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Detection for transverse corner cracks of steel plates’ surface using wavelet

Qiong ZHOU, Qi AN

《机械工程前沿（英文）》 2009年 第4卷 第2期   页码 224-227 doi: 10.1007/s11465-009-0017-x

摘要： An algorithm is presented for detecting transverse corner cracks at a steel plate surface using wavelet transform. According to characteristics of transverse corner crack images, the wavelet transform is used for the multi-scale analysis of detecting the image edges and disintegrating the image into four directions at the same time. The proper threshold value is chosen to segment the image into vertical components to obtain the final detection result. The experiment shows that transverse corner cracks of steel plates can be more effectively extracted by the proposed method than the other two common methods.

关键词： transverse corner cracks     defect detection     multi-scales wavelet analysis    

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P60钢轨鱼鳞伤萌生寿命

石嵘,范志毅,何越磊

《中国工程科学》 2008年 第10卷 第8期   页码 65-68

摘要：

上海轨道交通1号线锦江乐园至莘庄路段P60钢轨使用至今已出现不同程度伤损。曲线路段的部分钢轨外轨内侧出现鱼鳞伤，严重的鱼鳞伤甚至向下发展导致核伤。鱼鳞伤在疲劳裂纹的初期发展缓慢，随着疲劳荷载次数增加，裂纹深度扩展速率dh/dN发生转折。定义裂纹深度扩展速率发生转折时对应的疲劳荷载的次数为鱼鳞伤萌生寿命。

关键词： 钢轨     鱼鳞伤     疲劳裂纹     裂纹深度扩展速率     萌生寿命    

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Microbial self-healing of cracks in cement-based materials and its influencing factors

《结构与土木工程前沿（英文）》 doi: 10.1007/s11709-023-0986-6

摘要： Cement-based materials are brittle and crack easily under natural conditions. Cracks can reduce service life because the transport of harmful substances can cause corrosion damage to the structures. This review discusses the feasibility of using microbial self-healing agents for crack healing. Tubular and spherical carriers can be used to load microbial self-healing agents and protect microbes, which prolongs the self-healing time. The area self-healing ratio, permeability, mechanical strength, precipitation depth method, numerical modeling, and ultrasonic method can be employed to identify the self-healing effect of cracks. Moreover, the self-healing mechanism is systematically analyzed. The results showed that microbial self-healing agents can repair cracks in cement-based materials in underground projects and dam gates. The difficulties and future development of self-healing cracks were analyzed. A microbial self-healing agent was embedded in the cement-based material, which automatically repaired the developing cracks. With the development of intelligent building materials, self-healing cracks have become the focus of attention.

关键词： cement-based materials     cracks     microbial self-healing agent     mechanism     intelligent building materials    

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Shadow obstacle model for realistic corner-turning behavior in crowd simulation

Gao-qi HE,Yi JIN,Qi CHEN,Zhen LIU,Wen-hui YUE,Xing-jian LU

《信息与电子工程前沿（英文）》 2016年 第17卷 第3期   页码 200-211 doi: 10.1631/FITEE.1500253

摘要： This paper describes a novel model known as the shadow obstacle model to generate a realistic corner-turning behavior in crowd simulation. The motivation for this model comes from the observation that people tend to choose a safer route rather than a shorter one when turning a corner. To calculate a safer route, an optimization method is proposed to generate the corner-turning rule that maximizes the viewing range for the agents. By combining psychological and physical forces together, a full crowd simulation framework is established to provide a more realistic crowd simulation. We demonstrate that our model produces a more realistic corner-turning behavior by comparison with real data obtained from the experiments. Finally, we perform parameter analysis to show the believability of our model through a series of experiments.

关键词： Corner-turning behavior     Crowd simulation     Safety awareness     Rule-based model    

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Effect of axial load and transverse reinforcements on the seismic performance of reinforced concrete

Mounir Ait BELKACEM, Hakim BECHTOULA, Nouredine BOURAHLA, Adel Ait BELKACEM

《结构与土木工程前沿（英文）》 2019年 第13卷 第4期   页码 831-851 doi: 10.1007/s11709-018-0513-3

摘要： The aim of this research is to assess the seismic performance of reinforced concrete columns under different axial load and transverse reinforcement ratios. These two parameters are very important as for the ductility, strength, stiffness, and energy dissipation capacity for a given reinforced concrete column. Effects of variable axial load ratio and transverse reinforcement ratio on the seismic performance of reinforced concrete columns are thoroughly analyzed. The finite element computer program Seismo-Structure was used to perform the analysis of series of reinforced concrete columns tested by the second author and other researchers. In order to reflect the reality and grasp the actual behavior of the specimens, special attention was paid to select the models for concrete, confined concrete, and steel components. Good agreements were obtained between the experimental and the analytical results either for the lateral force-drift relationships or for the damage progress prediction at different stages of the loading.

关键词： reinforced concrete columns     axial load     transverse reinforcement     ductility    

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Fatigue crack growth simulations of 3-D linear elastic cracks under thermal load by XFEM

Himanshu PATHAK,Akhilendra SINGH,I.V. SINGH,S. K. YADAV

《结构与土木工程前沿（英文）》 2015年 第9卷 第4期   页码 359-382 doi: 10.1007/s11709-015-0304-z

摘要： This paper deals with the fatigue crack growth simulations of three-dimensional linear elastic cracks by XFEM under cyclic thermal load. Both temperature and displacement approximations are extrinsically enriched by Heaviside and crack front enrichment functions. Crack growth is modelled by successive linear extensions, and the end points of these linear extensions are joined by cubic spline segments to obtain a modified crack front. Different crack geometries such as planer, non-planer and arbitrary spline shape cracks are simulated under thermal shock, adiabatic and isothermal loads to reveal the sturdiness and versatility of the XFEM approach.

关键词： 3-D cracks     fatigue life     Paris law     thermal load     XFEM    

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Investigation of Generalized SIFs of cracks in 3D piezoelectric media under various crack-face conditions

Jaroon RUNGAMORNRAT, Bounsana CHANSAVANG, Weeraporn PHONGTINNABOOT, Chung Nguyen VAN

《结构与土木工程前沿（英文）》 2020年 第14卷 第2期   页码 280-298 doi: 10.1007/s11709-019-0586-7

摘要： This paper investigates the influence of crack geometry, crack-face and loading conditions, and the permittivity of a medium inside the crack gap on intensity factors of planar and non-planar cracks in linear piezoelectric media. A weakly singular boundary integral equation method together with the near-front approximation is adopted to accurately determine the intensity factors. Obtained results indicate that the non-flat crack surface, the electric field, and the permittivity of a medium inside the crack gap play a crucial role on the behavior of intensity factors. The mode-I stress intensity factors ( ) for two representative non-planar cracks under different crack-face conditions are found significantly different and they possess both upper and lower bounds. In addition, for impermeable and semi-permeable non-planar cracks treated depends strongly on the electric field whereas those of impermeable, permeable, and semi-permeable penny-shaped cracks are identical and independent of the electric field. The stress/electric intensity factors predicted by permeable and energetically consistent models are, respectively, independent of and dependent on the electric field for the penny-shaped crack and the two representative non-planar cracks. Also, the permittivity of a medium inside the crack gap strongly affects the intensity factors for all crack configurations considered except for of the semi-permeable penny-shaped crack.

关键词： crack-face conditions     intensity factors     non-flat cracks     permittivity     piezoelectric media     SGBEM    

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墙角火灾环境下钢构件温度分布及响应行为的实验研究

陈长坤,姚斌,杨昀,蔡昕,张和平,万玉田

《中国工程科学》 2005年 第7卷 第9期   页码 70-75

摘要：

利用ISO9705标准火灾实验系统，模拟墙角火灾环境，以薄壁方管钢梁为研究对象，对钢构件在热、力耦合作用下的行为进行实验研究。对火灾的热释放速率与室内温度场，钢构件及其表面气体的温度、构件在火灾作用下的挠度进行测量，分析真实火灾下钢构件温升及温度分布的特点与火灾发展对构件挠度的影响。研究结果表明钢构件在长向上存在着很大的温差，而构件的挠度变化也并不对称，这说明以往研究中往往假设钢构件在长向上温度一致并不恰当，这种非均匀温度场对构件的行为有着重要影响，它使得构件高温区部分更易发生局部屈服而失效，在相同规模的火灾环境下，与均匀温度场相比，这种墙角火灾所导致的非均匀温度场更不利于钢构件的安全。

关键词： ISO标准火灾实验系统     钢构件     墙角火     温度分布    

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Fast detection algorithm for cracks on tunnel linings based on deep semantic segmentation

《结构与土木工程前沿（英文）》 2023年 第17卷 第5期   页码 732-744 doi: 10.1007/s11709-023-0965-y

摘要： An algorithm based on deep semantic segmentation called LC-DeepLab is proposed for detecting the trends and geometries of cracks on tunnel linings at the pixel level. The proposed method addresses the low accuracy of tunnel crack segmentation and the slow detection speed of conventional models in complex backgrounds. The novel algorithm is based on the DeepLabv3+ network framework. A lighter backbone network was used for feature extraction. Next, an efficient shallow feature fusion module that extracts crack features across pixels is designed to improve the edges of crack segmentation. Finally, an efficient attention module that significantly improves the anti-interference ability of the model in complex backgrounds is validated. Four classic semantic segmentation algorithms (fully convolutional network, pyramid scene parsing network, U-Net, and DeepLabv3+) are selected for comparative analysis to verify the effectiveness of the proposed algorithm. The experimental results show that LC-DeepLab can accurately segment and highlight cracks from tunnel linings in complex backgrounds, and the accuracy (mean intersection over union) is 78.26%. The LC-DeepLab can achieve a real-time segmentation of 416 × 416 × 3 defect images with 46.98 f/s and 21.85 Mb parameters.

关键词： tunnel engineering     crack segmentation     fast detection     DeepLabv3+     feature fusion     attention mechanism    

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Investigating the influence of delamination on the stiffness of composite pipes under compressive transverse

Sattar MALEKI, Roham RAFIEE, Abolfazl HASANNIA, Mohammad Reza HABIBAGAHI

《结构与土木工程前沿（英文）》 2019年 第13卷 第6期   页码 1316-1323 doi: 10.1007/s11709-019-0555-1

摘要： The effect of delamination on the stiffness reduction of composite pipes is studied in this research. The stiffness test of filament wound composite pipes is simulated using cohesive zone method. The modeling is accomplished to study the effect of the geometrical parameters including delamination size and its position with respect to loading direction on stiffness of the composite pipes. At first, finite element results for stiffness test of a perfect pipe without delamination are validated with the experimental results according to ASTM D2412. It is seen that the finite element results agree well with experimental results. Then the finite element model is developed for composite pips with delaminated areas with different primary shapes. Thus, the effect of the size of delaminated region on longitudinal and tangential directions and also its orientation with respect to loading direction on delamination propagation and stiffness reduction of the pipes is assessed.

关键词： delamination     composite pipes     stiffness test     cohesive zone method    

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Ductile extension of 3-D external circumferential cracks in pipe structures

Wuchao YANG, Xudong QIAN

《结构与土木工程前沿（英文）》 2011年 第5卷 第3期   页码 294-303 doi: 10.1007/s11709-011-0115-9

摘要： This study investigates the ductile fracture resistance of 3-D external circumferential cracks in the wall of a steel pipe under remote tension, using a damage-mechanism model originally proposed by Gurson and Tvergaard. The ductile crack extension utilizes an element extinction technique implemented in the computational cell framework. The key parameter for the computational cell method, i.e., the initial porosity ratio , is calibrated using both the fracture resistance and the load-deformation responses obtained from fracture tests of multiple single-edge bend [SE(B)] specimens made of high-strength steel, HY80, which has a yield strength of 630 MPa. The fracture resistance along the 3-D semi-elliptical crack front is computed from the calibrated cell model. Based on the similarity concept in the near-tip stress-strain fields, this study demonstrates that an equivalent 2-D axi-symmetric model provides conservative estimations of the fracture resistance for 3-D circumferential cracks in pipes.

关键词： ductile fracture     computational cell method     G-T model     J-R curve    

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室内装饰材料的标准房间/墙角火实验研究进展

杨昀,张和平,刘激扬

《中国工程科学》 2003年 第5卷 第4期   页码 55-60

摘要：

标准房间/墙角火实验是一种全尺度火灾实验研究方法，主要用来研究室内装饰材料的火灾特性。介绍了ISO 9705房间/墙角火实验方法的原理和实验装置，以及国内外利用该方法对装饰材料火灾特性进行研究的进展情况，包括对材料热释放速率、烟气产生和室内火蔓延方面的研究。分析了其研究成果在室内装饰材料的分类及火灾危险性评估中的实际应用情况，并结合作者目前的工作对未来的研究内容做了一些展望。

关键词： 装饰材料     全尺度     ISO 9705     房间/墙角火实验    

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Effect of calcium lactate on compressive strength and self-healing of cracks in microbial concrete

Kunamineni VIJAY, Meena MURMU

《结构与土木工程前沿（英文）》 2019年 第13卷 第3期   页码 515-525 doi: 10.1007/s11709-018-0494-2

摘要： This paper presents the effect on compressive strength and self-healing capability of bacterial concrete with the addition of calcium lactate. Compared to normal concrete, bacterial concrete possesses higher durability and engineering concrete properties. The production of calcium carbonate in bacterial concrete is limited to the calcium content in cement. Hence calcium lactate is externally added to be an additional source of calcium in the concrete. The influence of this addition on compressive strength, self-healing capability of cracks is highlighted in this study. The bacterium used in the study is and was added to both spore powder form and culture form to the concrete. spore powder of 2 million cfu/g concentration with 0.5% cement was mixed to concrete. Calcium lactates with concentrations of 0.5%, 1.0%, 1.5%, 2.0%, and 2.5% of cement, was added to the concrete mixes to test the effect on properties of concrete. In other samples, cultured with a concentration of 1×10 cells/mL was mixed with concrete, to study the effect of bacteria in the cultured form on the properties of concrete. Cubes of 100 mm×100 mm×100 mm were used for the study. These cubes were tested after a curing period of 7, 14 and 28 d. A maximum of 12% increase in compressive strength was observed with the addition of 0.5% of calcium lactate in concrete. Scanning electron microscope and energy dispersive X-ray spectroscopy examination showed the formation of ettringite in pores; calcium silicate hydrates and calcite which made the concrete denser. A statistical technique was applied to analyze the experimental data of the compressive strengths of cementations materials. Response surface methodology was adopted for optimizing the experimental data. The regression equation was yielded by the application of response surface methodology relating response variables to input parameters. This method aids in predicting the experimental results accurately with an acceptable range of error. Findings of this investigation indicated the influence of added calcium lactate in bio-concrete which is quite impressive for improving the compressive strength and self-healing properties of concrete.

关键词： calcium lactate     bacillus subtilis     compressive strength     self-healing of cracks    

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Fracture behavior of two non-symmetrical collinear cracks emanating from an elliptical hole in a piezoelectric

Junhong GUO, Zixing LU

《机械工程前沿（英文）》 2011年 第6卷 第3期   页码 296-300 doi: 10.1007/s11465-011-0236-9

摘要：

Based on the Stroh-type formalism and the technique of conformal mapping, the problem of two non-symmetrical collinear cracks emanating from an elliptical hole in a piezoelectric solid is investigated under remotely uniform in-plane electric loading and anti-plane mechanical loading, which allowed us to take the electric field inside the hole and cracks into account. The analytical solutions of the field intensity factors and the energy release rate are presented in closed-form, which includes the extreme cases for an impermeable crack and a permeable crack. Numerical results are then presented to reveal the effects of geometrical parameters, crack permeability and combined mechanical and electric loadings on the energy release rate.

关键词： piezoelectric materials     elliptical hole     semi-permeable crack     energy release rate     analytic solution    

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Detecting large-scale underwater cracks based on remote operated vehicle and graph convolutional neural

Wenxuan CAO; Junjie LI

《结构与土木工程前沿（英文）》 2022年 第16卷 第11期   页码 1378-1396 doi: 10.1007/s11709-022-0855-8

摘要： It is of great significance to quickly detect underwater cracks as they can seriously threaten the safety of underwater structures. Research to date has mainly focused on the detection of above-water-level cracks and hasn’t considered the large scale cracks. In this paper, a large-scale underwater crack examination method is proposed based on image stitching and segmentation. In addition, a purpose of this paper is to design a new convolution method to segment underwater images. An improved As-Projective-As-Possible (APAP) algorithm was designed to extract and stitch keyframes from videos. The graph convolutional neural network (GCN) was used to segment the stitched image. The GCN’s m-IOU is 24.02% higher than Fully convolutional networks (FCN), proving that GCN has great potential of application in image segmentation and underwater image processing. The result shows that the improved APAP algorithm and GCN can adapt to complex underwater environments and perform well in different study areas.

关键词： underwater cracks     remote operated vehicle     image stitching     image segmentation     graph convolutional neural network    

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标题 作者 时间 类型 操作

Detection for transverse corner cracks of steel plates’ surface using wavelet

Qiong ZHOU, Qi AN

期刊论文

P60钢轨鱼鳞伤萌生寿命

石嵘,范志毅,何越磊

期刊论文

Microbial self-healing of cracks in cement-based materials and its influencing factors

期刊论文

Shadow obstacle model for realistic corner-turning behavior in crowd simulation

Gao-qi HE,Yi JIN,Qi CHEN,Zhen LIU,Wen-hui YUE,Xing-jian LU

期刊论文

Effect of axial load and transverse reinforcements on the seismic performance of reinforced concrete

Mounir Ait BELKACEM, Hakim BECHTOULA, Nouredine BOURAHLA, Adel Ait BELKACEM

期刊论文

Fatigue crack growth simulations of 3-D linear elastic cracks under thermal load by XFEM

Himanshu PATHAK,Akhilendra SINGH,I.V. SINGH,S. K. YADAV

期刊论文

Investigation of Generalized SIFs of cracks in 3D piezoelectric media under various crack-face conditions

Jaroon RUNGAMORNRAT, Bounsana CHANSAVANG, Weeraporn PHONGTINNABOOT, Chung Nguyen VAN

期刊论文

墙角火灾环境下钢构件温度分布及响应行为的实验研究

陈长坤,姚斌,杨昀,蔡昕,张和平,万玉田

期刊论文

Fast detection algorithm for cracks on tunnel linings based on deep semantic segmentation

期刊论文

Investigating the influence of delamination on the stiffness of composite pipes under compressive transverse

Sattar MALEKI, Roham RAFIEE, Abolfazl HASANNIA, Mohammad Reza HABIBAGAHI

期刊论文

Ductile extension of 3-D external circumferential cracks in pipe structures

Wuchao YANG, Xudong QIAN

期刊论文

室内装饰材料的标准房间/墙角火实验研究进展

杨昀,张和平,刘激扬

期刊论文

Effect of calcium lactate on compressive strength and self-healing of cracks in microbial concrete

Kunamineni VIJAY, Meena MURMU

期刊论文

Fracture behavior of two non-symmetrical collinear cracks emanating from an elliptical hole in a piezoelectric

Junhong GUO, Zixing LU

期刊论文

Detecting large-scale underwater cracks based on remote operated vehicle and graph convolutional neural

Wenxuan CAO; Junjie LI

期刊论文