Case Studies in Nondestructive Testing and Evaluation

Characterization of planar flaws by non-destructive evaluation is crucial from the point of view of structural integrity assessment. An approach involving SAFT processing of B-scan image collected by electronic scanning using linear array has been used for detection and characterization of planar flaws. The study was carried out on stainless steel plate with slots inclined at various orientations and carbon steel plates having implanted weld planar flaws. The results of these investigations are presented in this paper.

Paritosh Nanekar

Anish Kumar

T. Jayakumar

Characterization of planar flaws by synthetic focusing of sound beam using linear arrays

利用线性阵列合成聚焦声束表征平面缺陷

Joule heating losses in the working coil of up to 50% make thermal loads a crucial influencing factor on the coil lifetime in electromagnetic forming processes. Thus, especially in case of discharge sequences with short cycle times knowledge about the temperature distribution is essential to avoid thermal overstressing. This paper presents an approach for temperature measurement inside the working coil during the electromagnetic forming process. Based on fiber-based optical frequency domain reflectometry (OFDR), the spatio-temporal temperature distribution inside the coil is determined. Temperature profiles for long-term discharge sequences are provided. The results prove the qualification of this measurement technique for electromagnetic forming processes. Due to the comparatively high acquisition rate the temperature increase and drop between two discharges can be analyzed in detail. This renders new possibilities for process analysis and monitoring. Especially the effectiveness of approaches aiming at a decrease of thermal loading can be rated easily using the presented measurement technique.

S. Gies

A. Langolf

C. Weddeling

A.E. Tekkaya

Measurement of working coil temperature in electromagnetic forming processes by means of optical frequency domain reflectometry

通过光学频域反射测量电磁成形过程中工作线圈温度的测量

This case study demonstrates the type of non-destructive analysis possible using X-ray micro computed tomography (microCT) for a titanium aerospace investment casting of 225 mm in its longest axis. The advantages of the method are highlighted while the limitations are also discussed. Recently the method has become more accessible and affordable due to multi-user service facilities and the analysis has become simpler due to software and hardware improvements. This case study demonstrates a typical analysis including defect detection, wall thickness and part to CAD comparison, which can be done in less than 4 h, while simpler results are possible in under 1 h. This will be particularly useful for industries requiring quick but detailed non-destructive analysis.

Anton du Plessis

Pierre Rossouw

X-ray computed tomography of a titanium aerospace investment casting

钛合金航空航天熔模铸件的X射线计算机断层扫描

Air void content is one of the most important characteristics of in-place asphalt concrete, substantially affecting early deterioration and long term performance. Destructive measures at limited locations, such as coring, are typically conducted as part of the air-void content evaluation after the pavement has been fully constructed. In this paper, use of an air coupled step-frequency array system for nondestructive assessment of air-void variability is explored. The dielectric properties of the asphalt were determined from the asphalt surface reflection amplitude of all 21 adjacent transmitting and receiving pairs of the array and related to air void content through plotting of dielectric changes with core measured air void content. This approach is an extension of the procedure developed for a single bistatic antenna pair determining properties within top millimeters of the asphalt surface. While cores provide information concerning bulk properties across the depth, the proposed method with an array system provides an opportunity for increased lateral coverage. The case study demonstrated good repeatability and correspondence with core measured air void content. The array-based method improves the coverage and productivity of the measurements, making it an attractive alternative to current state-of-the-practice procedures.

Kyle Hoegh

Lev Khazanovich

Shongtao Dai

Thomas Yu

Evaluating asphalt concrete air void variation via GPR antenna array data

通过GPR天线阵列数据评估沥青混凝土空隙变化

X-ray scatter dark field imaging (SDFI) tomography was used to investigate the glass fibre orientation of short fibre-reinforced polymers (SFRPs). The fibre orientation of fibre-reinforced polymers is decisive for the mechanical strength of injection-moulded parts. For this paper four different positions, with volumes along the melt flow and with weld lines, of an injection-moulded part were investigated with SDFI computed tomography with a voxel size of (43 μm)3 and absorption-based high resolution X-ray computed tomography (XCT) with a voxel size of (6.5 μm)3. The results of the SDFI computed tomography are compared with the fibre orientation to investigate the dependence of the SDFI signal on fibre orientation. The exact fibre orientation was determined by evaluation of the high resolution absorption XCT data. In particular, it is shown that the weld line and areas with different fibre orientations can be characterised by SDFI even at a voxel size of (43 μm)3 and that fibre orientation properties can be detected.

Christian Hannesschläger

Vincent Revol

Bernhard Plank

Dietmar Salaberger

Johann Kastner

Fibre structure characterisation of injection moulded short fibre-reinforced polymers by X-ray scatter dark field tomography

通过X射线散射暗场断层扫描技术对注塑成型短纤维增强聚合物的纤维结构表征

Abstract This paper describes the development of different novel antenna concepts for improving the spatial resolution of microwave based non-destructive testing (NDT) at 24 GHz. In a great number of applications the antenna of the sensor can be brought very close to the device under test. In these cases, the near field characteristics of the antennas are crucial for a high resolution. However, common sensor heads offer either a high image resolution or a high penetration depth. In order to combine both of the characteristics different antenna concepts have been developed. The objectives were to obtain a high return loss combined with a sufficient high dynamic range and a near field focusing of electromagnetic waves in order to yield a high resolution. Altogether, three antennas have been set up. Each antenna has been calculated analytically, followed by a FEM simulation, near field measurements and an experimental verification.

Christian Ziehm

Sebastian Hantscher

Johann Hinken

Christian Ziep

Maik Richter

Near field focusing for nondestructive microwave testing at 24 GHz – Theory and experimental verification

24 GHz下无损微波检测的近场聚焦——理论与实验验证

In this paper, we present the results of a failure analysis done on new heat exchanger tubes, which shows loss of thickness during a EC inspection to stablish a prior loss of thickness base line aiming guarantee fitness for service during its working life. The root cause analysis indicates that there is intergranular corrosion due a differential concentration caused by seawater evaporation inside the tubes during the ship transit from the port of origin in China to the destination port in Brazil. The intergranular corrosion depth showed by root cause failure analysis is smaller than that showed by EC inspection. We attribute the EC inspection results deviation to a tube magnetisation due to mechanical stress and to a secondary phase due to an incomplete solubilisation after tube conforming and welding. Traditionally, these tubes are visually inspected and deemed acceptable but our conclusions reveal that eddy current testing is capable of detecting some corrosion anomalies which makes the tubes unfit for service.

J.D. Angelo

A. Bennecer

P. Picton

S. Kaczmarczyk

A. Soares

Eddy current analysis of shipped stainless steel heat exchanger bundle

运输不锈钢换热器束的涡流分析

This paper discusses vibration serviceability assessment of a highly trafficked local footbridge based on the experimental tests and analytical studies. The selected bridge is an approximately 60 m (196 ft) long multi-span steel structure with a continuous reinforced concrete slab supported on two longitudinal steel girders. The experimental study consists of ambient vibration and pedestrian interaction tests to describe the dynamic characteristics of the selected bridge structure. The fundamental frequency of the bridge in the vertical direction obtained through ambient vibration tests was within the critical range described by available design guidelines. This required further analysis to assess the performance of the bridge relative to the maximum acceleration thresholds. In addition to the peak dynamic response obtained from the pedestrian interaction tests, peak acceleration values were calculated analytically based on current design guidelines and compared to the comfort limits. Results from both experimental and analytical studies suggest that the footbridge possesses satisfactory serviceability performance under low and dense traffic conditions, but the comfort level under very dense traffic loads was classified as minimum according to the results of the analytical calculations.

Amir Gheitasi

Osman E. Ozbulut

Salman Usmani

Mohamad Alipour

Devin K. Harris

Experimental and analytical vibration serviceability assessment of an in-service footbridge

在役人行桥的振动适用性试验与分析评估

This study evaluates the necessity of considering Transmitter–Receiver (T–R) offset distance for predicting pavement layer thicknesses from two-way travel time data captured by a Ground Penetrating Radar (GPR) antenna. For the purpose of this study, GPR testing was conducted at an instrumented pavement section at Milepost (MP) 141 on Interstate I-40 near Albuquerque, New Mexico, USA. The GPR system used for this study consists of 2.0 GHz air-launched, 900 MHz ground-coupled, and 400 MHz ground-coupled antennas. The entire instrumented test section was tested with different antenna configurations. The two-way travel time is used for calculating layer thicknesses using two approaches: one considering the T–R offset, which is a non-conventional approach and the other without considering the T–R offset, which is a conventional approach. Statistical analysis namely, t-test is performed on the predicted layer thicknesses from these two approaches. The analysis indicates that these two approaches are significantly different. The predicted thicknesses by these two approaches are compared to each other. It is observed that the approach considering the T–R offset predicts the layer thicknesses with better accuracy compared to the conventional approach. Therefore, it is recommended to use the T–R offset in predicting pavement layer thickness from GPR data.

M.U. Ahmed

R.A. Tarefder

A.K. Maji

Incorporating transmitter–receiver offset to interpret pavement layer thicknesses by GPR

结合发射器-接收器偏移解释路面层厚度的探地雷达方法

Stephan Gerhard le Roux

Anina Guelpa

Comparison of medical and industrial X-ray computed tomography for non-destructive testing

医学与工业X射线计算机断层扫描在无损检测中的比较

Publication Information	Publisher: Elsevier B.V.，Publishing cycle: ，Journal Type: journal，Open Access Journals: No
Basic data	Year of publication: 2014，Proportion of original research papers: ，Self Citation Rate:， Gold OA Rate:

Case Studies in Nondestructive Testing and Evaluation

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