scholarly journals Analysis of Linear Non-Destructive Testing and Evaluation Methods for Thin-Walled Structure Inspection Using Ultrasonic Array

Coatings ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 146
Author(s):  
Yang Li ◽  
Zhenggan Zhou ◽  
Jun Wang
Keyword(s):  
Signal To Noise Ratio ◽  
Near Field ◽  
Central Frequency ◽  
Destructive Testing ◽  
Array Transducer ◽  
Imaging Results ◽  
Ultrasonic Array ◽  
Thin Walled ◽  
Aluminum Plates ◽  
Non Destructive

The ultrasonic array used for thin-walled structure non-destructive inspection usually has a high central frequency so that the thickness-to-acoustic wavelength ratio is greater than 10. When the ratio is much smaller than 10, the reliability of the conventional ultrasonic array method will dramatically decrease due to the influence of the acoustic near-field. This situation is unavoidable since the available central frequency of the array transducer cannot be an arbitrarily large value. To optimize the inspection performance in this case, the testing of an ultrasonic array and the evaluation of a structure whose thickness is smaller than five-times the longitudinal wavelength are analyzed in this paper. Linear ultrasonic array methods using different combinations of wave patterns, reflection times, and coupling conditions are uniformly expressed as full matrix algorithms. Simulated and experimental full matrices of 6 mm-thick aluminum plates using a 5-MHz array transducer are captured to analyze their imaging performances and sizing abilities with respect to various defects. Analyses show that the inspection results of the wedge coupling method have a much higher signal-to-noise ratio (SNR) than the results of conventional direct contact methods. Circular defects and rectangular defects can be distinguished by comparing the imaging results of different modes. For the simulated circular defect, the diameter can be measured according to the maximum image amplitude of the defect. To simulate a rectangular defect located in the lower half of the region, the nominal length can be measured using a linear function whose input is a −6 dB drop in length of the SS-S mode image. For a real sample, the material anisotropy and complex self-reflections will decrease the SNR by about 10 dB.

scholarly journals Application of Ultrasonic Array Method for the Inspection of TC18 Addictive Manufacturing Titanium Alloy

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4371 ◽  
Author(s):  
Wentao Li ◽  
Zhenggan Zhou ◽  
Yang Li
Keyword(s):  
Titanium Alloy ◽  
Three Dimensional ◽  
Imaging Method ◽  
Destructive Testing ◽  
Flat Bottom ◽  
Annular Array ◽  
Array Transducer ◽  
Ultrasonic Array ◽  
Testing Technology ◽  
Non Destructive

Ultrasonic arrays have been investigated for inspecting the quality of special materials. Unfortunately, non-destructive testing and evaluation (NDT&E) of internal defects in additive manufacturing (AM) materials are difficult due to the anisotropy and the coarse grain. To solve the problem, this paper brings forward research on the inspection of TC18 AM titanium alloy products using an ultrasonic array. Firstly, a three-dimensional acoustic field distribution of different ultrasonic array transducers is established to design an optimal detection solution for an AM titanium alloy. Then, a total focusing method (TFM) for the ultrasonic annular array transducer is proposed and its imaging method is analyzed. Besides, the relation between ultrasonic group velocities in a TC18 AM specimen with different propagating angles is measured using the full matrix capture (FMC) method. Based on the measurements, the anisotropy of the AM titanium alloy is discussed and the TFM algorithm of annular array is optimized as well. Finally, C-scan experiments are conducted on the specimen with a height of 55 mm using the linear ultrasonic array transducer of the conventional focusing method and the TFM of annular array transducer, respectively. The results show that the TFM of annular array has higher accuracy in quantifying the defects of flat bottom holes and transverse holes with a diameter of 0.8 mm. In addition, the detection results of different forming directions are analyzed and the 3D imaging of defects in the specimen is realized based on FMC data. The TFM of annular array is an innovative ultrasonic testing technology with high resolution for AM titanium alloy products.

Laser Monitors for High Speed Imaging of Plasma, Beam and Discharge Processes

2016 ◽  
Vol 712 ◽  
pp. 303-307 ◽  
Author(s):  
Maxim V. Trigub ◽  
Stanislav N. Torgaev ◽  
Gennadiy S. Evtushenko ◽  
Vitaliy V. Drobchik
Keyword(s):  
High Speed ◽  
Metal Vapor ◽  
Optical Systems ◽  
Imaging Method ◽  
High Speed Imaging ◽  
Destructive Testing ◽  
Copper Bromide ◽  
Imaging Results ◽  
High Pulse ◽  
Non Destructive

The imaging results of different processes blocked from the observation by the intense background light are presented in this paper. Active optical systems based on high-frequency brightness amplifier are used to decrease the negative factor of the glare. The experimental and modeling results on obtaining high pulse repetition frequencies (PRF) (more than 100 kHz) of copper bromide vapor brightness amplifiers operating in a low input energy mode are shown. The use of metal vapor brightness amplifiers for visual non-destructive testing of fast processes obscured by the glare is also discussed. It has been shown that the imaging method proposed in this paper proves to be the most reliable to obtain the information about objects or processes in a real time mode using high PRF CuBr active media.

Non-Destructive Detection of GIS Aluminum Alloy Shell Weld Based on Oblique Incidence Full Focus Method

2020 ◽  
Vol 1007 ◽  
pp. 105-110
Author(s):  
Xin Xin Wang ◽  
Cheng He ◽  
Pu Zhi Zhao ◽  
Yi Zheng ◽  
Shi Hao Jiang ◽  
...  
Keyword(s):  
Oblique Incidence ◽  
Near Field ◽  
Calibration Coefficient ◽  
Quantitative Detection ◽  
Imaging Method ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Field Range ◽  
Weld Defects ◽  
Non Destructive

In this paper, a new ultrasonic phased array full focus imaging method based on oblique incidence is proposed to solve the problem of the non-destructive testing of the internal defects in the GIS (gas insulated switchgear) shell welds. By using wedge coupling, the measured weld is far away from the near-field range of the transducer, and the detection angle range can be increased by changing the propagation direction of the acoustic beam. Based on Snell's law, the propagation characteristics of the ultrasonic wave in the interface are studied. On the basis of the conventional ultrasonic array matrix and the full focus imaging algorithm, by introducing the energy attenuation calibration coefficient of the acoustic wave propagation through the wedge, the correction amplitude of the specific focus point p(x, z) is obtained, The non-destructive testing of weld defects of GIS shell in the spot is carried out, and the test results show that the qualitative and quantitative detection of the weld defects can be well realized by using this method.

scholarly journals A Simple High-Resolution Near-Field Probe for Microwave Non-Destructive Test and Imaging

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2670
Author(s):  
Zipeng Xie ◽  
Yongjie Li ◽  
Liguo Sun ◽  
Wentao Wu ◽  
Rui Cao ◽  
...  
Keyword(s):  
High Resolution ◽  
Dielectric Material ◽  
Near Field ◽  
Skin Layer ◽  
Destructive Testing ◽  
Microwave Frequencies ◽  
Metal Materials ◽  
Microstrip Ring ◽  
Planar Circuit ◽  
Non Destructive

Non-destructive tests working at lower microwave frequencies have large advantages of dielectric material penetrability, lower equipment cost, and lower implementation complexity. However, the resolution will become worse as the work frequencies become lower. Relying on designing the structure of high field confinement, this study realizes a simple complementary spiral resonators (CSRs)-based near-field probe for microwave non-destructive testing (NDT) and imaging around 390 MHz (λ = 769 mm) whereby very high resolution (λ/308, 2.5 mm) is achieved. By applying an ingenious structure where a short microstrip is connected to a microstrip ring to feed the CSR, the probe, that is a single-port microwave planar circuit, does not need any extra matching circuits, which has more application potential in sensor arraying compared with other microwave probes. The variation of the electric field distribution with the standoff distance (SOD) between the material under test and the probe are analyzed to reveal the operation mechanisms behind the improved sensitivity and resolution of the proposed probe. Besides, the detection abilities of the tiny defects in metal and non-metal materials are demonstrated by the related experiments. The smallest detectable crack and via in the non-metal materials and the metal materials are of a λ/1538 (0.5 mm) width, a λ/513 (1.5 mm) diameter, a λ/3846 (0.2 mm) width and a λ/513 (1.5 mm) diameter, respectively. Moreover, to further evaluate the performance of the proposed probe, the defects under skin layer in the multilayer composite materials and the defects under corrosion in the carbon steel are inspected and imaged. Due to lower work frequency, high resolution, outstanding detection abilities of tiny defects, and large potentials in sensor arraying, the proposed probe would be a good candidate for microwave NDT and imaging.

Ultrasound Imaging Using Multilayer Synthetic Aperture Focusing

2010 ◽  
Author(s):  
Martin H. Skjelvareid ◽  
Yngve Birkelund
Keyword(s):  
Signal To Noise Ratio ◽  
Synthetic Aperture ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Wave Velocities ◽  
Homogenous Medium ◽  
Synthetic Aperture Focusing ◽  
Original Time ◽  
Non Destructive ◽  
Test Objects

Synthetic aperture focusing techniques (SAFT) have already been studied within several fields of non-destructive testing, but so far only with a single, relatively homogenous medium. In this article, we modify the original time-domain SAFT in order to image the interior of a multilayer structure. Standard focusing techniques assume that the wave velocity is constant within the volume to be imaged. The concept of the root-mean-square (RMS) velocity is used here to modify the classical delay-and-sum algorithm to handle layers with differing wave velocities. A scheme for iteratively using this to estimate the interfaces between the layers is also presented. The proposed method is demonstrated on ultrasonic B-scans of two test objects immersed in water, and it is shown that the increased lateral resolution and signal-to-noise ratio of standard SAFT is extended to the multilayer case. The increased resolution also makes it possible to accurately estimate the interfaces between consecutive layers, as long as the preceding interfaces are relatively smooth.

scholarly journals A Versatile Illumination System for Real-Time Terahertz Imaging

Sensors ◽  
2020 ◽  
Vol 20 (14) ◽  
pp. 3993
Author(s):  
Jean-Baptiste Perraud ◽  
Adrien Chopard ◽  
Jean-Paul Guillet ◽  
Pierre Gellie ◽  
Antoine Vuillot ◽  
...  
Keyword(s):  
Real Time ◽  
Signal To Noise Ratio ◽  
Beam Steering ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Full Field ◽  
Illumination System ◽  
Optimized Distribution ◽  
Non Destructive ◽  
Field Imaging

Terahertz technologies are attracting strong interest from high-end industrial fields, and particularly for non-destructive-testing purposes. Currently lacking compactness, integrability as well as adaptability for those implementations, the development and commercialisation of more efficient sources and detectors progressively ensure the transition toward applicative implementations, especially for real-time full-field imaging. In this work, a flexible illumination system, based on fast beam steering has been developed and characterized. Its primary goal is to suppress interferences induced by the coherence length of certain terahertz sources, spoiling terahertz images. The second goal is to ensure an enhanced signal-to-noise ratio on the detector side by the full use and optimized distribution of the available power. This system provides a homogeneous and adjustable illumination through a simplified setup to guarantee optimum real-time imaging capabilities, tailored to the sample under inspection. Working toward industrial implementations, different illumination process are conveniently assessed as a result of the versatility of this method.

scholarly journals The detection of flaws in austenitic welds using the decomposition of the time-reversal operator

2016 ◽  
Vol 472 (2188) ◽  
pp. 20150500 ◽  
Author(s):  
Laura J. Cunningham ◽  
Anthony J. Mulholland ◽  
Katherine M. M. Tant ◽  
Anthony Gachagan ◽  
Gerry Harvey ◽  
...  
Keyword(s):  
Time Reversal ◽  
Structural Integrity ◽  
Signal To Noise Ratio ◽  
Singular Values ◽  
Destructive Testing ◽  
Time Frequency ◽  
Frequency Domain Response ◽  
Value Decomposition ◽  
Imaging Algorithms ◽  
Non Destructive

The non-destructive testing of austenitic welds using ultrasound plays an important role in the assessment of the structural integrity of safety critical structures. The internal microstructure of these welds is highly scattering and can lead to the obscuration of defects when investigated by traditional imaging algorithms. This paper proposes an alternative objective method for the detection of flaws embedded in austenitic welds based on the singular value decomposition of the time-frequency domain response matrices. The distribution of the singular values is examined in the cases where a flaw exists and where there is no flaw present. A lower threshold on the singular values, specific to austenitic welds, is derived which, when exceeded, indicates the presence of a flaw. The detection criterion is successfully implemented on both synthetic and experimental data. The datasets arising from welds containing a flaw are further interrogated using the decomposition of the time-reversal operator (DORT) method and the total focusing method (TFM), and it is shown that images constructed via the DORT algorithm typically exhibit a higher signal-to-noise ratio than those constructed by the TFM algorithm.

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