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i-beam Crack identification Based on Study of Local Flexibility due to Crack

Chinese Journal of Mechanical Engineering 2011年第6期24卷 1116-1122页

作者： Li Bing CHEN Xuefeng HE Zhengjia State Key Laboratory for Manufacturing System Xi’an Jiaotong UniversityXi’an 710072China

Local flexibility of crack plays an important role in crack identification of *** methods on local flexibility in a cracked beam with simple geometric crossing sections,such as rectangle,circle,have been made,but there are some difficulties in calculating local flexibility in a cracked beam with complex crossing section,such as pipe and *** this paper,an analytical method to calculate the local flexibility and rotational spring stiffness due to crack in i-beam is *** local flexibility with respect to various crack depths can be calculated by dividing a cracked i-beam into a series of thin *** forward and inverse problems in crack detection of i-beam are *** forward problem comprises the construction of crack model exclusively for crack section and the construction of a numerically i-beam model to gain crack detection *** inverse problem consists of the measurement of modal parameters and the detection of crack *** experiments including measurement of rotational spring stiffness and prediction of cracks in i-beam are *** results based on the current methods indicate that relative error of crack location is less than 3%,while the error of crack depth identification is less than 6%.Crack identification of i-beam is expected to contribute to the development of automated crack detection techniques for railway lines and building skeletons.

关键词： crack identification i-beam local flexibility

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Experimental Research on Structural Behaviors of Glulam i-beam with a Special-Shaped Section

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Journal of Renewable Materials 2020年第2期8卷 113-132页

作者： Ruyuan Yang Chaokun Hong Xiaofeng Zhang Quan Yuan Youfu Sun College of Materials Science and Engineering Nanjing Forestry UniversityNanjingChina College of Civil Engineering Nanjing Forestry UniversityNanjingChina College of Media and Art Nanjing University of Information Science&TechnologyNanjingChina

in order to enhance the bearing capacity of structural components,save materials,and reduce cost,a glued laminated timber(glulam)i-beam that is theoretically suitable for engineering application was *** this study,18 glulam specimens were fabricated using larch dimension lumber and resorcinol-formaldehyde ***-point bending tests were carried out to compare the ultimate bearing capacity,strain,and deflection of various *** results showed that:(1)The typical failure mode at bending is the web shear failure parallel to *** the failure,cracks and sounds appear at the beam web,which represent the sudden brittle failure.(2)The cross-sectional strain of glulam beam changed linearly with the beam height,indicating that the plane section assumption was basically established.(3)Stiffener could improve the initial flexural stiffness of glulam beam,which experiences an increase of 28.21%.Larger the shear span ratio,smaller the initial flexural *** initial flexural stiffness improves by 10-23.5%with the increase in the thickness of the lower flange.(4)The effects of stiffener and shear-span ratio on shear strength are relatively *** the stiffeners are set at the support and the loading point in pairs,the shear strength of the glulam beam increases by 15.05%*** the increase in the shear-span ratio,the shearing strength of the glulam i-beam gradually *** equation of the shearing strength with the shear span ratio is obtained,which is shown by high fitting precision.(5)The shear strength correlation,as proposed by Soltis and Rammer,is suitable not only for rectangular beams,but also for glulam i-beams.

关键词： Glulam i-beam stiffener shear span ratio flange thickness

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Two Multi-Objective Genetic Algorithms for Finding Optimum Design of an i-beam

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Engineering（科研） 2011年第10期3卷 1054-1061页

作者： Ali Khazaee Hossein Miar Naimi 不详

Many engineering design problems are characterized by presence of several conflicting objectives. This requires efficient search of the feasible design region for optimal solutions which simultaneously satisfy multiple design objectives. Genetic algorithm optimization (GAO) is a powerful search technique with faster convergence rates than traditional evolutionary algorithms. This paper applies two GAO-based approaches to multi-objective engineering design and finds design variables through the feasible space. To demonstrate the utility of the proposed methods, the multi-objective design of an i-beam will be presented.

关键词： Genetic Algorithm Multi-Objective i-beam Optimization

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Laser-Based Guided Wave Propagation and Mode Decomposition in Detecting the integrity of Structural i-beams

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Journal of Computer and Communications 2018年第1期6卷 42-55页

作者： Peter Tse Faeez Masurkar Smart Engineering Asset Management Laboratory (SEAM) and Croucher Optical Non-Destructive Testing and Quality inspection Laboratory (CNDT) Department of Systems Engineering and Engineering Management City University of Hong Kong Hong Kong China

This paper addresses the studies carried out on an i-beam to reveal the wave propagation characteristics and tackle the multi-mode propagation of Lamb waves. The experimental setup consisted of a new 3D Scanning Laser Doppler Vibrometer manufactured by Polytec (3D-SLDV) and was used to acquire high resolution time-space Lamb waves that were propagating in the i-beam. A high power and pulsed Nd:YAG laser was used to emit the required Lamb waves. The emission and sensing of the waves were carried out simultaneously. The wave propagation data was recorded by scanning the surface of the i-beam in a sequential manner. The measured data was used to construct the wave patterns that were propagating in the i-beams at different time instants. Furthermore, as the waves in an i-beam propagate with multiple modes even at low frequency range, filtering was carried out in the frequency-wavenum- ber domain in order to decompose the modes. The results presented thereby confirm that the new 3D-SLDV possesses tremendous capability in revealing the wave propagation characteristics and its interaction with defect. The results could be the first time that the waves propagating in a real i-beam can be visually observed, whilst in the past, it can only be visualized through simulation. The capability of using such totally laser-based 3D inspection system to reveal the characteristics of Lamb wave and its interaction with defects are substantial.

关键词： Laser System i-beam Lamb Waves Mode Decomposition Surface Defect

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Torsional behavior of triangular web profile （TRiWP） steel section by experimental study

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Frontiers of Structural and Civil Engineering 2016年第4期10卷 409-419页

作者： Fatimah DE'NAN Hazwani HASAN Mohd Hanim OSMAN Sariffudin SAAD School of Civil Engineering Engineering Campus Universiti Sains Malaysia Pulau Pinang 14300 Malaysia Faculty of Civil Engineering Universiti Teknologi Malaysia Skudai Johor 8131 O Malaysia

A triangular web profile （TriWP） is a modified section where the flanges are connected to a web plate of triangular profile. This study examined the torsional behavior of TriWP steel sections and compared to that of the fiat web （FW） steel sections. Three types of specimen sizes were used： 180 mmx 75 mm × 5 mm× 2 mm, 200 mm × 100 mm× 8 mm ×6 mm, and 200 mm× 100 mm × 6 mm× 5 mm. All the specimens were loaded vertically until the maximum load was achieved and then the load was released. For both types of specimens, it was observed that the torsional rotation for bigger size [200 mm× 100 mm× 8 mm × 6 mm] were smaller than that of smaller size [ 180 mm × 75 mm×5 mm× 2 mm] of the specimens. At the maximum torsional loading, the experimental result was compared to the theoretical calculation. The comparison showed that the percentage difference ranged from 1.10% to 16.80%. From the graph of torsional load versus rotational angle, the torsional rotation for all TriWP steel sections were smaller than that of the FW steel section under the same torsional loading i.e., 0.2 kNm and 1 kNm. The range between FW and TriWP were 3.74 to 71.83 at 0.2 kNm while 14.5 to 75.1 at 1.0 kNm. The findings were shown that the TriWP steel sections had better resistance against torsion in comparison to FW steel section.

关键词： corrugated web i-beam non uniform steel section torsion resistance torsion angle triangular web profile steel section

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MRi异常癫痫患者瞬态地形图定位研究

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功能性和立体定向神经外科杂志 1998年第3期11卷 26-27页

作者：司志国边进东阚凤杰河北省唐山工人医院

目的：研究临床癫痫发作的患者ＩＢＥＡＭ“致痫灶”与其头部ＭＲＩ有异常病变以及ＶＥＥＧ有棘波、尖波或棘慢波、尖慢波发放的符合率。方法：利用２４小时ＶＥＥＧ（视频脑电图）监测癫痫患者；选出头部ＭＲＩ有异常改变、Ｖ... 详细信息

目的：研究临床癫痫发作的患者ＩＢＥＡＭ“致痫灶”与其头部ＭＲＩ有异常病变以及ＶＥＥＧ有棘波、尖波或棘慢波、尖慢波发放的符合率。方法：利用２４小时ＶＥＥＧ（视频脑电图）监测癫痫患者；选出头部ＭＲＩ有异常改变、ＶＥＥＧ有棘波、尖波、棘慢波、尖慢波发放的患者４６例，进行ＩＢＥＡＭ描记。结果：ＭＲＩ显示病变部位和ＩＢＥＡＭ彩色图形显示一致者１９例，符合率为４１．３％。基底节病变，其ＩＢＥＡＭ亦以病变侧，或双侧颞、颞顶部显示。结论：ＩＢＥＡＭ和影像检查相配合，可为“致痫灶”提供较可靠指标。今后结合无创性“偶极子”定位法研究，将会使癫痫患者“致痫灶”

关键词：癫痫 V-EEG i-beam 脑电图

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