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Verma B, Bélanger P. An alternative Rayleigh wave excitation method using an ultrasonic phased array. ULTRASONICS 2023; 135:107121. [PMID: 37572395 DOI: 10.1016/j.ultras.2023.107121] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 05/30/2023] [Accepted: 07/24/2023] [Indexed: 08/14/2023]
Abstract
Ultrasonic Rayleigh waves have been employed for in-service NDT inspection in a wide range of industries for years. The excitation of Rayleigh waves can be achieved using a variety of methods, with the so-called wedge technique being the most widely used. Recent years have seen considerable research interest in surface crack detection and sizing using Rayleigh waves excited and detected with the wedge technique. However, in this method, Rayleigh waves experience transmission loss at the wedge interfaces. Moreover, the flexibility to generate Rayleigh waves on different waveguides using the same wedge is limited, as the wedge angle depends on the Rayleigh wave wavelength. This work demonstrates a method that provides an alternative Rayleigh wave excitation method. In this, a conventional ultrasonic phased array transducer is used. As there is an appropriate excitation delay between each piezoelectric element of the array transducer, Rayleigh waves can be generated in a wide range of materials using the same phased array transducer. The delay can be estimated based on the elementary pitch of the transducer and the Rayleigh wave velocity of the waveguide. The proposed Rayleigh wave excitation method is demonstrated through both experiments and FE simulations. Furthermore, a finite element model is used to better understand the features of the generated waves and to validate them through their characteristics as Rayleigh wave. A quantitative comparison between the proposed and existing methods is also presented. The directivity and beam divergence of the generated Rayleigh waves are quantified. The results obtained from experiments are in agreement with finite element simulations and demonstrate the possibility of unidirectional and selective excitation of Rayleigh waves through the proposed method. They also highlight the potential for this new excitation method to be used to develop new Rayleigh wave-based inspection methods.
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Affiliation(s)
- Bhupesh Verma
- PULETS, Département de Génie Mécanique, École de technologie supérieure (ÉTS), 1100 Notre-Dame St. West, Montreal, Quebec H3C 1K3, Canada.
| | - Pierre Bélanger
- PULETS, Département de Génie Mécanique, École de technologie supérieure (ÉTS), 1100 Notre-Dame St. West, Montreal, Quebec H3C 1K3, Canada
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Jeong H, Shin H, Zhang S, Li X. Measurement and In-Depth Analysis of Higher Harmonic Generation in Aluminum Alloys with Consideration of Source Nonlinearity. MATERIALS (BASEL, SWITZERLAND) 2023; 16:4453. [PMID: 37374636 DOI: 10.3390/ma16124453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 06/12/2023] [Accepted: 06/16/2023] [Indexed: 06/29/2023]
Abstract
Harmonic generation measurement is recognized as a promising tool for inspecting material state or micro-damage and is an ongoing research topic. Second harmonic generation is most frequently employed and provides the quadratic nonlinearity parameter (β) that is calculated by the measurement of fundamental and second harmonic amplitudes. The cubic nonlinearity parameter (β2), which dominates the third harmonic amplitude and is obtained by third harmonic generation, is often used as a more sensitive parameter in many applications. This paper presents a detailed procedure for determining the correct β2 of ductile polycrystalline metal samples such as aluminum alloys when there exists source nonlinearity. The procedure includes receiver calibration, diffraction, and attenuation correction and, more importantly, source nonlinearity correction for third harmonic amplitudes. The effect of these corrections on the measurement of β2 is presented for aluminum specimens of various thicknesses at various input power levels. By correcting the source nonlinearity of the third harmonic and further verifying the approximate relationship between the cubic nonlinearity parameter and the square of the quadratic nonlinearity parameter (β∗β), β2≈β∗β, the cubic nonlinearity parameters could be accurately determined even with thinner samples and lower input voltages.
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Affiliation(s)
- Hyunjo Jeong
- Department of Mechanical Engineering, Wonkwang University, Iksan 54538, Republic of Korea
| | - Hyojeong Shin
- Graduate School of Flexible and Printable Electronics, Jeonbuk National University, Jeonju 54896, Republic of Korea
| | - Shuzeng Zhang
- School of Traffic and Transportation Engineering, Central South University, Changsha 410083, China
| | - Xiongbing Li
- School of Traffic and Transportation Engineering, Central South University, Changsha 410083, China
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3
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Kim C, Matlack KH. In situ nonlinear Rayleigh wave technique to characterize the tensile plastic deformation of stainless steel 316L. ULTRASONICS 2023; 131:106945. [PMID: 36805097 DOI: 10.1016/j.ultras.2023.106945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 10/27/2022] [Accepted: 01/31/2023] [Indexed: 06/18/2023]
Abstract
The acoustic nonlinearity parameter β is sensitive to dislocation parameters, which continuously change during plastic deformation. Dislocation-based damage in structures/components is the source of the failure; thus, β has been studied as a metric for non-destructive evaluation. This work consists of two parts: the development of an in situ experimental setup for nonlinear Rayleigh wave measurements, and characterization of the dependence of β on applied stress at different levels of initial plastic strain. First, we introduce an experimental setup and methods for repeatable in situ nonlinear ultrasonic measurements. Details on design considerations and measurement schemes are provided. In the second part, β was measured in situ during an incremental monotonic tensile test. The measured β monotonically decreases with plastic strain, but it is relatively insensitive to the applied stress during elastic deformation. This result highlights three aspects of the evolution of β, which have not been sufficiently emphasized in prior work: the apparent insensitivity of β to the applied stress during elastic deformation, decreasing β with plastic deformation, and the saturation of β. We attribute the trend of decreasing β to a scaling of β with monopole loop length during plastic deformation, which depends on initial microstructure. The saturation of β at 1.8% coincides with a planar-to-wavy transition of dislocation structures. The in situ nonlinear ultrasonic experimental method presented in this work is significant as the in situ results can provide broader insights on β and dislocation-based damage evolution than ex situ measurements alone.
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Affiliation(s)
- Changgong Kim
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | - Kathryn H Matlack
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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Bakre C, Lissenden CJ. Surface Roughness Effects on Self-Interacting and Mutually Interacting Rayleigh Waves. SENSORS 2021; 21:s21165495. [PMID: 34450938 PMCID: PMC8400126 DOI: 10.3390/s21165495] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/02/2021] [Accepted: 08/11/2021] [Indexed: 12/02/2022]
Abstract
Rayleigh waves are very useful for ultrasonic nondestructive evaluation of structural and mechanical components. Nonlinear Rayleigh waves have unique sensitivity to the early stages of material degradation because material nonlinearity causes distortion of the waveforms. The self-interaction of a sinusoidal waveform causes second harmonic generation, while the mutual interaction of waves creates disturbances at the sum and difference frequencies that can potentially be detected with minimal interaction with the nonlinearities in the sensing system. While the effect of surface roughness on attenuation and dispersion is well documented, its effects on the nonlinear aspects of Rayleigh wave propagation have not been investigated. Therefore, Rayleigh waves are sent along aluminum surfaces having small, but different, surface roughness values. The relative nonlinearity parameter increased significantly with surface roughness (average asperity heights 0.027–3.992 μm and Rayleigh wavelengths 0.29–1.9 mm). The relative nonlinearity parameter should be decreased by the presence of attenuation, but here it actually increased with roughness (which increases the attenuation). Thus, an attenuation-based correction was unsuccessful. Since the distortion from material nonlinearity and surface roughness occur over the same surface, it is necessary to make material nonlinearity measurements over surfaces having the same roughness or in the future develop a quantitative understanding of the roughness effect on wave distortion.
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Song DG, Choi S, Kim T, Jhang KY. Compensation of a Second Harmonic Wave Included in an Incident Ultrasonic Wave for the Precise Measurement of the Acoustic Nonlinearity Parameter. SENSORS 2021; 21:s21093203. [PMID: 34063065 PMCID: PMC8125425 DOI: 10.3390/s21093203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 04/28/2021] [Accepted: 04/30/2021] [Indexed: 11/16/2022]
Abstract
The incident second harmonic wave is a problematic issue for the precise measurement of the acoustic nonlinearity parameter. This paper proposes a compensation method to remove the effect of the incident second harmonic component in the measurement of the absolute acoustic nonlinearity parameter using the calibration method. For this, the second harmonic component detected by the receiving transducer is considered as the sum of the component due to material nonlinearity and the component included in the incident signal and a numerical calculation model is developed as a function of the propagation distance. In the model, the factors related to the material nonlinear parameter and the magnitude of the incident second harmonic component are unknown and these are determined by finding a value that best matches the experimental data according to the change in the propagation distance; compensation for the incident second harmonic component is then achieved. The case where the phase of the second harmonic wave due to material nonlinearity is opposite to that of the fundamental wave is also considered. To verify the validity of the proposed method, fused silica and aluminum alloy Al6061-T6 specimens with different thicknesses corresponding to the propagation distance are tested. The experimental results show that the nonlinear parameters changed significantly according to the propagation distance before compensation but were very stable after compensation. Additionally, the average values of the nonlinear parameter are 11.04 in the fused silica, which is within the literature value range (10.1 to 12.4), and that for the Al6061-T6 is 6.59, which is close to the literature value range (4.5 to 6.12).
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Affiliation(s)
- Dong-Gi Song
- Department of Mechanical Convergence Engineering, Hanyang University, Seoul 04763, Korea;
| | - Sungho Choi
- LANL-JBNU Engineering Institute-Korea, Jeonbuk National University, Jeollabuk-do 54896, Korea;
| | - Taehyeon Kim
- Radiation and Decommissioning Laboratory, KHNP-CRI, Daejeon 34101, Korea;
| | - Kyung-Young Jhang
- School of Mechanical Engineering, Hanyang University, Seoul 04763, Korea
- Correspondence: ; Tel.: +82-2220-0434; Fax: +82-2299-7207
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Jeong H, Cho S, Zhang S, Li X. Absolute Measurement of Material Nonlinear Parameters Using Noncontact Air-Coupled Reception. MATERIALS (BASEL, SWITZERLAND) 2021; 14:E244. [PMID: 33419011 PMCID: PMC7825340 DOI: 10.3390/ma14020244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 12/29/2020] [Accepted: 12/31/2020] [Indexed: 11/29/2022]
Abstract
Nonlinear ultrasound is often employed to assess microdamage or nonlinear elastic properties of a material, and the nonlinear parameter is commonly used to quantify damage sate and material properties. Among the various factors that influence the measurement of nonlinear parameters, maintaining a constant contact pressure between the receiver and specimen is important for repeatability of the measurement. The use of an air-coupled transducer may be considered to replace the contact receiver. In this paper, a method of measuring the relative and absolute nonlinear parameters of materials is described using an air-coupled transducer as a receiver. The diffraction and attenuation corrections are newly derived from an acoustic model for a two-layer medium and the nonlinear parameter formula with all corrections is defined. Then, we show that the ratio of the relative nonlinear parameter of the target sample to the reference sample is equal to that of the absolute nonlinear parameter, and this equivalence is confirmed by measurements on three systems of aluminum samples. The proposed method allows the absolute measurement of the nonlinear parameter ratio or the nonlinear parameter without calibration of the air-coupled receiver and removes restrictions on the selection of reference samples.
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Affiliation(s)
- Hyunjo Jeong
- Department of Mechanical Engineering, Wonkwang University, Iksan, Jeonbuk 54538, Korea
| | - Sungjong Cho
- Nondestructive Testing (NDT) Research Center, Seoul National University of Science and Technology, Seoul 01811, Korea;
| | - Shuzeng Zhang
- School of Traffic and Transportation Engineering, Central South University, Changsha 410075, China; (S.Z.); (X.L.)
| | - Xiongbing Li
- School of Traffic and Transportation Engineering, Central South University, Changsha 410075, China; (S.Z.); (X.L.)
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Bellotti A, Kim JY, Bishop JE, Jared BH, Johnson K, Susan D, Noell PJ, Jacobs LJ. Nonlinear ultrasonic technique for the characterization of microstructure in additive materials. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2021; 149:158. [PMID: 33514167 DOI: 10.1121/10.0002960] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 12/03/2020] [Indexed: 06/12/2023]
Abstract
This study employs nonlinear ultrasonic techniques to track microstructural changes in additively manufactured metals. The second harmonic generation technique based on the transmission of Rayleigh surface waves is used to measure the acoustic nonlinearity parameter, β. Stainless steel specimens are made through three procedures: traditional wrought manufacturing, laser-powder bed fusion, and laser engineered net shaping. The β parameter is measured through successive steps of an annealing heat treatment intended to decrease dislocation density. Dislocation density is known to be sensitive to manufacturing variables. In agreement with fundamental material models for the dislocation-acoustic nonlinearity relationship in the second harmonic generation, β drops in each specimen throughout the heat treatment before recrystallization. Geometrically necessary dislocations (GNDs) are measured from electron back-scatter diffraction as a quantitative indicator of dislocations; average GND density and β are found to have a statistical correlation coefficient of 0.852 showing the sensitivity of β to dislocations in additively manufactured metals. Moreover, β shows an excellent correlation with hardness, which is a measure of the macroscopic effect of dislocations.
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Affiliation(s)
- Aurelio Bellotti
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Jin-Yeon Kim
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Joseph E Bishop
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - Bradley H Jared
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - Kyle Johnson
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - Donald Susan
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - Philip J Noell
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - Laurence J Jacobs
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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Measurement of the Acoustic Non-Linearity Parameter of Materials by Exciting Reversed-Phase Rayleigh Waves in Opposite Directions. SENSORS 2020; 20:s20071955. [PMID: 32244379 PMCID: PMC7180907 DOI: 10.3390/s20071955] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 03/28/2020] [Accepted: 03/30/2020] [Indexed: 11/17/2022]
Abstract
The acoustic non-linearity parameter of Rayleigh waves can be used to detect various defects (such as dislocation and micro-cracks) on material surfaces of thick-plate structures; however, it is generally low and likely to be masked by noise. Moreover, conventional methods used with non-linear Rayleigh waves exhibit a low detection efficiency. To tackle these problems, a method of exciting reversed-phase Rayleigh waves in opposite directions is proposed to measure the acoustic non-linearity parameter of materials. For that, two angle beam wedge transducers were placed at the two ends of the upper surface of a specimen to excite two Rayleigh waves of opposite phases, while a normal transducer was installed in the middle of the upper surface to receive them. By taking specimens of 0Cr17Ni4Cu4Nb martensitic stainless steel subjected to fatigue damage as an example, a finite element simulation model was established to test the proposed method of measuring the acoustic non-linearity parameter. The simulation results show that the amplitude of fundamentals is significantly reduced due to offset, while that of second harmonics greatly increases due to superposition because of the opposite phases of the excited signals, and the acoustic non-linearity parameter thus increases. The experimental research on fatigue damage specimens was carried out using this method. The test result was consistent with the simulation result. Thus, the method of exciting reversed-phase Rayleigh waves in opposite directions can remarkably increase the acoustic non-linearity parameter. Additionally, synchronous excitation with double-angle beam wedge transducers can double the detection efficiency.
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Nondestructive Evaluation of Thermal Aging in Al6061 Alloy by Measuring Acoustic Nonlinearity of Laser-Generated Surface Acoustic Waves. METALS 2019. [DOI: 10.3390/met10010038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The structures in high-temperature environments are prone to undergo hardening and embrittlement as a result of thermal aging; this can cause variations in their mechanical properties. Because these changes occur at the microstructural level, it is difficult to evaluate them through linear ultrasonic techniques. In this work, a surface acoustic wave (SAW) was used to measure and compare the acoustic nonlinearity and mechanical properties of Al6061 alloys heat-treated at 220 °C for different durations (0 min, 20 min, 40 min, 1 h, 2 h, 10 h, 100 h, 1000 h). The SAW was generated by a pulsed laser and then received by an interferometer. Moreover, the yield strength, ultimate strength, and elongation to failure were measured by tensile tests. The results demonstrate that the critical variations in the mechanical properties can be detected by monitoring the variation features in the acoustic nonlinearity. Transmission electron microscopy images were captured to observe the microstructural changes, which shows that the acoustic nonlinearity varied according to the change in the precipitation phase. This supports the acoustic nonlinearity measurement using the laser-generated SAW being an effective technique for the fully noncontact nondestructive evaluation of material degradations as well as changes in mechanical properties.
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Zhang S, Li X, Jeong H, Hu H. Experimental investigation of material nonlinearity using the Rayleigh surface waves excited and detected by angle beam wedge transducers. ULTRASONICS 2018; 89:118-125. [PMID: 29778060 DOI: 10.1016/j.ultras.2018.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Revised: 05/11/2018] [Accepted: 05/11/2018] [Indexed: 06/08/2023]
Abstract
Angle beam wedge transducers are widely used in nonlinear Rayleigh wave experiments as they can generate Rayleigh wave easily and produce high intensity nonlinear waves for detection. When such a transducer is used, the spurious harmonics (source nonlinearity) and wave diffraction may occur and will affect the measurement results, so it is essential to fully understand its acoustic nature. This paper experimentally investigates the nonlinear Rayleigh wave beam fields generated and received by angle beam wedge transducers, in which the theoretical predictions are based on the acoustic model developed previously for angle beam wedge transducers [S. Zhang, et al., Wave Motion, 67, 141-159, (2016)]. The source of the spurious harmonics is fully characterized by scrutinizing the nonlinear Rayleigh wave behavior in various materials with different driving voltages. Furthermore, it is shown that the attenuation coefficients for both fundamental and second harmonic Rayleigh waves can be extracted by comparing the measurements with the predictions when the experiments are conducted at many locations along the propagation path. A technique is developed to evaluate the material nonlinearity by making appropriate corrections for source nonlinearity, diffraction and attenuation. The nonlinear parameters of three aluminum alloy specimens - Al 2024, Al 6061 and Al 7075 - are measured, and the results indicate that the measurement results can be significantly improved using the proposed method.
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Affiliation(s)
- Shuzeng Zhang
- School of Traffic and Transportation Engineering, Central South University, Changsha, Hunan 410075, China
| | - Xiongbing Li
- School of Traffic and Transportation Engineering, Central South University, Changsha, Hunan 410075, China.
| | - Hyunjo Jeong
- Department of Mechanical Engineering, Wonkwang University, Iksan, Jeonbuk 54538, Republic of Korea
| | - Hongwei Hu
- College of Automotive and Mechanical Engineering, Changsha University of Science and Technology, Changsha, Hunan 410114, China
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Mora P, Spies M. Rayleigh wave harmonic generation in materials with depth-dependent non-linear properties. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2018; 143:2678. [PMID: 29857750 DOI: 10.1121/1.5036732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Non-linear Rayleigh waves are investigated theoretically in materials having inhomogeneous third order and homogeneous second order elastic properties. Compared to the complete homogeneous case, the constants coupling the harmonics turn out to depend on frequency. The sensitivity and selectivity to the three Murnaghan's constants is discussed considering mono- and bi-chromatic inputs in the mark of the quasi-linear approximation. Numerical examples are given for depth profiles characteristic of dislocation densities in shot-peened metals. The predicted low-frequency scales are consistent with observation recently reported.
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Affiliation(s)
- Pierric Mora
- Fraunhofer-Institute for Nondestructive Testing IZFP, Campus E3 1, 66123 Saarbrücken, Germany
| | - Martin Spies
- Fraunhofer-Institute for Nondestructive Testing IZFP, Campus E3 1, 66123 Saarbrücken, Germany
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Generation Mechanism of Nonlinear Rayleigh Surface Waves for Randomly Distributed Surface Micro-Cracks. MATERIALS 2018; 11:ma11040644. [PMID: 29690580 PMCID: PMC5951528 DOI: 10.3390/ma11040644] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 04/19/2018] [Accepted: 04/19/2018] [Indexed: 11/21/2022]
Abstract
This paper investigates the propagation of Rayleigh surface waves in structures with randomly distributed surface micro-cracks using numerical simulations. The results revealed a significant ultrasonic nonlinear effect caused by the surface micro-cracks, which is mainly represented by a second harmonic with even more distinct third/quadruple harmonics. Based on statistical analysis from the numerous results of random micro-crack models, it is clearly found that the acoustic nonlinear parameter increases linearly with micro-crack density, the proportion of surface cracks, the size of micro-crack zone, and the excitation frequency. This study theoretically reveals that nonlinear Rayleigh surface waves are feasible for use in quantitatively identifying the physical characteristics of surface micro-cracks in structures.
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Zhang S, Li X, Jeong H. Measurement of Rayleigh Wave Beams Using Angle Beam Wedge Transducers as the Transmitter and Receiver with Consideration of Beam Spreading. SENSORS 2017. [PMID: 28632183 PMCID: PMC5492238 DOI: 10.3390/s17061449] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
A theoretical model, along with experimental verification, is developed to describe the generation, propagation and reception of a Rayleigh wave using angle beam wedge transducers. The Rayleigh wave generation process using an angle beam wedge transducer is analyzed, and the actual Rayleigh wave sound source distributions are evaluated numerically. Based on the reciprocity theorem and considering the actual sound source, the Rayleigh wave beams are modeled using an area integral method. The leaky Rayleigh wave theory is introduced to investigate the reception of the Rayleigh wave using the angle beam wedge transducers, and the effects of the wave spreading in the wedge and transducer size are considered in the reception process. The effects of attenuations of the Rayleigh wave and leaky Rayleigh wave are discussed, and the received wave results with different sizes of receivers are compared. The experiments are conducted using two angle beam wedge transducers to measure the Rayleigh wave, and the measurement results are compared with the predictions using different theoretical models. It is shown that the proposed model which considers the wave spreading in both the sample and wedges can be used to interpret the measurements reasonably.
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Affiliation(s)
- Shuzeng Zhang
- School of Traffic and Transportation Engineering, Central South University, Changsha 410075, China.
| | - Xiongbing Li
- School of Traffic and Transportation Engineering, Central South University, Changsha 410075, China.
| | - Hyunjo Jeong
- Division of Mechanical and Automotive Engineering, Wonkwang University, Iksan 570-749, Korea.
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14
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Characterizing Hypervelocity Impact (HVI)-Induced Pitting Damage Using Active Guided Ultrasonic Waves: From Linear to Nonlinear. MATERIALS 2017; 10:ma10050547. [PMID: 28772908 PMCID: PMC5459012 DOI: 10.3390/ma10050547] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 04/27/2017] [Accepted: 05/09/2017] [Indexed: 11/30/2022]
Abstract
Hypervelocity impact (HVI), ubiquitous in low Earth orbit with an impacting velocity in excess of 1 km/s, poses an immense threat to the safety of orbiting spacecraft. Upon penetration of the outer shielding layer of a typical two-layer shielding system, the shattered projectile, together with the jetted materials of the outer shielding material, subsequently impinge the inner shielding layer, to which pitting damage is introduced. The pitting damage includes numerous craters and cracks disorderedly scattered over a wide region. Targeting the quantitative evaluation of this sort of damage (multitudinous damage within a singular inspection region), a characterization strategy, associating linear with nonlinear features of guided ultrasonic waves, is developed. Linear-wise, changes in the signal features in the time domain (e.g., time-of-flight and energy dissipation) are extracted, for detecting gross damage whose characteristic dimensions are comparable to the wavelength of the probing wave; nonlinear-wise, changes in the signal features in the frequency domain (e.g., second harmonic generation), which are proven to be more sensitive than their linear counterparts to small-scale damage, are explored to characterize HVI-induced pitting damage scattered in the inner layer. A numerical simulation, supplemented with experimental validation, quantitatively reveals the accumulation of nonlinearity of the guided waves when the waves traverse the pitting damage, based on which linear and nonlinear damage indices are proposed. A path-based rapid imaging algorithm, in conjunction with the use of the developed linear and nonlinear indices, is developed, whereby the HVI-induced pitting damage is characterized in images in terms of the probability of occurrence.
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