| 1. |
- Diligent, O, et al.
(author)
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The low-frequency reflection and scattering of the S0 Lamb mode from a circular through-thickness hole in a plate: Finite Element, analytical and experimental studies
- 2002
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In: Journal of the Acoustical Society of America. - : Acoustical Society of America (ASA). - 1520-8524 .- 0001-4966. ; 112:6, s. 2589-2601
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Journal article (peer-reviewed)abstract
- A study of the interaction of the S0 Lamb wave with a circular through-thickness hole in a plate is presented. The study is limited to the nondispersive frequency range of this wave, in which the distributions of stress and displacement are simple. This allows a Finite Element analysis to be undertaken using a two-dimensional membrane discretization. Predictions of the direct reflection of the S0 mode and the lateral scattering of the SH0 mode are made for a range of diameters of the hole. At the same time, an analytical solution based on modal superposition is developed, and this is also used to predict the reflection and scattering coefficients. Both sets of predictions are validated by experimental measurements. It is found that the trends of the reflection coefficients for different hole diameters, frequencies and distances from the hole satisfy a simple normalization. On a detailed scale, the functions exhibit undulations which are shown to result from the interference of the direct reflection with secondary reflections which arrive slightly later.
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| 2. |
- Rydén, Nils, et al.
(author)
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Non-contact surface wave scanning of pavements using a rolling microphone array
- 2008
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In: Review of Progress in Quantitative Nondestructive Evaluation, vol 27A and 27B. - : AIP. - 0094-243X .- 1551-7616. ; 975, s. 1328-1332
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Conference paper (peer-reviewed)abstract
- We present experiments with a rolling multichannel microphone array where measurements can be taken continuously while moving. Leaky air-coupled surface waves are measured with ordinary non-directional audio microphones. Results show that microphones can be successfully used to produce a realistic phase velocity spectrum even while moving along the surface. The paper presents some theoretical background along with initial experimental results using the moving microphone array.
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| 3. |
- Rydén, Nils, et al.
(author)
-
Noncontact surface wave testing of pavements using microphones.
- 2008
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In: Journal of the Acoustical Society of America. - : Acoustical Society of America (ASA). - 1520-8524 .- 0001-4966. ; 124:4
-
Journal article (peer-reviewed)abstract
- Pavements are constructed using several layers of materials, and their durability depends mainly on the stiffness modulus and thickness of these strata. Surface wave testing is an effective tool to measure the stiffness and thickness of pavement layers. However, measurements are still based on spot testing with fixed receivers and source. The typical large size of pavements and the cost of closing down roads to make stationary testing makes these measurements impractical. We present experiments where a multichannel array of microphones and an automatic source are attached on a small trolley so that measurements can be taken almost continuously while moving. Measurements on asphalt or concrete pavement layers are based on supersonic leaky air-coupled surface waves. We also demonstrate that the same approach can be applied to softer granular pavement layers utilizing the seismic-to-acoustic coupling in poroelastic materials. Results show that microphones can be successfully used to measure correct surface wave dispersion curves even while moving along the surface. This opens up the possibility for faster on-the-fly surface wave testing of pavement layers since surface contact is no longer required. The theoretical background along with experimental results of the application to nondestructive testing of pavements will be presented.
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| 4. |
- Niemi, MEK, et al.
(author)
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- 2021
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swepub:Mat__t
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| 5. |
- Kanai, M, et al.
(author)
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- 2023
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swepub:Mat__t
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