacement solution of sound field produced by that force source model is deduced. The tangential and normal directivities of shear and longitudinal sounds are calculated numerically and compared with experimental results. Experimental results conform well to the theoretical prediction, which not only shows that the electromagnetic acoustic transducer of this conformation has a good directivity of vertical shear-wave radiation, but also confirms the given force source model is effective to describe the actual physical behavior of the probe. Theoretical and experimental study lays a foundation for optimization design and engineering application of the electromagnetic acoustic probe.
CHEN Qiuying WANG Xiaomin LI Mingxuan MAO Jie
Ultrasonic field radiated by a normal shear wave probe被引量:1
2007年
The field of horizontally polarized ultrasonic shear wave radiated by a 2/2 piezoelectric composite normal probe was studied. The strictly analytic field solutions for two different surface forces were deduced and the field distribution and directivity patterns were given by numerical calculations. The vertical radiated field of shear wave was obtained theoretically and compared with experiment. The experimental result of directivity pattern conformed the theoretical prediction, which provided the theoretical basis for the engineering application of the transducer.
WU Di LI Mingxuan WANG Xiaomin CHENG Yue
横波直探头声场特性的实验研究
<正>横波检测广泛应用于工业无损检测中,通常是用斜探头通过楔块将压电晶片产生的纵波转换为横波, 也可以用一般的压电晶片在正交场下产生横波,这两种横波都是垂直偏振横波(SV波),这类横波在传播时遇到界面会产生波模转换,而S...
吴迪宋卫华李明轩王小民
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电磁声换能器的辐射声场研究被引量:11
2009年
分析了一种圆环形螺线圈、垂直偏置磁场结构的电磁声探头在非铁磁性介质铝中的辐射声场特性。首先根据电磁感应原理对探头进行了物理和数学建模,将表面力源近似成水平和竖直分布的两种,且水平分量远大于竖直分量,推导出该种力源产生的声场的理论解析解。分别数值计算出了横波和纵波的切向和法向指向性,并和实验结果进行对比。实验结果和理论计算符合较好,为此种结构的电磁声换能器的实际工程应用提供了理论依据。
陈秋颖王小民李明轩毛捷
关键词:辐射声场电磁感应原理声场特性数学建模
Analysis and identification for the electromagnetic ultrasonic interfacial echoes using instantaneous spectrum and artificial neural network被引量:2
2008年
The proper frequency is experimentally chosen to be the operation frequency of the electromagnetic acoustic transducer. The instantaneous amplitude, phase and frequency of the detected ultrasonic echoes from a multilayer adhesive sample of steel and rubber materials are calculated and composed to form three-dimensional instantaneous spectrum which is successful to distinguish the testing signals from different adhesive states qualitatively. Then, average instantaneous parameters in sensitive time window are picked up and used as the input eigenvectors for the BP artificial neural network. Identified results in both training and testing volumes demonstrate that the detected electromagnetic ultrasonic interracial echoes can be identified and classified automatically with the correctness ratio larger than 95%.
SONG WeihuaWANG XiaominLI Mingxuan
层状介质超声实验回波瞬时图谱分析与识别
<正>层状粘接结构在现代工业中被广泛地应用,对层状粘接结构的无损检测与评价的需求日益增加,在无损检测与评价的方法和技术中,信号处理方法和技术所占的比重越来越高。本文针对含气体夹层脱粘的层状粘接结构超声检测回波,尝试一种新...
宋卫华王小民李明轩
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电磁声发射换能响应特性实验研究
<正>1引言有关电磁声换能器(Electromagnetic Acoustic Transducer-EMAT)性能分析的研究比较少,且主要集中于在电磁力表面力源条件下研究换能器的暂态辐射声场特性和等效电阻抗特性等两个方...
宋卫华王小民李明轩
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电磁声实验平台的研制与实验研究被引量:9
2009年
研制了一个多功能的电磁声实验平台,在此实验平台,进行了"减小盲区"、"钢层下多层橡胶层脱粘检测"、"线性调频脉冲压缩"等方面的实验研究。实验结果表明,该平台可精确控制实验参数,提供单一频率脉冲串和线性调频脉冲两种激励波形,具有信噪比高盲区小的优点和线性调频脉冲压缩的功能。将该实验平台应用在钢层与多层橡胶层粘接件的脱粘检测,取得了与压电检测相当的结果。作为一个电磁声方法和技术研究的工具,该实验平台对开展电磁声检测方法和技术研究以及实际检测应用都是有意义的。
冷涛李明轩黄振俨王小民
关键词:线性调频脉冲脉冲压缩精确控制橡胶层
Study on the denoising method for the electromagnetic ultrasonic echoes from multiple interfaces被引量:3
2008年
The electromagnetic ultrasound is used in the detection of interfaces of the adhesive multilayer structures to solve the unstable coupling problem in ultrasonic testing by traditional piezoelectric transducers. Based on the analysis of the transforming mechanism of electromag-netic ultrasound energy and the resultant dead zone from mutual inductance of the transducer, the wavelet filtering by soft-thresholding and adaptive noise canceling methods are used simul-taneously to the detected electromagnetic ultrasonic signals to overcome the drawbacks of the low signal to noise ratio (SNR) and the wide intrinsic dead zone of the transducer. Processed results in the interface detection of a three layered adhesive sample of steel and rubber materials demonstrate that the wavelet filtering enhances the SNR about 12dB while the adaptive noise canceling narrows the dead zone effectively.
SONG WeihuaWANG XiaominLI Mingxuan
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