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Open AccessProceedings ArticleDOI

Raw data based image processing algorithm for fast detection of surface breaking cracks

TLDR
In this paper, the authors illustrate the contribution of signal processing techniques in the field of non-destructive evaluation and demonstrate the capability of laser thermography for the detection of surface cracks and for the characterization of the geometry of artificial surface flaws.
Abstract
The aim of this work is to illustrate the contribution of signal processing techniques in the field of Non-Destructive Evaluation. A component’s life evaluation is inevitably related to the presence of flaws in it. The detection and characterization of cracks prior to damage is a technologically and economically significant task and is of very importance when it comes to safety-relevant measures. The Laser Thermography is the most effective and advanced thermography method for Non-Destructive Evaluation. High capability for the detection of surface cracks and for the characterization of the geometry of artificial surface flaws in metallic samples of laser thermography is particularly encouraging. This is one of the non-contacting, fast and real time detection method. The presence of a vertical surface breaking crack will disturb the thermal footprint. The data processing method plays vital role in fast detection of the surface and sub-surface cracks. Currently in laser thermographic inspection lacks a com...

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References
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Journal ArticleDOI

Ideal spatial adaptation by wavelet shrinkage

TL;DR: In this article, the authors developed a spatially adaptive method, RiskShrink, which works by shrinkage of empirical wavelet coefficients, and achieved a performance within a factor log 2 n of the ideal performance of piecewise polynomial and variable-knot spline methods.
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TL;DR: In this article, the decay of the wavelet transform amplitude across scales is investigated and it is shown that the local signal regularity is characterized by the decay in the amplitude of wavelets across scales.
Journal ArticleDOI

Crack imaging by scanning pulsed laser spot thermography

TL;DR: In this paper, a new crack imaging technique is presented that is based on second derivative image processing of thermal images of laser heated spots, which compare well with those obtained by the dye penetrant inspection method.
Journal ArticleDOI

Combined laser spot imaging thermography and ultrasonic measurements for crack detection

TL;DR: In this article, the authors used both cw and pulsed laser beam illumination on stainless steel and titanium samples and the technique was found to be successful for determining the location of fatigue cracks, where a surface crack, close to a small, well defined heated spot, impedes lateral heat flow and produces alterations in the shape of the thermal spot image that can be monitored by thermography.
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