Influence of absorptivity of the material surface in crack detection using laser spot thermography

Puthiyaveettil, Nithin; Rajagopal, Prabhu; Balasubramaniam, Krishnan

doi:10.1016/j.ndteint.2021.102438

Cited by 16 publications

(5 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Point A is the detection result of the algorithm in this paper, with the spot center position of (256.006,295.998), point B is the detection result of Hough transform, the coordinate of the center point is (258.4,298.9), and point C is the detection result of barycenter method, which is (259.6,307.3). It is not difficult to see from the detection results that the error between the spot center and the ideal center obtained by this algorithm is much less than 0.1 pixel, which is obviously higher than the other two algorithms and has high accuracy [5][6].…”

Section: Artificial Spot Analysismentioning

confidence: 87%

“…Where: a1k+a2 is a fitted straight line equation; Ye is the detection result of spot center in y direction of each algorithm; K=1,2,3,4,5 represents the collected five light spots, and the detection results of various algorithms in each stroke are fitted according to the least square principle. Because the high-precision electric translation stage is used in the experiment and the images used in each analysis are the same group, the error of the detection results is mainly introduced by the algorithm, and the reliability (accuracy) of each fitted line can be measured by equation (5).…”

Section: Figure1 Experimental System Block Diagrammentioning

confidence: 99%

See 1 more Smart Citation

High-precision detection of laser spot based on Gaussian spot model

Liang,

Wang

2023

5th International Conference on Information Science, Electrical, and Automation Engineering (ISEAE 2023)

View full text Add to dashboard Cite

In order to understand the application of laser spot high precision detection, a laser spot high precision detection based on Gaussian spot model was proposed. Laser spot center location is one of the key techniques in optical measurement. Firstly, by analyzing the common positioning algorithms, this paper presents a Gaussian fitting method using the unsaturation point in the spot image and taking the amplitude point of the fitting function as the center of the spot. Secondly, artificial light spot is used to verify the algorithm. The results show that the error of the algorithm is much less than 0.1 pixel, and it is a feasible spot center location algorithm.

show abstract

Section: Artificial Spot Analysismentioning

confidence: 87%

Section: Figure1 Experimental System Block Diagrammentioning

confidence: 99%

High-precision detection of laser spot based on Gaussian spot model

Liang,

Wang

2023

5th International Conference on Information Science, Electrical, and Automation Engineering (ISEAE 2023)

View full text Add to dashboard Cite

show abstract

“…Titanium alloy material has the minimum thermal conductivity 𝜆, the diffusion rate of thermal wave is slow, and the amplitude of surface temperature rise and thermal gradient caused by heat source excitation is the largest, but the heat affected zone is small, so it is necessary to reduce the scan line spacing to ensure the integrity of defect detection. Due to the similar thermal diffusivity of nickel-based and iron-based alloys [35], the characteristics of temperature change field of the two materials are similar under circular Gaussian heat source excitation, and the difference in crack detection is small [36].…”

Section: Thermodynamic Properties Of Materialsmentioning

confidence: 99%

Nondestructive Surface Crack Detection of Laser-Repaired Components by Laser Scanning Thermography

et al. 2022

View full text Add to dashboard Cite

As a revolutionary new technique, laser-engineered net shaping (LENS) is a layer additive manufacturing process that enables accurate, rapid and automatic repair of industrial component damage. In the laser repair (LR) process or in service, surface cracks can appear, which have a detrimental effect on the repair quality and the mechanical performance; therefore, the surface crack detection of repaired components has attracted much attention. Laser spot thermography is an important nondestructive testing method with the advantages of non-contact, full-field and high precision, which shows great potential in the crack detection of repaired components. The selection of thermographic process parameters and the optimization of thermal image processing algorithms are key to the success of the nondestructive detection. In this paper, the influence of material properties and thermographic process parameters on the surface temperature gradient is studied based on the simulation of laser spot thermal excitation, and the selection windows of thermographic process parameters for iron-based and nickel-based alloys are obtained, which is applied to the surface crack detection of repaired components. To improve the computational efficiency of thermal images, the Prewitt edge detection algorithm is used in the thermal image processing, which realized fast extraction of cracks with a high signal-to-noise ratio (SNR), and the detection sensitivity of crack width can reach 10 μm. To further study the influence of surface roughness on the thermographic detection, repair layers with and without polishing process are characterized, which show that the Prewitt edge detection algorithm is well applicable to crack detection on surfaces with different roughness level.

show abstract

“…The segmented image can be used for analysis and to detect damage, but algorithms have to be used to remove the noise from the images. Puthiyaveettil et al [12] used laser spot thermography to detect surface crack in metals. The laser is used to excite the surface under inspection.…”

Section: Introductionmentioning

confidence: 99%