scholarly journals Noncontact Laser Ultrasound Detection of Cracks Using Hydrophone

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3371
Author(s):  
Ki-Chang Kang ◽  
Kwan-Kyu Park
Keyword(s):  
Ultrasonic Method ◽  
Ultrasonic Inspection ◽  
Contrast Ratio ◽  
Pulsed Laser ◽  
Image Contrast ◽  
Laser Ultrasound ◽  
Impedance Mismatch ◽  
Inspection Method ◽  
Ultrasound Signal ◽  
Immersion Type

We present a noncontact, non-immersion ultrasonic inspection method. A broadband ultrasound signal generated by a pulsed laser was measured using a hydrophone. The generated ultrasound signals propagated through the specimen and received a signal from the hydrophone in the water. Soldered chip ceramic capacitors, resistors, and surface-mount-type chip amplifiers were used as experimental specimens. A polydimethylsiloxane layer was used to prevent the specimen from being impacted by contact with water. The presence of a crack in the middle of the specimen resulted in an air layer, and the intermediate air layer reduced the magnitude of the signal transmitted owing to impedance mismatch. Using this principle, the cracks in each specimen could be distinguished. The image contrast ratio derived from the proposed method is approximately two to three times higher than that derived using the conventional immersion ultrasonic method. These results show that the proposed method can replace existing immersion-type ultrasound transmitted images.

A Practical Ultrasonic Inspection Method for Detecting and Characterising Defects Found Within Composite Repairs

2018 ◽  
Author(s):  
J Downing ◽  
A Hook
Keyword(s):  
Wall Thickness ◽  
Steel Substrate ◽  
Ultrasonic Method ◽  
Ultrasonic Inspection ◽  
Heat Exposure ◽  
Matrix Cracking ◽  
Ultrasonic Technique ◽  
Inspection Method ◽  
Composite Repairs ◽  
Layered Matrix

Two steel substrate test panels were developed to represent common plate thicknesses found on naval vessels and scanned using the Babcock developed ultrasonic technique. One sample comprised of a series of slotted surface breaking flaws of varying widths and through thicknesses to represent fracturing/cracking. The inspection method detected simulated cracking to a depth of 2mm and 0.5mm in width. The second sample included numerous loss of wall thickness areas of varying diameters and through thicknesses, with the smallest detectable loss of wall thickness being 0.1mm at a 15mm diameter. After proving confidence in detection, there was a need to characterise flaws to provide support and ascertain a repair action. Samples were produced that were subjected to either impact or heat exposure to induce realistic representative damage. The practical ultrasonic method was successfully used to independently characterise between the samples, with induced de-laminations caused by blisters, and multi layered matrix cracking caused by varying levels of projectile impacts, due to their unique morphology.

Pulsed-Laser Ultrasound Generation in Graphite/Epoxy Plate

2000 ◽  
Vol 12 (1) ◽  
pp. 191-215 ◽  
Author(s):  
A. Rezaizadeh ◽  
J. C. Duke
Keyword(s):  
Pulsed Laser ◽  
Laser Ultrasound

A Real-Time Approach To Detect Seal Defects in Food Packages Using Ultrasonic Imaging

2001 ◽  
Vol 64 (9) ◽  
pp. 1392-1398 ◽  
Author(s):  
NEIL N. SHAH ◽  
PAUL K. ROONEY ◽  
AYHAN OZGULER ◽  
SCOTT A. MORRIS ◽  
WILLIAM D. O'BRIEN
Keyword(s):  
Image Quality ◽  
Ultrasonic Inspection ◽  
Spatial Sampling ◽  
Ultrasonic Frequency ◽  
Ultrasound Images ◽  
Inspection Method ◽  
Raster Scanning ◽  
Food Packages ◽  
Inspection Systems ◽  
Scanning Geometry

The microbial integrity of many types of flexible food packages depends on a zero defect level in the fused seam seal. Human inspection for defects in these seals is marginal at best, and secondary incubation protocols are often used to spot packages with compromised integrity before releasing product for sale. A new type of inspection method has been developed and is being evaluated for robustness. The purpose of the study was to evaluate a new raster scanning geometry to simulate continuous motion, online ultrasonic inspection of the seal region in flexible food package seals. A principal engineering tradeoff of scanning inspection systems is between increased line speed that results from decreased spatial sampling (less acquired data to process) and decreased image quality. The previously developed pulse-echo Backscattered Amplitude Integral (BAI) mode imaging technique is used to form ultrasound images using the new scanning geometry. At an ultrasonic frequency of 22.9 MHz, 38- and 50-μm-diameter air-filled channel defects in all-plastic transparent trilaminate are evaluated. The contrast-to-noise ratio (CNR) of the processed BAI-mode image is used to quantify image quality as a function of spatial sampling. Results show seal defects (38- and 50-μm diameter) are still detectable for undersampled conditions, although image quality degrades as spatial sampling decreases. Further, it is concluded that the raster scanning geometry is feasible for online inspection.

Automatic Ultrasonic Inspection Method of Railway Axle and its Remaining Life Prediction

2011 ◽  
Vol 213 ◽  
pp. 291-296 ◽  
Author(s):  
Hong Wei Hu ◽  
Xiong Bing Li ◽  
Xiang Hong Wang ◽  
Yi Min Shao
Keyword(s):  
High Speed ◽  
Fatigue Cracks ◽  
Ultrasonic Inspection ◽  
Inspection System ◽  
Remaining Life ◽  
High Speed Railway ◽  
Inspection Method ◽  
Spiral Trajectory ◽  
Image Element ◽  
The Matrix

With the high speed railway utilization, the probability of defects or fatigue cracks in railway axles is increased. An automatic ultrasonic inspection system for railway axles is presented. This system uses combined probes and inspects the defects with spiral trajectory along the axis of the axle. Through the matrix representation of C-scan image element, a defect edge extraction method is adopted, with which the defect parameters of crack are obtained automatically. Based on these defect parameters, the stress intensity factor is assessed by svm regression and the method to predict remaining life is proposed.

Ultrasonic Inspection of Thin Duplex Steel Welds by Phased Array

2015 ◽  
Vol 818 ◽  
pp. 256-259
Author(s):  
Erika Hodúlová ◽  
Ingrid Kovaříková ◽  
Beáta Šimeková ◽  
Koloman Ulrich
Keyword(s):  
Weld Joint ◽  
Phased Array ◽  
Ultrasonic Inspection ◽  
Base Material ◽  
Outer Diameter ◽  
Experimental Sample ◽  
Inspection Method ◽  
Duplex Steel ◽  
Steel Welds ◽  
Weld Root

The non-destructive inspection of duplex steels is a big challenge, being composed of ferrite and austenite, have some particularities. When using ultrasound, for instance, its waves propagate well in ferrite, but suffer strong attenuation, scattering and refraction in austenite. The aim of this work is to use the Phased Array ultrasonic inspection method for the thin (4 mm) duplex steel weld joint inspection. The experimental sample was made ​​of duplex steel shaped tube with an outer diameter of 44 mm and a wall thickness of 3.8 mm welded with a laser beam. The experiment was necessary to verify attenuation of duplex steel. On the base material and the weld joint were made the artificial defects, in which the adjusted sensitivity of the ultrasonic device was set.The result of the measuring was the defect echo coming from the weld root layer. The length (about 25 mm) can only be estimated due to the inaccurate constant velocity of probe motion along the surface.

Measurement of Welding Residual Stress by Ultrasonic Technology

2015 ◽  
Vol 750 ◽  
pp. 206-213 ◽  
Author(s):  
Hu Chen ◽  
Jin Dan Zhu ◽  
Yan Xun Xiang
Keyword(s):  
Residual Stress ◽  
Ultrasonic Method ◽  
Ultrasonic Inspection ◽  
Welding Residual Stress ◽  
Ultrasonic Technology ◽  
Longitudinal Residual Stress ◽  
Measurement Results ◽  
Acoustic Elasticity ◽  
Good Repeatability ◽  
Acoustic Travel Time

An ultrasonic method was developed to measure the residual stress in a welded joint based on the modified acoustic-elasticity theory. Phase frequency analysis method was introduced by incombination with shear wave and longitudinal wave. The acoustic-elasticity parameters of joint material was derived by ultrasonic inspection during loading experiment. Transverse and longitudinal residual stress was determined by precisely measuring of short-distance acoustic travel time. The ultrasonic measurement results was confirmed by H&K theory and XRD methods with good repeatability and reliability.

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