Enhanced air-coupled impact echo technique by phase analysis of signals from multiple sensors

This paper presents an air-coupled impact echo(IE)technique that relies on the phase spectrum of the collected data to find the frequencies corresponding to the reflections from delaminations.The proposed technique takes advantage of the fact that the IE compression wave is not a propagating wave,but it is the 1st order symmetrical(S1)mode Lamb wave at zero group velocity(S1-ZGV).Therefore,it searches the phase spectra of the data collected by multiple sensors to locate the frequency corresponding to the lowest phase difference.As a result,the technique reduces the effect of propagating waves,including the direct acoustic wave and ambient noise.It is named the Constant Phase IE(CPIE).The performance of the CPIE is experimentally compared with the regular amplitude spectrum-based IE technique and two other multisensor IE techniques.The CPIE shows a performance advantage,especially in a noisy environment.

Application of ultrasonic inspection in monitoring dynamic healing of mandibular fracture in rabbit model

Objective:To investigate the feasibility of ultrasonic diagnosis for monitoring fracture healing. Methods:Thirty rabbit models with fraction of mandible body were established by surgically removing partial lower jawbone.At the 1st,2nd,4th,6th,8th and 12th week after the operation, they were examined by X-ray and ultrasound,respectively.All detection results were scored according to a generally accepted standard.Spearman rank correlation analysis was conducted to explore the relationship between the results of the two inspection methods.Results:In each healing stage,the results of the ultrasonic inspection were basically consistent with those of the X-ray examination,as supported by a Spearman rank correlation coefficient of 0.892(P【0.001). Conclusions:Non-invasive ultrasonic inspection can be used instead of X-ray examination to monitor and diagnose fracture healing.

Study of ultrasonic phased array inspection imaging technology for NDT

A research about the ultrasonic phased array imaging principle from A-scan signal to B-scan image for non-destructive testing （NDT） was conducted in this paper, the ultrasonic phased array inspection imaging system used in industrial field was developed and the experiment was performed on the steel testing block by the system with 64 elements, 5 MHz phased array transducer. Experimental results show that the flaws could be accurately detected and the flaws size could be estimated from the B-scan images, and the B-scan images could clearly show the location of the flaws, but the quality of B-scan images needs to be enhanced by digital signal processing and controlling dynamic focusing for improving the image resolution.

High Precision Ultrasonic Guided Wave Technique for Inspection of Power Transmission Line

Due to the merits of high inspection speed and long detecting distance, Ultrasonic Guided Wave（UGW） method has been commonly applied to the on-line maintenance of power transmission line. However, the guided wave propagation in this structure is very complicated, leading to the unfavorable defect localization accuracy. Aiming at this situation, a high precision UGW technique for inspection of local surface defect in power transmission line is proposed. The technique is realized by adopting a novel segmental piezoelectric ring transducer and transducer mounting scheme, combining with the comprehensive characterization of wave propagation and circumferential defect positioning with multiple piezoelectric elements. Firstly, the propagation path of guided waves in the multi-wires of transmission line under the proposed technique condition is investigated experimentally. Next, the wave velocities are calculated by dispersion curves and experiment test respectively, and from comparing of the two results, the guided wave mode propagated in transmission line is confirmed to be F（1,1） mode. Finally, the axial and circumferential positioning of local defective wires in transmission line are both achieved, by using multiple piezoelectric elements to surround the stands and send elastic waves into every single wire. The proposed research can play a role of guiding the development of highly effective UGW method and detecting system for multi-wire transmission line.

Laser ultrasonic testing for near-surface defects inspection of 316L stainless steel fabricated by laser powder bed fusion

The laser powder bed fusion(L-PBF)method of additive manufacturing(AM)is increasingly used in various industrial manufacturing fields due to its high material utilization and design freedom of parts.However,the parts produced by L-PBF usually contain such defects as crack and porosity because of the technological characteristics of L-PBF,which affect the quality of the product.Laser ultrasonic testing(LUT)is a potential technology for on-line testing of the L-PBF process.It is a non-contact and non-destructive approach based on signals from abundant waveforms with a wide frequency-band.In this study,a method of LUT for on-line inspection of L-PBF process was proposed,and a system of LUT was established approaching the actual environment of on-line detection to evaluate the method applicability for defects detection of L-PBF parts.The detection results of near-surface defects in L-PBF 316L stainless steel parts show that the crack-type defects with a sub-millimeter level within 0.5 mm depth can be identified,and accordingly,the positions and dimensions information can be acquired.The results were verified by X-ray computed tomography,which indicates that the present method exhibits great potential for on-line inspection of AM processes.

Localization of a Robotic Capsule for GI Motility Inspection with a Portable Ultrasonic System

The micro-systems used for in vivo physical inspection have many advantages over traditional methods. In order to aid diagnosis of gastrointestinal (GI) motility disorders, a capsule is developed for GI pressure and pH inspection. Localization of the capsule in GI tract with time is a necessary condition for subsequent data analysis and medical diagnosis. It is also a common problem facing all in vivo mobile micro-systems. An approach of segment localization by utilizing some key points along GI tract is proposed. A portable ultrasonic detecting device was designed for this purpose. Experiments under conditions similar to GI tract were carried out and the results proved the effectiveness and reliability of this method and the device.

Ultrasonic inspection for circumferential butt joint of austenitic stainless steel with carbon steel

Tthe practical application of ultrasonic wave inspection in welded joint by austenitic stainless steel with carbon steel is presented. It is shown from the experimental results that the high frequency narrow-pulsed longitudinal ultrasonic wave inspection technique can detect the defects in deferent sound path and location within the tested welded joint clearly and exactly. The study in the paper may provide a new approach for further application of ultrasonic inspection in coarse-grained materials.

Evaluation of thermal sprayed coating using ultrasonic inspection by means of bottom echo back reflection

Thermal spraying technique is widely used in various mechanical parts as a surface reforming technique.However,as demand to maintain superior mechanical performance in harsh operating environment increases,the need for non-destructive evaluation method for thermal spray coating becomes more important.For this purpose,we thinned the thickness of the thermal sprayed coating by abrasion with blasting and used ultrasonic inspection by means of bottom echo reflection for effective measurement of abrasion quantity in thermal sprayed coating.The results obtained are summarized as follows.When the thickness of thermal sprayed coating becomes thin,the echo height increases.This is because thermal sprayed coatings absorb ultrasonic energy.Ultrasonic energy absorbed by Al2O3 is smaller compared with Fe-13Cr coating.Thermal sprayed coatings submerged in water have a lower echo height compared with air.As mentioned above,the thermal sprayed coating thickness can be estimated using ultrasonic inspection by means of bottom echo back reflection.

Inspection system for welded tubular joint based on ultrasonic phased array

A manual inspection of large-diameter tubular joints is difficult. As a result a scanner with three degrees of freedom （ DOFs） was developed based on the scanning principle of ultrasonic phased array. The weld tracing is realized by a 2DOF motion of scanner. The pose of ultrasonic probe is controlled by the third one. The control strategy is put forward based on a programmable multi-axis controller. Four kinds of scanning modes can be implemented simultaneously employing this ultrasonic inspection system. Experiments on reference blocks of tubular joints reveal that the automatic ultrasonic phased array inspection system has the same inspection accuracy as a manual ultrasonic inspection. This system is superior to the manual ultrasonic system in terms of reliability and repeatability. The artificial dejects of weld at tubular joint can be detected accurately with the presented inspection system.

Weld seam recognition algorithm based on HSI space for pipeline ultrasonic flaw inspection

In order to realize automatic weld seam tracking for pipeline ultrasonic flaw inspection, an image processing algorithm based on HSI color space was presented. Since the color tones of weld seam were different from the parent metal, weld seam images were transformed to HSI color space. In the HSl colar space, the weld seam and base metal area can be apparently distinguished. By using this image processing algorithm, the edges and centerline of pipeline weld seam can be correctly extracted. An industrial application system was developed based on the image processing algorithm, and the image processing time is less than 70 ms and the accuracy of weld seam recognition is better than 2mm.

On the possible ultrasonic inspection of micro-bubbles generated by the optical fiber tip

We demonstrate the possibility of detection and monitoring of bubbles emerging near the tip of an optical fiber by means of ultrasonic method.The excitation of bubbles at their resonant frequencies is performed using short ultrasonic pulses having a wide frequency range simulta-neously with their modulation by means of a long pulse of a monochromatic frequency.This method allows detection of bubbles of various sizes.Used signal processing method,which allows increased bubble detection accuracy,is proposed for ressearch in envir onments of biological-like medium which show continuous variations in structure and properties when exposed to optical emission.The method has been demonstrated on model objects:in a liquid and in a biological tissue phantom using various methods of bubble generation(hydrolysis and optical enission).We studied bubble formation by the tip of a fiber of the surgical laser LSP-007/10 "IRE Polus"with a wavelength of 0.97μm coated with a highly absorbing graphite layer.

Non-Contact Velocity Measurement of Japanese Cedar Columns Using Air-Coupled Ultrasonics

The ultrasonic wave velocities of Japanese cedar columns were measured using a non-contact method. An air-coupled ultrasonic wave was propagated through the axial and lateral directions of wood. The velocities in the axial direction (VL) showed the minimum values around the pith. The averaged VL increased from 3600 m/s towards the outside of measurement area and attained the maximum values (=4010 m/s). The velocities in the lateral direction (VRT ) showed no tendency among measurement points. The averaged VRT was 1450 m/s. The velocities obtained using the non-contact method showed a significant positive relationship with those obtained using the contact method. The averaged ratio of VL to VRT was measured to be approximately 2.2 to 2.8. These ratios were in agreement with those from a contact method. These findings suggest that it is possible to measure the velocity in Japanese cedar columns with the non-contact method by using air-coupled ultrasonics.

Applications of Ultrasonic Techniques in Oil and Gas Pipeline Industries: A Review

The diversity of ultrasound techniques used in oil and gas pipeline plants provides us with a wealth of information on how to exploit this technology when combined with other techniques, in order to improve the quality of analysis. The fundamental theory of ultrasonic nondestructive evaluation (NDE) technology is offered, along with practical limitations as related to two factors (wave types and transducers). The focus is limited to the two main techniques used in pipe plants: First, straight beam evaluation and second, angle beam evaluation. The depth of defect (DD) is calculated using straight beam ultrasonic in six different materials according to their relative longitudinal wave (LW) velocities. The materials and respective velocities of LW are: rolled aluminum (6420 m/s), mild steel (5960 m/s), stainless steel-347 (5790 m/s), rolled copper (5010 m/s), annealed copper (4760 m/s), and brass (4700 m/s). In each material eight defects are modeled;the first represents l00% of the material thickness (D), 50.8 mm. The other seven cases represent the DD, as 87.5% of the material thickness, 75%, 62.5%, 50%, 37.5%, 25%, and 12.5%, respectively. Using angle beam evaluation, several parameters are calculated for six different reflection angles (βR) (45°, 50°, 55°, 60°, 65° and 70°). The surface distance (SD), ½skip distance (SKD), full SKD, and 1½SKD,½sound path (SP) length, full SP, and 1½SP are calculated for each βR. The relationship of SKD and SP to the βR is graphed. A chief limitation is noted that ultrasound testing is heavily dependent on the expertise of the operator, and because the reading of the outcome is subjective, precision may be hard to achieve. This review also clarifies and discusses the options used in solving the industrial engineering problem, with a comprehensive historical summary of the information available in the literature. Merging various NDE inspection techniques into the testing of objects is discussed. Eventually, it is hoped to find a suitable technique combined with ultrasonic inspection to deliver highly effective remote testing.

Development of ZZC-1 ultrasonic testing system for centre bores of turbine rotors

General Great importance is being attached in the electric power in-dustry to the inspection of rotor shafts. This is because defects areusually concentrated at the central part of large forgings for makingrotors, some remnants of them may still remain after the centre borehas been drilled. Some rotors even have quite a number of defects atlocations rather remote from the centre bore. Working conditions for steam turbine rotors are very ex-

The Ultrasonic NDT Technique Utilizing the Longitudinal or Transverse Waves Induced by Lamb Wave in Thin Plates

This paper presents a new ultrasonic NDT technique for measuring the thicknessof a nonmetal material(called the ciadding material)with low sound velocity which iscladded on the one side of a thin metal plate(called the base)with high sound velocity such as tubes,tins and other closed containers,testing and inspecting the unglued area betweenthem,detecting the inner defect of the compesite from the side of the base in case that themeasurement and inspection has to be carried out on the side of the base.The principle ofthe technique is that a longitudinal or transverse wave induced by the pulse Lamb wave inthe base is transmited in certam direction into the compounded material,then reflected bythe upper and lower boundary of the compounded material.The same mode pulse Lambwave is formed while the longitudinal or transverse wave in the compounded material returnthe base.

"Smart" ultrasonic pig design and its signal processing research

This paper introduces the design and development of intelligent ultrasonic ＂pig＂ used for seabed pipeline inspection. The data acquisition system （DAS） and the signal processing method are presented. The DAS was designed using a muhi-DSP based structure. The signal processing method adopted a well-enhanced split-spectrum processing （SSP） based on weighting algorithm according to statistical times, which was the statistical distribution of the discrete signals selected by the minimization algorithm. Furthermore, the data compressing method was discussed. It assures the mass data to be processed and compressed in real-time. The effectiveness of the method was proved by laboratory experiments. The research provides an excellent base for further development of the ultrasonic pig.

Flaw Detection Capability and Sensitivity in the Inspection of Nuclear Containment Liner and Shell Mock-Ups Utilizing a Magnetostrictive Sensor (MsS) Guided Wave UT Technique

This paper describes the results of a project on the inspection of visually inaccessible areas of nuclear containment liners and shells via the advanced Magnetostrictive sensor (MsS) Guided Wave (GW) nondestructive inspection technique. Full scale mockups that simulated shell and liner regions of interest in the containment of both a Pressurized Water Reactor (PWR) and Boiling Water Reactor (BWR) were constructed. Inspections were performed on the mock-ups in three stages to discern the signal attenuation caused by flaws and caused by concrete in the structures. The effect of concrete being in close proximity to the liner and shell was determined, and the capability to detect and size flaws via this GW technique was evaluated.

Development of Automatic Phased Array Inspection System for Long-distance Pipeline

In the paper the development of phased array technique home and abroad is summarized, the overall structure and main research on phased array inspection system are introduced,and meanwhile the future field of study and development of phased array ultrasonic inspection technique is pointed out.

燃料组件破损棒自动超声检查系统关键技术研究

燃料组件长期服役过程中,会因为振动、材料老化、强辐照等原因发生破损,这为核电机组安全运行带来隐患,而燃料组件破损自动超声检测系统尚未达到完全国产化。为此,该文从检测理论、探头和采集系统方面讨论了自动超声检测系统中的关键技术,同时对声束传播过程和响应进行了仿真和试验验证。试验结果表明,实际测量结果与理论模型吻合,自主研制的自动超声检查系统可有效分辨燃料组件破损棒。

核电厂安全壳贯穿件焊缝自动超声检测系统开发

通过分析国内某核电厂贯穿件焊缝现场检查条件,阐述国内外现有管道检测装置的不适应性,本文提出了一种管道贯穿件对接全焊透环焊缝自动超声检测的技术方案,解决了该焊缝手动检查不可达的问题,实现了贯穿件管道狭窄空间内检测装置的快速安装和定位,操作简单、高效。采用开发的检测系统应用于某核电厂贯穿件焊缝在役检查,结果表明检测系统满足现场检查要求,验证了技术开发的有效性。