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- 2018
- Phase difference method
- UTM
- Crack mouth opening displacement
- FBGs
- Three point bend specimens
- Prenotched concrete
- Plastic optical fiber
- Optoelectronic Information Science and Engineering
- National Institute of Technology, Warangal
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[IEEE 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Chongqing (2018.6.27-2018.6.29)] 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Methods for Long-Distance Crack Location and Detection of Concrete Bridge Structures
摘要： In order to improve the efficiency of crack detection of concrete bridge structures, a new method based on computer vision technology and coordinate mapping is proposed. In this research, this crack measurement system is integrated mainly with a high magnification image acquisition system, a two-dimensional electric cradle head device and a laser ranging system. It has a set of observing coordinate system. Firstly, the marking points’ image coordinates are mapped to the observation coordinates. Secondly, according to the marking points’ observation coordinates, the measured crack’s coordinates are mapped to a same world coordinates so as to realize the spatial location of the measured cracks regardless of different test cycles or instrument’s setup positions, which is a great convenience for the review detection of surface cracks of concrete bridge structures. The experiments show that this method is efficient and convenient. It can automatically locate the measured cracks within 16 s, and the deviation is not more than ± 0.07 °. At a distance of 100 m, the measurement accuracy of crack width is better than ± 0.12 mm.
关键词： long-distance,crack location,computer vision,spatial coordinate mapping,crack detection,concrete bridge structures
更新于2025-09-11 14:15:04
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In situ tailoring microstructure in laser solid formed titanium alloy for superior fatigue crack growth resistance
摘要： For damage tolerance (DT) titanium alloy, the fatigue crack growth resistance (FCGR) is a critical properties requirement for engineering applications. However, the Ti-6Al-4V-DT parts fabricated by laser solid forming (LSF) suffer from low FCGR, because of predominant basket-wave microstructure. Here, we have explored a novel LSF fabrication design to produce full colony microstructure, via in-situ controlled growth. The creation of such microstructures leads to superior FCGR, which markedly exceed conventional additive manufactured and mill-annealed samples. The present works provide a significant guidance for LSF-fabricated titanium alloy with high DT properties.
关键词： Titanium alloy,Fatigue crack growth resistance,Laser solid forming,Colony microstructure
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE International Conference on Image Processing (ICIP) - Taipei, Taiwan (2019.9.22-2019.9.25)] 2019 IEEE International Conference on Image Processing (ICIP) - Weakly Supervised Segmentation of Cracks on Solar Cells Using Normalized L <sub/>p</sub> Norm
摘要： Photovoltaic is one of the most important renewable energy sources for dealing with world-wide steadily increasing energy consumption. This raises the demand for fast and scalable automatic quality management during production and operation. However, the detection and segmentation of cracks on electroluminescence (EL) images of mono- or polycrystalline solar modules is a challenging task. In this work, we propose a weakly supervised learning strategy that only uses image-level annotations to obtain a method that is capable of segmenting cracks on EL images of solar cells. We use a modified ResNet-50 to derive a segmentation from network activation maps. We use defect classification as a surrogate task to train the network. To this end, we apply normalized Lp normalization to aggregate the activation maps into single scores for classification. In addition, we provide a study how different parameterizations of the normalized Lp layer affect the segmentation performance. This approach shows promising results for the given task. However, we think that the method has the potential to solve other weakly supervised segmentation problems as well.
关键词： solar cell,weakly supervised semantic segmentation,EL imaging,crack detection,normalized Lp norm
更新于2025-09-11 14:15:04
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Real-time observation of crack propagation and stress analysis during laser cutting of glass
摘要： Laser cutting of glass using a continuous-wave laser is attracting considerable attention because of its high processing speed and minimized generation of microcracks. During laser cutting of glass, a crack develops because of thermal stress and divides the glass plate. In this study, we observed crack propagation during laser cutting of glass in real time and found the distance between the crack tip and the laser irradiation position was 150 μm. Furthermore, we investigated the in?uence of the distance between the crack tip and the laser irradiation position on stress distribution and the stress condition necessary for crack growth. The results show the maximum principal stress at the crack tip increased as the distance between the crack tip and the laser irradiation position increased. In addition, we found that the crack developed when the maximum tensile stress of the crack tip reached 99 MPa. These results can be expected to enable the control of crack propagation and the estimation of appropriate processing conditions during laser cutting of glass.
关键词： laser,glass,cutting,finite element method,crack
更新于2025-09-11 14:15:04
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Effect of Different Forms of Application of a Laser Surface Treatment on Fatigue Crack Growth of an AA6013-T4 Aluminum Alloy
摘要： This work analyzes the effect of surface-localized laser heating treatment on the fatigue crack growth (FCG) rate on region II of the sigmoidal da/dN 3 DK curve of an aerospace-grade AA6013-T4 aluminum alloy sheet with 1.3 mm thickness. The in?uence on microstructure changes is also evaluated. Aiming to improve the FCG resistance without changing the mechanical behavior of the alloy, a Yb:?ber laser beam is defocused to generate a laser spot diameter of 2 mm, using 200 W power and a laser speed of 2 mm/s. Two laser lines are applied over fatigue C(T) specimens in two different forms: on only one and on both lateral specimen surfaces. Guinier–Preston zones, dispersoids and coarse constituent particles are found on the base material. On the heat-treated material, the same precipitates and also b￠ and Q￠ precipitates are found. These microstructural variations due to the laser thermal cycle, together with the presence of induced compressive residual stresses, improved the fatigue behavior of the material. The FCG retardation is optimized when two laser lines were applied on both lateral surfaces of the specimen.
关键词： aluminum alloy,microstructure,fatigue crack growth,residual stresses,laser surface treatment
更新于2025-09-11 14:15:04
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Estimation of Crack Mouth Opening Displacement in Concrete Using Optical Fiber Sensors
摘要： Concrete is a multi-phase composite material and used widely in construction industry because of high compressive strength and low cost. Its limited tensile strength makes it prone to cracking. Important parameters like characteristic length, fracture energy Gf critical crack width WC are used to understand cracks in concrete. The crack width is estimated either as crack mouth opening displacement (CMOD/COD) or as crack tip opening displacement (CTOD). Several optical and non-optical methods can provide information about crack presence but do not provide information on crack opening and crack width which are important from considerations of durability. To this end we present our research results in three point bend tests on pre-notched concrete samples (M-20 composition) using (a) Intensity based plastic optic fiber (POF) using phase difference measurement method (b) Fiber Bragg grating (FBG) method. The CMOD estimation and relative sensitivity of these methods will be presented.
关键词： Phase difference method,UTM,Crack mouth opening displacement,FBGs,Three point bend specimens,Prenotched concrete,Plastic optical fiber
更新于2025-09-11 14:15:04
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Nanoscratch on Single-layer MoS2 Crystal by Atomic Force Microscopy: Semi-circular to Periodical Zigzag Cracks
摘要： The fracture behaviors of single-layer molybdenum disulfide (MoS2) grown on SiO2/Si wafer by chemical vapor deposition (CVD) were systematically investigated here via a technique that combining AFM-based nanoscratch tests with friction force microscopy (FFM). To get a complete cognition of fracture behavior and deepen the understanding of mesoscopic anisotropy of the mechanical failure of 2D materials, the gradual process of fracture behavior on nanoscale layered films and confirmed the different fracture stages in the process, nanoscratch with progressive and constant force was done step by step. The radius of AFM tip we used is ~10 nm which is relatively blunt to produce a tensile fracture rather than pierce the film at the initial stage. As a result, there were novel crack modes with specific normal load in the surface of CVD-grown MoS2: semi-circular and periodical zigzag cracks, and both crack modes exhibit anisotropy during the generation and propagation.
关键词： nanoscratch,periodical zigzag crack,Single-layer,semi-circular crack,MoS2
更新于2025-09-10 09:29:36
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Handbook of Advanced Non-Destructive Evaluation || Induction Thermography of Surface Defects
摘要： A survey on theory, characteristic quantities, and the experimental technique of induction thermography is given. Induction thermography is used for surface defect detection in forged parts of ferromagnetic steel at typical frequencies of 100–300 kHz. Values for the detection limits for various types of cracks and approaches to determine crack depths are given. The sensitivity for crack detection is comparable to magnetic particle inspection. A hidden defect in ferritic steel with a coverage of 140 μm was detected by lowering the induction frequency down to 1500 Hz. Cracks in silicon solar cells were detected. Defects of ?bers were detected in carbon ?ber reinforced polymer (CFRP). Inductive excitation is complementary to ?ash excitation. Crack detection in railway components like rails and wheels was shown. In rails, a larger defect could be detected from a test car moving at a speed of up to 15 km/h. A fully automated demonstrator for wheel testing was built up, which can detect surface defects in railway wheels with sensitivity comparable to magnetic particle testing. Standardization of thermography has gained progress in the last years and led to ?rst standards on active thermography and induction thermography.
关键词： surface defect detection,induction thermography,crack detection,carbon fiber reinforced polymer,railway component testing,ferromagnetic steel
更新于2025-09-10 09:29:36
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[IEEE 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Chongqing (2018.6.27-2018.6.29)] 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Crack Detection and Images Inpainting Method for Thai Mural Painting Images
摘要： Thailand frescoes are an important art heritage in the world. However, the erosion of history has resulted in the color loss, stain and scratches of many mural paintings. How to repair the Thailand murals has become an urgent problem. It is an important scientific problem to use computer image inpainting technology to simulate and eliminate the missing pixels in the murals and obtain beautiful and intact murals. In this paper, a computer aided semi-automatic repair framework is proposed by combining a scratch detection procedure and a model optimization based inpainting procedure. To this end, we propose a scratch semi-automatic detection method. In this method, a small number of seed points are given by users, and the location of scratches is then computed by region growing method and morphological operation. After that, the pixel filling and color restoration in the missing region can be obtained by using different variational inpainting methods. The experiment shows that the proposed method is effective.
关键词： seed region growing,thai mural painting,images inpainting,images restroration,crack detection
更新于2025-09-10 09:29:36
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Bolted joint integrity monitoring with second harmonic generated by guided waves
摘要： In this study, the second harmonic generation due to the contact nonlinearity caused by bolt loosening is studied experimentally and numerically using three-dimensional explicit finite element simulations. In particular, it is demonstrated that the magnitude of the second harmonic generation normally increases with the loosening of the bolted joint, and there is a reasonable agreement between the numerical simulations and experimental results. The finite element model, which was validated against the experimentally measured data, is further utilized to investigate an important practical situation when a loosened bolt is weakened by fatigue cracks located at the edge of the hole. The numerical case studies show that the contact nonlinearity and the change of the behaviour of the second harmonic generation with the tightening level are very different to the corresponding results with the fatigue cracks. This identified difference in the second harmonic generation behaviour can serve as an indicator of the bolted joint integrity and thus provide early warning for engineers to make decision on the necessity of carrying out further safety inspections. Overall, the findings of this study provide improved physical insights into second harmonic generation for bolt loosening, which can be used to further advance damage detection techniques using nonlinear guided waves.
关键词： Bolt loosening,bolted joint,second harmonic generation,fatigue crack,contact nonlinearity,torque loss,structural health monitoring,guided waves
更新于2025-09-10 09:29:36