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Baek S, Kim G, Kim JY. Nonlinear standing waves for assessing material nonlinearity in thin samples. ULTRASONICS 2024; 142:107385. [PMID: 38936288 DOI: 10.1016/j.ultras.2024.107385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 05/06/2024] [Accepted: 06/18/2024] [Indexed: 06/29/2024]
Abstract
The second harmonic generation (SHG) technique offers a quantitative damage parameter known as the acoustic nonlinearity parameter (β) capable of detecting the change in the inherent material nonlinearity. However, current SHG methods, in particular, those used for measuring β in construction materials, have an unresolved issue in their application due to limited sample sizes. The restricted sample dimensions lead to the generation of boundary-reflected waves, which hinder the selective detection of propagating waves and thus the precise evaluation of material nonlinearity through β. Furthermore, the use of large samples limits the compatibility of the SHG method with other characterization modalities, such as mechanical tests, X-ray diffraction, and computerized tomography. To address this issue, this paper introduces a new SHG method that is based on the use of nonlinear standing waves - the dominant longitudinal standing waves in a forced-free configuration. The corrections for phase delay and attenuation effect of each reflected wave are made, enabling accurate measurements of β in thin samples with no requirement in the thickness-wavelength ratio. The measured β is then employed to quantify the microstructural modification in cement paste induced by thermal damage, validating the proposed method as a promising tool for quantifying microstructural changes in materials.
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Affiliation(s)
- Seungo Baek
- Department of Civil, Urban, Earth, and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulju-gun, Ulsan 44919, Republic of Korea.
| | - Gun Kim
- Department of Civil, Urban, Earth, and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulju-gun, Ulsan 44919, Republic of Korea.
| | - Jin-Yeon Kim
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
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Garcia N, Kim H, Vinod K, Sahoo A, Wax M, Kim T, Fang T, Narayanaswamy V, Wu H, Jiang X. Carbon nanofibers/liquid metal composites for high temperature laser ultrasound. ULTRASONICS 2024; 138:107245. [PMID: 38232449 DOI: 10.1016/j.ultras.2024.107245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Revised: 01/08/2024] [Accepted: 01/09/2024] [Indexed: 01/19/2024]
Abstract
As the demand for clean energy becomes greater worldwide, there will also be an increasing demand for next generation nuclear power plants that incorporate advanced sensors and monitoring equipment. A major challenge posed by nuclear power plants is that, during normal operation, the reactor compartment is subjected to high operating temperatures and radiation flux. Diagnostic sensors monitoring such structures are also subject to temperatures reaching hundreds of degrees Celsius, which puts them at risk for heat degradation. In this work, the ability of carbon nanofibers to work in conjunction with a liquid metal as a photoacoustic transmitter was demonstrated at high temperatures. Fields metal, a Bi-In-Sn eutectic, and gallium are compared as acoustic mediums. Fields metal was shown experimentally to have superior performance over gallium and other reference cases. Under stimulation from a low fluence 6 ns pulse laser at 6 mJ/cm2 with 532 nm green light, the Fields metal transducer transmitted a 200 kHz longitudinal wave with amplitude >5.5 times that generated by a gallium transducer at 300 °C. Each high temperature test was conducted from a hot to cold progression, beginning as high as 300 °C, and then cooling down to 100 °C. Each test shows increasing signal amplitude of the liquid metal transducers as temperature decreases. Carbon nanofibers show a strong improvement over previously used candle-soot nanoparticles in both their ability to produce strong acoustic signals and absorb higher laser fluences up to 12 mJ/cm2.
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Affiliation(s)
- Nicholas Garcia
- North Carolina State University, 1804 Entrepreneur Drive, Raleigh, NC 27606, USA
| | - Howuk Kim
- Inha University, Incheon, South Korea
| | - Kaushik Vinod
- North Carolina State University, 1804 Entrepreneur Drive, Raleigh, NC 27606, USA
| | - Abinash Sahoo
- North Carolina State University, 1804 Entrepreneur Drive, Raleigh, NC 27606, USA
| | - Michael Wax
- North Carolina State University, 1804 Entrepreneur Drive, Raleigh, NC 27606, USA
| | | | - Tiegang Fang
- North Carolina State University, 1804 Entrepreneur Drive, Raleigh, NC 27606, USA
| | - Venkat Narayanaswamy
- North Carolina State University, 1804 Entrepreneur Drive, Raleigh, NC 27606, USA
| | - Huaiyu Wu
- North Carolina State University, 1804 Entrepreneur Drive, Raleigh, NC 27606, USA
| | - Xiaoning Jiang
- North Carolina State University, 1804 Entrepreneur Drive, Raleigh, NC 27606, USA.
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