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12 pages, 11824 KiB

Open AccessArticle

Nondestructive Evaluation of Tensile Stress-loaded GFRPs Using the Magnetic Recording Method

by Ryszard D. Łukaszuk, Tomasz Chady, Marek J. Żwir and Krzysztof Gorący

Materials 2024, 17(1), 262; https://doi.org/10.3390/ma17010262 - 4 Jan 2024

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This paper presents the results of inspecting tensile stress-loaded GFRP (glass fiber-reinforced polymer) samples using the Magnetic Recording Method (MRM). The MRM can be utilized solely to examine ferromagnetic materials. The modification was proposed in order to examine nonmagnetic composites. Ferromagnetic strips made [...] Read more.

This paper presents the results of inspecting tensile stress-loaded GFRP (glass fiber-reinforced polymer) samples using the Magnetic Recording Method (MRM). The MRM can be utilized solely to examine ferromagnetic materials. The modification was proposed in order to examine nonmagnetic composites. Ferromagnetic strips made of low-carbon steel DC01 were bonded to the surface using an adhesive composed of epoxy resin with the addition of triethylenetetramine. The modified method’s feasibility was tested on six samples made of GFRP. The research procedure consisted of three steps. In the first step, a metal strip is glued at the top surface of each sample, and an array of 100 cylindrical permanent magnets is used to record a sinusoidal magnetic pattern on the strip. The initial residual magnetization is measured in the second step, and the samples are subjected to static stress. In the third step, the residual magnetization is measured one more time. Ultimately, the measurement results from the second and third steps are compared. Generally, the applied stress causes changes in the amplitude and frequency of the sinusoidal magnetization pattern. In the case of GFRP, the frequency changes have not been used for evaluation due to minimal variations. The statistical parameters (mean, median, max, and mode) of the RMS (root mean square) value of the sinusoidal pattern were calculated and analyzed. The analysis demonstrates that the modified method is suitable for providing unequivocal and exact information on the load applied to a nonmagnetic composite material. For the presented results, the applied load can be assessed unambiguously for the samples elongated up to 0.6%. Full article

(This article belongs to the Special Issue Advances in Nondestructive Evaluation of Materials and Structures)

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20 pages, 9931 KiB

Open AccessArticle

Exciting and Detecting Higher-Order Guided Lamb Wave Modes in High-Density Polyethylene Structures Using Ultrasonic Methods

by Justina Šeštokė, Elena Jasiūnienė, Reimondas Šliteris and Renaldas Raišutis

Materials 2024, 17(1), 163; https://doi.org/10.3390/ma17010163 - 28 Dec 2023

Viewed by 1002

Abstract

High-density polyethylene (HDPE) pipes are becoming increasingly popular, being used in various fields, such as construction, marine, petroleum, water transfer, process water, methane gas collection, oil and gas gathering, gas distribution systems, mining, acid and wet gas lines, offshore oil and gas and [...] Read more.

High-density polyethylene (HDPE) pipes are becoming increasingly popular, being used in various fields, such as construction, marine, petroleum, water transfer, process water, methane gas collection, oil and gas gathering, gas distribution systems, mining, acid and wet gas lines, offshore oil and gas and in nuclear power plants. Higher-order guided Lamb wave (UGW) modes can be used to detect various defects in complex structures. We will apply this methodology to one of the types of plastic—the structure of high-density polyethylene (HDPE). However, the excitation of UGW modes faces numerous challenges, especially when there is a need to identify which mode is excited. It is essential to note that, in the higher frequency range, multiple different higher-order modes can usually be excited. This can make it difficult to determine which modes have actually been excited. The objective of this research was to successfully excite and receive various higher-order UGW modes in high-density polyethylene structures using both ultrasonic single-element transducers and a phased array. Theoretical calculations were performed using a variety of methods: semi-analytical finite element (SAFE) method, 2D spatial–temporal spectrum analysis and finite element modeling (FEM). The results obtained from both measurements and simulations clearly demonstrate the possibility of efficiently exciting and receiving different Lamb wave modes possessing different phase velocities. Full article

(This article belongs to the Special Issue Advances in Nondestructive Evaluation of Materials and Structures)

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12 pages, 2150 KiB

Open AccessArticle

Development of Maximum Residual Stress Prediction Technique for Shot-Peened Specimen Using Rayleigh Wave Dispersion Data Based on Convolutional Neural Network

by Yeong-Won Choi, Taek-Gyu Lee, Yun-Taek Yeom, Sung-Duk Kwon, Hun-Hee Kim, Kee-Young Lee, Hak-Joon Kim and Sung-Jin Song

Materials 2023, 16(23), 7406; https://doi.org/10.3390/ma16237406 - 28 Nov 2023

Viewed by 1100

Abstract

Shot peening is a surface treatment process that improves the fatigue life of a material and suppresses cracks by generating residual stress on the surface. The injected small shots create a compressive residual stress layer on the material’s surface. Maximum compressive residual stress [...] Read more.

Shot peening is a surface treatment process that improves the fatigue life of a material and suppresses cracks by generating residual stress on the surface. The injected small shots create a compressive residual stress layer on the material’s surface. Maximum compressive residual stress occurs at a certain depth, and tensile residual stress gradually occurs as the depth increases. This process is primarily used for nickel-based superalloy steel materials in certain environments, such as the aerospace industry and nuclear power fields. To prevent such a severe accident due to the high-temperature and high-pressure environment, evaluating the residual stress of shot-peened materials is essential in evaluating the soundness of the material. Representative methods for evaluating residual stress include perforation strain gauge analysis, X-ray diffraction (XRD), and ultrasonic testing. Among them, ultrasonic testing is a representative, non-destructive evaluation method, and residual stress can be estimated using a Rayleigh wave. Therefore, in this study, the maximum compressive residual stress value of the peened Inconel 718 specimen was predicted using a prediction convolutional neural network (CNN) based on the relationship between Rayleigh wave dispersion and stress distribution on the specimen. By analyzing the residual stress distribution in the depth direction generated in the model from various studies in the literature, 173 residual stress distributions were generated using the Gaussian function and factorial design approach. The distribution generated using the relationship was converted into 173 Rayleigh wave dispersion data to be used as a database for the CNN model. The CNN model was learned through this database, and performance was verified using validation data. The adopted Rayleigh wave dispersion and convolutional neural network procedures demonstrate the ability to predict the maximum compressive residual stress in the peened specimen. Full article

(This article belongs to the Special Issue Advances in Nondestructive Evaluation of Materials and Structures)

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12 pages, 4277 KiB

Open AccessArticle

Reliability Analysis of PAUT Based on the Round-Robin Test for Pipe Welds with Thermal Fatigue Cracks

by Dongchan Kang, Yu Min Choi, Dong Min Lee, Jung Bin Kim, Yong Kwon Kim, Tae Sung Park and Ik Keun Park

Materials 2023, 16(21), 6908; https://doi.org/10.3390/ma16216908 - 27 Oct 2023

Cited by 2 | Viewed by 1304

Abstract

Thermal fatigue cracks occurring in pipes in nuclear power plants pose a high degree of risk. Thermal fatigue cracks are generated when the thermal fatigue load caused by local temperature gradients is repeatedly applied. The flaws are mainly found in welds, owing to [...] Read more.

Thermal fatigue cracks occurring in pipes in nuclear power plants pose a high degree of risk. Thermal fatigue cracks are generated when the thermal fatigue load caused by local temperature gradients is repeatedly applied. The flaws are mainly found in welds, owing to the effects of stress concentration caused by the material properties and geometric shapes of welds. Thermal fatigue pipes are classified as targets of risk-informed in-service inspection, for which ultrasonic testing, a volumetric non-destructive testing method, is applied. With the advancement of ultrasonic testing techniques, various studies have been conducted recently to apply the phased array ultrasonic testing (PAUT) method to the inspection of thermal fatigue cracks occurring on pipes. A quantitative reliability analysis of the PAUT method must be performed to apply the PAUT method to on-site thermal fatigue crack inspection. In this study, to evaluate the quantitative reliability of the PAUT method for thermal fatigue cracks, we fabricated crack specimens with the thermal fatigue mechanism applied to the pipe welds. We performed a round-robin test to collect PAUT data and determine the validity of the detection performance (probability of detection; POD) and the error in the sizing accuracy (root-mean-square error; RMSE) evaluation. The analysis results of the POD and sizing performance of the length and depth of thermal fatigue cracks were comparatively evaluated with the acceptance criteria of the American Society of Mechanical Engineers Code to confirm the effectiveness of applying the PAUT method. Full article

(This article belongs to the Special Issue Advances in Nondestructive Evaluation of Materials and Structures)

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13 pages, 4051 KiB

Open AccessEditor’s ChoiceArticle

Nondestructive Evaluation of Residual Stress in Shot Peened Inconel Using Ultrasonic Minimum Reflection Measurement

by Yeong-Won Choi, Taek-Gyu Lee, Yun-Taek Yeom, Sung-Duk Kwon, Hun-Hee Kim, Kee-Young Lee, Hak-Joon Kim and Sung-Jin Song

Materials 2023, 16(14), 5075; https://doi.org/10.3390/ma16145075 - 18 Jul 2023

Cited by 2 | Viewed by 1243

Abstract

Shot peening is a process wherein the surface of a material is impacted by small, spherical metal shots at high velocity to create residual stresses. Nickel-based superalloy is a material with high strength and hardness along with excellent corrosion and fatigue resistance, and [...] Read more.

Shot peening is a process wherein the surface of a material is impacted by small, spherical metal shots at high velocity to create residual stresses. Nickel-based superalloy is a material with high strength and hardness along with excellent corrosion and fatigue resistance, and it is therefore used in nuclear power plants and aerospace applications. The application of shot peening to INCONEL, a nickel-based superalloy, has been actively researched, and the measurement of residual stresses has been studied as well. Previous studies have used methods such as perforation strain gauge analysis and X-ray diffraction (XRD) to measure residual stress, which can be evaluated with high accuracy, but doing so damages the specimen and involves critical risks to operator safety due to radiation. On the other hand, ultrasonic testing (UT), which utilizes ultrasonic wave, has the advantage of relatively low unit cost and short test time. One UT method, minimum reflection measurement, uses Rayleigh waves to evaluate the properties of material surfaces. Therefore, the present study utilized ultrasonic minimum reflectivity measurements to evaluate the residual stresses in INCONEL specimens. Specifically, this study utilized ultrasonic minimum reflection measurements to evaluate the residual stress in INCONEL 718 specimens. Moreover, an estimation equation was assumed using exponential functions to estimate the residual stress with depth using the obtained data, and an optimization problem was solved to determine it. Finally, to evaluate the estimated residual stress graph, the residual stress of the specimen was measured and compared using the XRD method. Full article

(This article belongs to the Special Issue Advances in Nondestructive Evaluation of Materials and Structures)

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16 pages, 4331 KiB

Open AccessArticle

Measurement and In-Depth Analysis of Higher Harmonic Generation in Aluminum Alloys with Consideration of Source Nonlinearity

by Hyunjo Jeong, Hyojeong Shin, Shuzeng Zhang and Xiongbing Li

Materials 2023, 16(12), 4453; https://doi.org/10.3390/ma16124453 - 18 Jun 2023

Cited by 3 | Viewed by 1248

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 [...] Read more.

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 (

β^{2}

), 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

β^{2}

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

β^{2}

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

),

β^{2} \approx β * β

, the cubic nonlinearity parameters could be accurately determined even with thinner samples and lower input voltages. Full article

(This article belongs to the Special Issue Advances in Nondestructive Evaluation of Materials and Structures)

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13 pages, 5367 KiB

Open AccessArticle

Nearly Perfect Transmission of Lamé Modes in a Rectangular Beam with Part and Through-Thickness Vertical Cracks

by Xuwei Cao, Jing Ni, Chun Shao, Xiao Yang and Chenggan Lou

Materials 2023, 16(11), 4164; https://doi.org/10.3390/ma16114164 - 2 Jun 2023

Viewed by 1223

Abstract

The guided waves in the uniform waveguide of rectangular cross-section exhibit complicated propagation and scattering characteristics due to the diversity of vibration modes. This paper focuses on the mode conversion of the lowest Lamé mode at a part-through or through-thickness crack. Firstly, the [...] Read more.

The guided waves in the uniform waveguide of rectangular cross-section exhibit complicated propagation and scattering characteristics due to the diversity of vibration modes. This paper focuses on the mode conversion of the lowest Lamé mode at a part-through or through-thickness crack. Firstly, the Floquet periodicity boundary condition is applied to derive the dispersion curves in the rectangular beam, which relates the axial wavenumber to the frequency. On this basis, the frequency domain analysis is conducted to investigate the interaction between the fundamental longitudinal mode in the vicinity of the first Lamé frequency and a part-through or through-thickness vertical or inclined crack. Finally, the nearly perfect transmission frequency is evaluated by extracting displacement and stress harmonic fields throughout the cross-section. It is shown that this frequency originates from the first Lamé frequency, increases with the crack depth, and decreases with the crack width. Between them, the crack depth plays a major role in the frequency variation. In addition, the nearly perfect transmission frequency is negligibly affected by the beam thickness, and such a phenomenon is not observed for inclined cracks. The nearly perfect transmission may have potential applications in the quantitative evaluation of crack size. Full article

(This article belongs to the Special Issue Advances in Nondestructive Evaluation of Materials and Structures)

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19 pages, 16920 KiB

Open AccessArticle

Imaging of Fiber Waviness in Thick Composites with Unknown Material Properties Using Probability-Based Ultrasound Non-Reciprocity

by Zhen Zhang, Andong Cao, Qian Li, Weidong Yang and Yan Li

Materials 2023, 16(10), 3786; https://doi.org/10.3390/ma16103786 - 17 May 2023

Viewed by 1411

Abstract

Fiber waviness and voids may be produced in thick composites due to improper manufacturing conditions and consequently pose a risk of structural failure. A proof-of-concept solution for imaging fiber waviness in thick porous composites was proposed from both numerical and experimental studies, via [...] Read more.

Fiber waviness and voids may be produced in thick composites due to improper manufacturing conditions and consequently pose a risk of structural failure. A proof-of-concept solution for imaging fiber waviness in thick porous composites was proposed from both numerical and experimental studies, via calculating ultrasound non-reciprocity along different wave paths in a sensing network constructed by two phased array probes. Time-frequency analyses were conducted to reveal the cause of ultrasound non-reciprocity in wavy composites. Subsequently, the number of elements in the probes and excitation voltages was determined for fiber waviness imaging using the ultrasound non-reciprocity with a probability-based diagnostic algorithm. The fiber angle gradient was observed to cause ultrasound non-reciprocity and fiber waviness in the thick wavy composites were successfully imaged regardless of presence of voids. This study proposes a new feature for the ultrasonic imaging of fiber waviness and is expected to contribute to processing improvement in thick composites without prior knowledge of material anisotropy. Full article

(This article belongs to the Special Issue Advances in Nondestructive Evaluation of Materials and Structures)

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