Nondestructive Inspection System Research Articles

?Nondestructive Inspection System Using Optical Profiles and Laser Surface Waves to Detect a Surface Crack

?Nondestructive Inspection System Using Optical Profiles and Laser Surface Waves to Detect a Surface Crack

Spectral line-scan imaging system for high-speed non-destructive wholesomeness inspection of broilers

A spectral line-scan imaging system was developed for automated online wholesomeness inspection of broilers and evaluated in a commercial chicken processing plant. Real-time online hyperspectral images acquired by the system on a 140 bird-per-minute processing line were analyzed to optimize Region of Interest (ROI) size and location and to determine key wavebands by which to implement online high-speed multispectral inspection. Multispectral imaging algorithms were implemented to automatically recognize individual carcasses entering and exiting the field of view, to locate the ROI on the bird, and to determine the condition for each carcass as being wholesome or unwholesome. The high accuracy obtained from the in-plant evaluation results showed that the system can effectively perform food safety inspection tasks on high-speed processing lines. The system is being adapted for commercial use in pre-sorting chicken during initial processing operations, to help poultry processors improve production efficiency and satisfy increasing consumer demand for poultry products.

エリアアレイ型フリップチップ実装構造 : バンプ接続部状態の非破壊検査システム(<小特集>電子機器の熱・機械信頼性と機械工学)

エリアアレイ型フリップチップ実装構造 : バンプ接続部状態の非破壊検査システム(<小特集>電子機器の熱・機械信頼性と機械工学)

Imaging and Metrology of Silicon Carbide Wafers by Laser-Based Optical Surface Inspection System

There is a great need for an in-line, high-speed and non-destructive inspection system capable of evaluating and analyzing the quality of SiC wafers for SiC power devices. We have examined whether the laser-based optical non-destructive inspection system by KLA-Tencor meets these requirements. Using this system, incoming inspection of purchased SiC wafers has been performed. The obtained inspection data show that micropipe density is sufficiently low in a device-grade wafer, and therefore, micropipes are not the main cause of device failure. The next challenges for a device-grade SiC wafer are reduction of epitaxial defects and relatively small defects classified as “particles”.

LASER ULTRASONIC INSPECTION SYSTEM WITH A 3D SURFACE PROFILOMETRY TO DETECT SURFACE CRACKS

We have developed a nondestructive surface-crack detection system by using laser ultrasound and optical 3D surface profilometry. The system can robustly acquire crack information by using the laser ultrasonic analysis data with visual surface profiling data where both data are produced by the same line-shaped pulse laser beam. By the help of the visual 3D shape data for a surface crack, this ultrasonic inspection system can provide reliable surface crack information. In this paper, the hardware configuration of the combined nondestructive laser inspection system to detect surface cracks will be described. Also, the experimental results to detect multi surface cracks by using the developed system will be presented.

Development of Eddy Current Testing System for Complicated-Shaped Components

The objectives of this study are to develop a new inspection probe for complex structures using eddy current testing method (ECT), to establish the recognition technique of real flaw shape such as stress corrosion cracking (SCC), and to develop a rapid nondestructive inspection system. An ECT system consists of measurement and computational modules that are connected via a network circuit. The measurement module includes a flexible ECT sensor, which could fit on the curvature surface of radius larger than 25 mm with a mechanical manipulator. The computational module is used for SCC sizing. It includes a database of ECT signals that are used to execute numerical calculations. SCC sizing can be evaluated by comparing the measured ECT signals with the calculated ECT signals within the database. We have demonstrated that the system could be used to estimate the SCC length and depth sizing in 140 s. The accuracy of length sizing showed an RMS error of 3.7 mm and the depth sizing was 0.63 mm in this work.

Evaluation of the quality of commercial silicon carbide wafers by an optical non-destructive inspection technique

There is a great need for an in-line, high-speed and non-destructive inspection system capable of evaluating and analyzing the quality SiC wafers for SiC power devices. We have examined whether the laser-based optical non-destructive inspection system by KLA-Tencor meets these requirements. By optimizing the optical setup and improving the defect recognition and classification recipe, we have successfully mapped classified defects on a SiC wafer. Using this system, incoming inspection of purchased SiC wafers has been performed. The obtained inspection data show that micropipe density is sufficiently low in a device-grade wafer and, therefore, micropipes are not the main cause of device failure. The next challenges for a device-grade SiC wafer are reduction of epitaxial defects and relatively small defects classified as “particles”.

Overhead line wooden pole condition sensing by acoustic method

The paper presents the design of a sensing system for non-destructive inspection of the health condition of wooden poles for overhead power lines. Acoustic impulse responses are collected for the analysis of the condition of different wooden poles. The concept of cumulative energy spectrum for feature extraction is introduced. Fuzzy logic is also used to solve the problem of small samples. Experimental results and the accuracy of the method are also presented.

Evaluation of Adhesive Strength in the Bonded Area of Shoes by Using IR Camera

The Infrared Camera usually detects only Infrared waves emitted from the light in order to illustrate the temperature distribution. An Infrared diagnosis system can be applied to various fields. But the defect discrimination can be automatic or mechanized in the shoes total inspection system. The thermal images of the specimens were analyzed. In shoes, weak bonding due to the separation of the bonded parts delamination causes defects. The most serious defect occurs in the bonding between the outer covering of the shoe and the sole, and to up now, this defect has been detected only by inspection with the naked eye. This study introduces a method for special shoes nondestructive total inspection. Performance of the proposed method is shown through thermo-Image. In search of superior inspection methods, we evaluated an applicable non-destructive inspection method and also carried out basic research for developing an innovative nondestructive inspection system for shoes. The total inspection system using infrared thermal camera for special shoes, its applicability, and system configuration are introduced.

Non-destructive inspection using HTS–SQUID on aluminum liner covered by CFRP

An eddy-current-based SQUID non-destructive inspection (NDI) system to detect deep-lying cracks in multi-layer composite-Al vessels was developed taking advantage of the uncontested sensitivity of HTS–SQUID in low-frequency range. An HTS–SQUID gradiometer was mounted in a pulse tube cryocooler. A pair of differential coils with C-shaped ferrite cores was employed to induce an enhanced eddy current in an Al vessel wrapped in a carbon fiber reinforced plastic (CFRP) cover. Ellipsoidal dome-shaped Al liners containing through cracks, which were made by pressure cycle tests, in the CFRP covers with total thickness of 6mm (CFPR 3mm, and Al 3mm) were inspected by the system. While inducing eddy currents in the vessels with excitation fields at 100Hz or 7kHz, the vessels were rotated under the HTS–SQUID. Above the cracks, anomalous signals due to the cracks were clearly detected at both frequencies. These results suggested the SQUID-NDI technique would be a possible candidate for inspection of high-pressure multi-layer composite-Al vessels.

Tailoring of magnetic imaging system for nondestructive inspection

A previously developed robotic 3D superconducting quantum interference device (SQUID) imaging system, i.e., one that is not stationary but rather the SQUID sensor itself moves or scans along the surface of the object, was improved. A new sharp dewar tail design allows the SQUID sensor itself scans in 3D by travelling over the free-form surface areas of an object during testing without the need for magnetic shielding. The magnetic flux resolution was slightly better than that of the previous system when SQUID sensor was mounted on an insulating material, sapphire instead of copper.

Nondestructive inspection system for corrosion detection in fuel tank liners

An ultrasonic, nondestructive inspection system for the early detection of corrosion in fuel tank aluminum liners was developed and tested. A Labview‐controlled scanner, which rode on the tank’s resident rib braces, housed a 10‐MHz transducer and a miniature video camera. The bi‐directional (axial, azimuthal) scan resolution was controlled by adjusting the surface standoff distance of the focused transducer to produce variable‐area interrogation sites. The phenomenon of increased backscatter from corrosion‐roughened surfaces was exploited to detect the presence of corrosion in its early stages. The transducer acted as both transmitter and receiver, capturing the echoes from the subject surface while the video camera captured an image of the surface under acoustic inspection. The acoustic and visual data were overlayed to form a composite image of the entire inspection surface. The system was field‐tested using two tanks pulled from active duty at the Marine Corps maintenance facility in Cherry Point, NC. [Work supported by JCAA.]

Numerical simulation on magnetic flux leakage evaluation at high speed

High-speed non-destructive inspection (NDI) systems using magnetic flux leakage method (MFL) is in great demand in online metal inspection and defect characterisation, especially in pipeline and rail track inspection. For MFL systems at high speed measurement, in addition to magnetic flux, eddy currents exist in metal specimen because of the relative movement between the probe and specimen. These currents alter the profile of electromagnetic field, which increases difficulty in signal interpretation and defect characterization. In this paper, eddy currents generated by high speed movement and their characterisation in high-speed MFL inspection systems were investigated by using numerical simulations. Besides, the MFL signals from high speed MFL measurement against defect depth were examined.

Modeling of Characteristics of Magneto-Optical Sensor Using FEM and Dipole Model for Nondestructive Evaluation

The magneto-optical nondestructive inspection system (hereafter refer to as RMO system) using magneto-optical sensor (hereafter refer to as MO sensor) offers the benefits of providing image data and LMF information at the same time. Therefore this system makes it possible to carry out remote and high speed inspection of cracks from the intensity of the reflected light and to estimate the shape of a crack more effectively than by already existing methods. In other words, the shape of crack could be evaluated using image data, and crack depth can be determined by calculating the intensity of reflected light. The purposes of this study were to confirm the vertical components of leakage magnetic flux from a crack using RMO system and to verify the effects of MO sensor using the finite element method and dipole model calculation. The effectiveness of these analysis methods was compared with experiments using a RMO system and several types and sizes of the crack on plate specimens. The volume of a crack could be estimated using the optical intensity regardless of the shape of cracks.

Development of a Nondestructive Inspection System for Detection of Illicit Drugs Hidden in Envelopes

Development of a Nondestructive Inspection System for Detection of Illicit Drugs Hidden in Envelopes

Evaluation of heat seal quality of aseptic food containers by ultrasonic and optical microscopic imaging

Non-destructive testing by the ultrasonic imaging method was evaluated to determine the heat seal quality of aseptically produced semi rigid cups, sealed at temperatures ranging from 150 to 200 °C. Non-contact ultrasonic testing in pulse/echo mode using high frequency sound waves generated by a 20 MHz ultrasonic transducer was used to evaluate heat-seal quality. In order to relate ultrasonic response with the actual seal condition, various seal regions of a semi rigid container were sectioned for optical microscopic imaging and seal characterization. Results showed that ultrasonic signals could reflect the effects of the sealing process on the seal integrity. Change in the ultrasonic signals indicated an insufficient or non-uniform heat seal at sealing temperatures of 150–170 °C, resulting in weak seals or discontinuities. Short seal width was observed at all sealing temperatures, indicating unparallel alignment of the sealing tool. Optical imaging correlated well with ultrasonic imaging. However, uniformity of heat seal did not correlate well with the magnitude of the ultrasonic signal, possibly due to non-uniform surfaces of heat seals. These results suggest that this non-destructive ultrasonic inspection system detects the quality of heat seals, which can eliminate potential failures and improve process control.

同軸型パルスチューブ冷凍機を用いた低磁気ノイズＳＱＵＩＤ非破壊検査システムの開発

A small, low-magnetic-noise nondestructive inspection (NDI) system that uses a high-Tc superconducting quantum interference device (SQUID) cooled by a coaxial pulse tube cryocooler (PTC) has been developed. The key components for realizing the compact, low-noise system developed in this study, include the following: a high-Tc SQUID gradiometer, the coaxial PTC, and a SQUID-mount stage separated from the cold head of the cryocooler. The high-Tc SQUID gradiometer contributes not only to stable system operation when subjected to the environmental noise without magnetic shielding, but also a decrease in magnetic noise caused by the mechanical vibration of the SQUID, which is transmitted from the cryocooler. By using the coaxial PTC, which was constructed of non-magnetic materials, both magnetic noise and the mechanical vibration are well suppressed compared to conventional two-axial PTCs. In addition, the coaxial PTC is designed to be compact (50 mm diameter, 400 mm height, and 4 kg weight) for practical use. The SQUID-mount stage separation contributes to stable operation by reducing the transmitted vibration to the SQUID, and thermal stability at the SQUID-mount stage. The magnetic flux noise spectrum of the cryo-cooled system was measured and compared with that of a liquid-nitrogen-cooled system using the same SQUID. From the comparison, no increase in magnetic noise due to the cryocooler was observed, although the magnetic flux noise level of the cryo-cooled system was dominated by SQUID operation noise, which was rather high, (i.e., around 100 μΦ0/Hz1/2 at 100 Hz). The relation between the mechanical vibration at the SQUID and magnetic noise is discussed.

System for Nondestructive Inspection of Large Objects in Machine Engineering

A nondestructive inspection system based on two new linear accelerators UELV-15-2D-100 with nominal energy 15 MeV and bremsstrahlung dose rate up to 120 Gy/min 1 m from the target has been developed and built. This system will be used for transillumination of thick objects using the radiographic and introscopic methods. Combining two systems – radiographic and introscopic – into a single system has made it possible to obtain results much more quickly. Fourth-generation accelerators have yielded unique results at 1-1T ASTM resolution in a wide range of object thicknesses.

Application of a NDI method using magneto-optical film for micro-cracks

Leakage magnetic flux is occurred in the cracked area of magnetized specimens, and also it changes the magnetic domain area of the magneto-optical film positioned on the specimen. It causes the change of the optical permeability of the magnetic domain on the crack area. So crack images can be obtained easily using this principle. On the other hand, utilizing a laser in this method makes possible to perform a remote sensing by detecting the light intensity contrast between cracked area and normal area. This paper shows the application of non-destructive inspection system taking advantage of magneto-optical method for micro-cracks and presents examples applied to the several types of specimens having fatigue cracks and fabricated cracks using this method. Also the authors prove the possibility of this method as a remote sensing system under the oscillation load considering application to real fields.

Hybrid laser/broadband EMAT ultrasonic system for characterizing cracks in metals

Detection and characterization of defects in metal parts in industrial and commercial settings has typically been carried out by nondestructive ultrasonic inspection systems. Correct measurement of crack size is critical for lifetime prediction inspections. Normally, measurements are made based on far-field ultrasonic diffraction models and time-of-flight reflection signals making accurate measurements for parts less than approximately 25 mm in thickness impossible. In this work a hybrid noncontacting laser generation/broadband electromagnetic acoustic transducer (EMAT) detection system is used to characterize ideal cracks in aluminum in which the far-field condition for ultrasonic diffraction cannot be met. Time domain signals show that diffracted energy is measured in the geometrical shadow zone of the crack. Fourier transform methods are used to show that the frequency content of the diffracted signals is different than those from the waves that do not interact with the crack. Crack size measurements are made by using the frequency content of the ultrasonic signal rather than time-of-flight information.