| Thickness Determination for a Two-Layered Composite of a Film and a Plate by Low-Frequency Ultrasound |
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| 作者姓名： | 毛捷 李明轩 王小民 |
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| 作者单位： | Institute of Acoustics, Chinese Academy of Sciences, Beijing 100080 |
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| 基金项目： | Supported by the National Natural Science Foundation of China under Grant Nos 10474113 and 10234060. |
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| 摘 要： | We present an ultrasonic method for determining the thickness of a composite consisting of a soft thin film attached to a hard plate substrate, by resonance spectra in the low frequency region, The interrogating waves can be incident only to the two-layered composite from the substrate side. The reflection spectra are obtained by FFT analysis of the compressive pulsed echoes from the composite, and the thicknesses of the film and the substrate are simultaneously inversed by the simulated annealing method from the resonant frequencies knowing other acoustical parameters in prior. The sensitivity of the method to individual thickness, its convergence and stability against experimental noises are studied, Experiment with interrogating wavelength 4 times larger than the film thickness in a sample of a polymer film （0.054mm） on an aluminium plate （6.24mm） verifies the validity of the method. The average relative errors in the measurement of the thicknesses of the film and the substrate are found to be -4.1% and -0.62%, respectively.
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| 关 键 词： | 两分层复合材料 极板 超声波 厚度 |
| 收稿时间： | 2006-9-18 |
| 修稿时间： | 2006-09-18 |
Thickness Determination for a Two-Layered Composite of a Film and a Plate by Low-Frequency Ultrasound |
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| MAO Jie,LI Ming-Xuan,WANG Xiao-Min.Thickness Determination for a Two-Layered Composite of a Film and a Plate by Low-Frequency Ultrasound[J].Chinese Physics Letters,2007,24(3):755-758. |
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| Authors: | MAO Jie LI Ming-Xuan WANG Xiao-Min |
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| Institution: | Institute of Acoustics, Chinese Academy of Sciences, Beijing 100080 |
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| Abstract: | We present an ultrasonic method for determining the thickness of a composite consisting of a soft thin film attached to a hard plate substrate, by resonance spectra in the low frequency region. The interrogating waves can be incident only to the two-layered composite from the substrate side. The reflection spectra are obtained by FFT analysis of the compressive pulsed echoes from the composite, and the thicknesses of the film and the substrate are simultaneously inversed by the simulated annealing method from the resonant frequencies knowing other acoustical parameters in prior. The sensitivity of the method to individual thickness, its convergence and stability against experimental noises are studied. Experiment with interrogating wavelength 4 times larger than the film thickness in a sample of a polymer film (0.054mm) on an aluminium plate (6.24mm) verifies the validity of the method. The average relative errors in the measurement of the thicknesses of the film and the substrate are found to be -4.1% and -0.62%, respectively. |
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| Keywords: | 43 35 +d 43 60 +d |
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