Temperature Dependence of Quiescent Currents as a Defect Prognosticator and Evaluation Tool

1996 ◽  
Author(s):  
J.S. Seo ◽  
S.S. Lee ◽  
S. Daniel ◽  
C.K. Yoon
Keyword(s):  
Spectrum Analysis ◽  
Theoretical Perspective ◽  
Temperature Curve ◽  
Photoemission Spectrum ◽  
Defect Characterization ◽  
Evaluation Tool ◽  
Actual Case ◽  
Valuable Complement ◽  
Current Characteristics ◽  
Non Destructive

Abstract The dependence of a defective device's voltage-current characteristics on temperature is studied, both from a theoretical perspective and through a series of actual case studies. The shape of the current vs. temperature curve is shown to be a good prognosticator of the defect type, and as such a valuable complement to other non-destructive defect characterization techniques such as photoemission spectrum analysis [1].

Non-destructive defect characterization of concrete structures reinforced by means of FRP

2007 ◽  
Vol 49 (3) ◽  
pp. 218-223 ◽  
Author(s):  
U. Galietti ◽  
V. Luprano ◽  
S. Nenna ◽  
L. Spagnolo ◽  
A. Tundo
Keyword(s):  
Concrete Structures ◽  
Defect Characterization ◽  
Non Destructive

scholarly journals 3D Internal Visualization of Concrete Structure Using Multifaceted Data for Ultrasonic Array Pulse-Echo Tomography

Sensors ◽  
2021 ◽  
Vol 21 (19) ◽  
pp. 6681
Author(s):  
Hungjoo Kwon ◽  
Changbin Joh ◽  
Won Jong Chin
Keyword(s):  
Evaluation Method ◽  
Ultrasonic Pulse ◽  
Evaluation Tool ◽  
Limited Budget ◽  
Pulse Peak ◽  
Synthetic Aperture Focusing ◽  
Synthetic Aperture Focusing Technique ◽  
Pulse Echo ◽  
Structure Evaluation ◽  
Non Destructive

This research proposes a 3D internal visualization using ultrasonic pulse-echo tomography technique to evaluate accurately the state of concrete structures for their efficient maintenance within a limited budget. Synthetic aperture focusing technique (SAFT) is used as a post-processing algorithm to manipulate the data measured by the ultrasonic pulse-echo technique. Multifaceted measurements improve the weakness of the existing ultrasonic pulse-echo tomography technique that cannot identify the area beyond a reflector as well as the area located far away from measuring surfaces. The application of apodization factor, pulse peak delay calibration and elimination of trivial response not only complements the weaknesses of the SAFT algorithm but also improves the accuracy of the SAFT algorithm. The results show that the proposed method reduces the unnecessary surface noise and improves the expressiveness of the reflector’s boundaries on the resulting images. It is expected that the proposed 3D internal visualization technique will provide a useful non-destructive evaluation tool in combination with another structure evaluation method.

Non-Destructive Evaluation of the Degradation of Ni-Base Superalloy in the Air by Reflectance Spectrum Analysis

2020 ◽  
Author(s):  
Shin Kasama ◽  
Ken Suzuki ◽  
Hideo Miura
Keyword(s):  
Power Generation ◽  
Plastic Deformation ◽  
Spectrum Analysis ◽  
Reflectance Spectrum ◽  
Thermal Power ◽  
Renewable Energies ◽  
Fatigue Load ◽  
Creep Fatigue ◽  
Non Destructive ◽  
Base Superalloy

Abstract Thermal power generation is required to be highly efficient due to concerns such as environment and energy problems. In order to improve its efficiency, it is thermodynamically essential to increase operating temperature. In addition, since thermal power generation is expected to control its output to be coexistent with renewable energies of which output varies frequently depending on weather, not only simple fatigue or creep load but also creep-fatigue load is applied to its component because it is required to assure the safe and stable energy supply under random output of the renewable energies. Since the effective lifetime of heat-resistant alloys decreases drastically under creep-fatigue load, however, it is very important to develop a non-destructive inspection method which can detect the degradation of the crystallinity of the alloys such as local plastic deformation, local oxidation, and local change of micro texture (segregation/precipitation). In this research, the reflectance spectrum analysis of the component elements was applied to the observation of the change in the local crystallinity of Ni-base superalloy (Alloy 617). A creep-fatigue test was applied to a small specimen, and the change of the local reflectance spectrum was measured under the irradiation of a white light. It was confirmed that the change of the surface roughness in the damaged area caused by plastic deformation and the growth of the surface oxide were successfully observed by the spectrum analysis. In addition, the distribution of fine carbides and nitrides was visualized by the spectrum analysis. It was also confirmed that a thick Cr-rich oxide layer grew at the grain boundaries only in the heavily damaged area. Finally, it was concluded that the creep-fatigue damage was clearly visualized by the spectrum analysis.

Quantitative ultrasonics

1979 ◽  
Vol 292 (1390) ◽  
pp. 233-250 ◽  
Keyword(s):  
Fracture Mechanics ◽  
Sufficient Information ◽  
Defect Characterization ◽  
Science Center ◽  
Destructive Testing ◽  
Test Procedures ◽  
Ultrasonic Scattering ◽  
Ultrasonic Measurements ◽  
Recent Developments ◽  
Non Destructive

Ultrasonic non-destructive testing, as currently used in industry, is limited by its non-quantitative capabilities. In this sense, non-quantitative means that current technology is capable only of producing a signal that indicates the presence of a flaw, but it is unable to say anything about the characteristics of the flaw, e.g. its size, shape, orientation, and the m aterial of which it is composed (void or inclusion). This lim itation has been brought into sharp focus in recent years with the advent of fracture mechanics as a m ajor structural design and m aintenance philosophy. Since fracture mechanics is quantitative in nature, its effective utilization as an accept/reject criterion for flaws in materials and structures thus requires that quantitative inform ation be available from the non-destructive test procedures used to assure the design. W ith this lim itation in mind, the Defense Advanced Research Projects Agency (Darpa) and the Air Force M aterials Laboratory (A.F.M .L.) jointly initiated work at the Science Center, Rockwell International, to explore and to improve this situation. The work is structured to include both Science Center and university participants, and includes research and development in several areas necessary to achieve a quantitative capability. These areas include transducers, acoustic imaging, and defect characterization. In this paper principal emphasis is placed upon the defect characterization work that has been done. The approach that has been used is that of ultrasonic scattering, an approach which recognizes that several measurements must be taken at different angles and frequencies in order to acquire sufficient information to characterize a flaw. Items that are discussed include the design and preparation of a set of flawed samples in which the flaws are well characterized, theoretical developments that describe the ultrasonic scattering interaction with these flaws, experimental verification of these models, and inversion processes that have been developed to process the data and deduce flaw parameters from the ultrasonic measurements. A comparison of the deduced flaw param eters with the initially known values is given. Two other topics are discussed. One of these concerns recent developments in the analysis of long wavelength scattering which suggest that it should be possible to obtain stress intensity factors from ultrasonic measurements. The second item is concerned with recent developments in non-contact transducers (electromagnetic acoustic transducers (e.m.a.ts)) that are particularly related to weld inspection.

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