Near field synthetic aperture ultrasonic imaging: non-destructive testing

1992 ◽  
Author(s):  
S.D. Silverstein ◽  
L.J. Thomas
Keyword(s):  
Near Field ◽  
Ultrasonic Imaging ◽  
Synthetic Aperture ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Non Destructive

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.

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 OPTO-TECHNICAL MONITORING – A STANDARDIZED METHODOLOGY TO ASSESS THE TREATMENT OF HISTORICAL STONE SURFACES

2018 ◽  
Vol XLII-2 ◽  
pp. 945-952
Author(s):  
M. Rahrig ◽  
R. Drewello ◽  
A. Lazzeri
Keyword(s):  
Near Field ◽  
Three Dimensional ◽  
Non Destructive Testing ◽  
New Materials ◽  
Testing Methods ◽  
Destructive Testing ◽  
Monitoring Method ◽  
Horizon 2020 ◽  
Research And Innovation ◽  
Non Destructive

Monitoring is an essential requirement for the planning, assessment and evaluation of conservation measures. It should be based on a standardized and reproducible observation of the historical surface. For many areas and materials suitable methods for long-term monitoring already exist. But hardly any non-destructive testing methods have been used to test new materials for conservation of damaged stone surfaces. The Nano-Cathedral project, funded by the European Union's Horizon 2020 research and innovation program, is developing new materials and technologies for preserving damaged stone surfaces of built heritage. The prototypes developed are adjusted to the needs and problems of a total of six major cultural monuments in Europe. In addition to the testing of the materials under controlled laboratory conditions, the products have been applied to trial areas on the original stone surfaces. For a location-independent standardized assessment of surface changes of the entire trial areas a monitoring method based on opto-technical, non-contact and non-destructive testing methods has been developed. This method involves a three-dimensional measurement of the surface topography using Structured-Light-Scanning and the analysis of the surfaces in different light ranges using high resolution VIS photography, as well as UV-A-fluorescence photography and reflected near-field IR photography.<br> The paper will show the workflow of this methodology, including a detailed description of the equipment used data processing and the advantages for monitoring highly valuable stone surfaces. Alongside the theoretical discussion, the results of two measuring campaigns on trial areas of the Nano-Cathedral project will be shown.

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