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An analytical method for calculating torsional constants for arbitrary complicated thin-walled cross-sections

DU Baisong, GE Yaojun, ZHOU Zheng

《结构与土木工程前沿（英文）》 2007年第1卷第3期页码 293-297 doi: 10.1007/s11709-007-0038-7

摘要： In this paper, an analytical method is proposed for calculating torsional constants for complicated thin-walled cross-sections with arbitrary closed or open rib stiffeners. This method uses the free torsional theory and the principle of virtual work to build governing equilibrium equations involving unknown shear flows and twisting rate. After changing the form of the equations and combining these two unknowns into one, torsional function, which is a function of shear flow, shear modulus, and twisting rate, is included in the governing equations as only one of the unknowns. All the torsional functions can be easily obtained from these homogeneous linear equations, and torsional constants can be easily obtained from the torsional functions. The advantage of this method is that we can easily and directly obtain torsional constants from the torsional functions, rather than the more sophisticated shear flow and twisting rate calculations. Finally, a complicated thin-walled cross-section is given as a valid numerical example to verify the analytical method, which is much more accurate and simpler than the traditional finite element method.

关键词： homogeneous complicated thin-walled numerical example advantage torsional function

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Mechanism of self-excited torsional vibration of locomotive driving system

Jianxin LIU, Huaiyun ZHAO, Wanming ZHAI

《机械工程前沿（英文）》 2010年第5卷第4期页码 465-469 doi: 10.1007/s11465-010-0115-9

摘要： A single wheelset drive model and 2-DOFs torsional vibration model were established to investigate the self-excited torsional vibration of a locomotive driving system. The simulation results indicate that the self-excited torsional vibration occurs when the steady slip velocity is located at the descending slope of the adhesion coefficient curve. The principle of energy conservation was used to analyze the mechanism of the self-excited vibration. The factors affecting on the amplitude of the self-excited vibration are studied.

关键词： locomotive driving system self-excited torsional vibration mechanism influence factor

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Flexural-torsional buckling behavior of aluminum alloy beams

Xiaonong GUO,Zhe XIONG,Zuyan SHEN

《结构与土木工程前沿（英文）》 2015年第9卷第2期页码 163-175 doi: 10.1007/s11709-014-0272-8

摘要： This paper presents an investigation on the flexural-torsional buckling behavior of aluminum alloy beams (AAB). First, based on the tests of 14 aluminum alloy beams under concentrated loads, the failure pattern, load-deformation curves, bearing capacity and flexural-torsional buckling factor are studied. It is found that all the beam specimens collapsed in the flexural-torsional buckling with excessive deformation pattern. Moreover, the span, loading location and slenderness ratio influence the flexural-torsional buckling capacity of beams significantly. Secondly, besides the experiments, a finite element method (FEM) analysis on the flexural-torsional buckling behavior of AAB is also conducted. The main parameters in the FEM analysis are initial imperfection, material property, cross-section and loading scheme. According to the analytical results, it is indicated that the FEM is reasonable to capture mechanical behavior of AAB. Finally, on the basis of the experimental and analytical results, theoretical formulae to estimate the flexural-torsional buckling capacity of AAB are proposed, which could improve the application of present codes for AAB.

关键词： flexural-torsional buckling aluminum alloy beams (AAB) finite element method (FEM) theoretical formula

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A novel structural modification to eliminate the early coupling between bending and torsional mode shapes

Nazim Abdul NARIMAN

《结构与土木工程前沿（英文）》 2017年第11卷第2期页码 131-142 doi: 10.1007/s11709-016-0376-4

摘要： In this paper, a novel structural modification approach has been adopted to eliminate the early coupling between the bending and torsional mode shapes of vibrations for a cable stayed bridge model generated using ABAQUS software. Two lateral steel beams are added to the middle span of the structure. Frequency analysis is dedicated to obtain the natural frequencies of the first eight mode shapes of vibrations before and after the structural modification approach. Numerical simulations of wind excitations are conducted for the 3D model of the cable stayed bridge with duration of 30 s supporting on real data of a strong wind from the literature. Both vertical and torsional displacements are calculated at the mid span of the deck to analyze both the bending and the torsional stiffness of the system before and after the structural modification. The results of the frequency analysis after applying lateral steel beams declared a safer structure against vertical and torsional vibrations and rarely expected flutter wind speed. Furthermore, the coupling between the vertical and torsional mode shapes has been removed to larger natural frequencies magnitudes with a high factor of safety. The novel structural approach manifested great efficiency in increasing vertical and torsional stiffness of the structure.

关键词： aeroelastic instability structural damping flutter wind speed bending stiffness torsional stiffness

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Lateral-torsional buckling capacity assessment of web opening steel girders by artificial neural networks

Yasser SHARIFI,Sajjad TOHIDI

《结构与土木工程前沿（英文）》 2014年第8卷第2期页码 167-177 doi: 10.1007/s11709-014-0236-z

摘要： Bridge girders exposed to aggressive environmental conditions are subject to time-variant changes in resistance. There is therefore a need for evaluation procedures that produce accurate predictions of the load-carrying capacity and reliability of bridge structures to allow rational decisions to be made about repair, rehabilitation and expected life-cycle costs. This study deals with the stability of damaged steel I-beams with web opening subjected to bending loads. A three-dimensional (3D) finite element (FE) model using ABAQUS for the elastic flexural torsional analysis of I-beams has been used to assess the effect of web opening on the lateral buckling moment capacity. Artificial neural network (ANN) approach has been also employed to derive empirical formulae for predicting the lateral-torsional buckling moment capacity of deteriorated steel I-beams with different sizes of rectangular web opening using obtained FE results. It is found out that the proposed formulae can accurately predict residual lateral buckling capacities of doubly-symmetric steel I-beams with rectangular web opening. Hence, the results of this study can be used for better prediction of buckling life of web opening of steel beams by practice engineers.

关键词： steel I-beams lateral-torsional buckling finite element (FE) method artificial neural network (ANN) approach

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Proposing two new methods to decrease lateral-torsional buckling in reduced beam section connections

Samira EBRAHIMI; Nasrin BAKHSHAYESH EGHBALI; Mohammad Mehdi AHMADI

《结构与土木工程前沿（英文）》 2022年第16卷第12期页码 1581-1598 doi: 10.1007/s11709-022-0886-1

摘要： Reduced web section (RWS) connections can prevent lateral-torsional buckling and web local buckling experienced by reduced beam section (RBS) connections. In RWS connections, removing a large portion of web can result in shear demand intolerance induced to plastic hinge region. The present study aims to resolve the problems of RBS and RWS connections by proposing two new connections: (1) RBS with stiffener (RBS-ST) and (2) RBS with reduced web (RW-RBS) connections. In the first connection (RBS-ST), a series of stiffeners is connected to the beam in the reduced flange region, while the second connection (RW-RBS) considers both a reduction in flanges and a reduction in web. Five beam-to-column joints with three different connections, including RBS, RBS-ST, and RW-RBS connections were considered and simulated in ABAQUS. According to the results, RBS-ST and RW-RBS connections can decrease or even eliminate lateral-torsional buckling and web local buckling in RBS connection. It is important to note that RW-RBS connection is more effective in long beams with smaller shear demands in the plastic hinge region. Moreover, results showed that RBS and RW-RBS connections experienced strength degradation at 4% to 5% drift, while no strength degradation was observed in RBS-ST connection until 8% drift.

关键词： RBS RBS-ST RW-RBS lateral-torsional buckling cyclic performance

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Hole quality in longitudinal–torsional coupled ultrasonic vibration assisted drilling of carbon fiber

Guofeng MA, Renke KANG, Zhigang DONG, Sen YIN, Yan BAO, Dongming GUO

《机械工程前沿（英文）》 2020年第15卷第4期页码 538-546 doi: 10.1007/s11465-020-0598-y

摘要： Carbon fiber reinforced plastic (CFRP) composites are extremely attractive in the manufacturing of structural and functional components in the aircraft manufacturing field due to their outstanding properties, such as good fatigue resistance, high specific stiffness/strength, and good shock absorption. However, because of their inherent anisotropy, low interlamination strength, and abrasive characteristics, CFRP composites are considered difficult-to-cut materials and are prone to generating serious hole defects, such as delamination, tearing, and burrs. The advanced longitudinal–torsional coupled ultrasonic vibration assisted drilling (LTC-UAD) method has a potential application for drilling CFRP composites. At present, LTC-UAD is mainly adopted for drilling metal materials and rarely for CFRP. Therefore, this study analyzes the kinematic characteristics and the influence of feed rate on the drilling performance of LTC-UAD. Experimental results indicate that LTC-UAD can reduce the thrust force by 39% compared to conventional drilling. Furthermore, LTC-UAD can decrease the delamination and burr factors and improve the surface quality of the hole wall. Thus, LTC-UAD is an applicable process method for drilling components made with CFRP composites.

关键词： longitudinal–torsional coupled ultrasonically drilling CFRP thrust force hole quality

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Torsional vibrations of a cylindrical foundation embedded in a saturated poroelastic half-space

Dazhi WU,Lu YU

《结构与土木工程前沿（英文）》 2015年第9卷第2期页码 194-202 doi: 10.1007/s11709-015-0292-z

摘要： Considering the interactions between an embedded foundation and saturated soil, the torsional vibrations of a cylindrical foundation embedded in a saturated poroelastic medium are analyzed in this paper. Both a rigid foundation and an elastic foundation are considered. Assuming both the side surface and the bottom surface of the foundation are perfectly bonded to soil, the reaction torques that the side soil and bottom soil acting on the foundation can be gained from basic dynamic equations of the poroelastic medium. According to the dynamic equilibrium equations of a foundation under harmonic torque, the torsional vibrations of an embedded cylindrical foundation are presented. Besides, the angular amplitude of the foundation, the equivalent stiffness and damping coefficients of the soil are expressed explicitly. Selected examples are presented to investigate the influence of relevant parameters on the torsional vibrations.

关键词： embedded foundation saturated soil rigid foundation elastic foundation torsional vibration

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Sensitivity analysis of torsional vibration behavior of the shafting of a turbo generator set to changes

XIE Danmei, ZHANG Hengliang, DONG Chuan, LIU Zhanhui, YANG Changzhu

《能源前沿（英文）》 2007年第1卷第4期页码 483-486 doi: 10.1007/s11708-007-0072-4

摘要： Aiming at a 300 MW turbo-generator model, the sensitivity of natural torsional frequencies and modes of torsional vibration (TV) to the rotational inertia and stiffness of the turbo-generator were analyzed. Calculation results show

关键词： Calculation MW turbo-generator sensitivity stiffness

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Control of wind-induced vibration of long-span bridges and tall buildings

GU Ming

《结构与土木工程前沿（英文）》 2007年第1卷第1期页码 51-62 doi: 10.1007/s11709-007-0005-3

摘要： With the rapid increase in scales of structures, research on controlling wind-induced vibration of large-scale structures, such as long-span bridges and super-tall buildings, has been an issue of great concern. For wind-induced vibration of large-scale structures, vibration frequencies and damping modes vary with wind speed. Passive, semiactive, and active control strategies are developed to improve the wind-resistance performance of the structures in this paper. The multiple tuned mass damper (MTMD) system is applied to control vertical bending buffeting response. A new semiactive lever-type tuned mass damper (TMD) with an adjustable frequency is proposed to control vertical bending buffeting and torsional buffeting and flutter in the whole velocity range of bridge decks. A control strategy named sinusoidal reference strategy is developed for adaptive control of wind-induced vibration of super-tall buildings. Multiple degrees of freedom general building aeroelastic model with a square cross-section is tested in a wind tunnel. The results demonstrate that the proposed strategies can reduce vibration effectively, and can adapt to wind-induced vibration control of large-scale structures in the uncertain dynamic circumstance.

关键词： torsional buffeting large-scale semiactive adjustable frequency building aeroelastic

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Lung function and air pollution exposure in adults with asthma in Beijing: a 2-year longitudinal panel

《医学前沿（英文）》 2022年第16卷第4期页码 574-583 doi: 10.1007/s11684-021-0882-1

摘要： The effect of air pollution on the lung function of adults with asthma remains unclear to date. This study followed 112 patients with asthma at 3-month intervals for 2 years. The pollutant exposure of the participants was estimated using the inverse distance weight method. The participants were divided into three groups according to their lung function level at every visit. A linear mixed-effect model was applied to predict the change in lung function with each unit change in pollution concentration. Exposure to carbon monoxide (CO) and particles less than 2.5 micrometers in diameter (PM_2.5) was negatively associated with large airway function in participants. In the severe group, exposure to chronic sulfur dioxide (SO₂) was negatively associated with post-bronchodilator forced expiratory flow at 50%, between 25% and 75% of vital capacity % predicted (change of 95% CI per unit: −0.34 (−0.55, −0.12), −0.24 (−0.44, −0.03), respectively). In the mild group, the effect of SO₂ on the small airways was similar to that in the severe group, and it was negatively associated with large airway function. Exposure to CO and PM_2.5 was negatively associated with the large airway function of adults with asthma. The negative effects of SO₂ were more evident and widely observed in adults with severe and mild asthma than in adults with moderate asthma. Patients with asthma react differently to air pollutants as evidenced by their lung function levels.

关键词： lung function asthma air pollution adult

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The function and regulation of OTU deubiquitinases

Jiansen Du, Lin Fu, Yingli Sui, Lingqiang Zhang

《医学前沿（英文）》 2020年第14卷第5期页码 542-563 doi: 10.1007/s11684-019-0734-4

摘要： Post-translational modification of cellular proteins by ubiquitin regulates numerous cellular processes, including cell division, immune responses, and apoptosis. Ubiquitin-mediated control over these processes can be reversed by deubiquitinases (DUBs), which remove ubiquitin from target proteins and depolymerize polyubiquitin chains. Recently, much progress has been made in the DUBs. In humans, the ovarian tumor protease (OTU) subfamily of DUBs includes 16 members, most of which mediate cell signaling cascades. These OTUs show great variation in structure and function, which display a series of mechanistic features. In this review, we provide a comprehensive analysis of current progress in character, structure and function of OTUs, such as the substrate specificity and catalytic activity regulation. Then we discuss the relationship between some diseases and OTUs. Finally, we summarize the structure of viral OTUs and their function in immune escape and viral survival. Despite the challenges, OTUs might provide new therapeutic targets, due to their involvement in key regulatory processes.

关键词： ubiquitin OTU deubiquitinases structure function regulation

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类差分平衡函数的性质及其应用

张文英,李世取

《中国工程科学》 2004年第6卷第3期页码 45-52

摘要：

定义了布尔函数的类差分和类差分平衡函数，研究了类差分平衡函数的密码学性质以及构造方法。作为类差分平衡函数的应用，给出了〓上逻辑函数是完全非线性函数的充要条件，并在首先分析得到所有四元类差分平衡函数的基础上，编程搜索出〓上所有的完全非线性函数。

关键词： Bent函数完全非线性函数 2-基展开类差分类自相关函数类差分平衡函数

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Quality Function Deployment Implementation in Construction: A Systematic Literature Review

Elizabeth A. Cudney,William L. Gillis

《工程管理前沿（英文）》 2016年第3卷第3期页码 224-230 doi: 10.15302/J-FEM-2016036

摘要： The construction of new buildings represents a significant investment. The goal of new building construction is to maximize value and minimize cost while staying on time and within budget. Translating customer requirements into engineering terms for new construction design is vital for a construction project to be successful. Quality function deployment has been successfully used in product development to capture the voice of the customer and translate it into engineering characteristics. Quality function deployment then carries these parameters into production and service to ensure the voice of the customer is being met with the final product. The house of quality, a tool within quality function deployment, can provide a means for comparison of owner’s project requirements and the proposed design, along with identifying how the design decisions impact meeting customer requirements and green building requirements. Quality function deployment can effectively link the project phases through design and construction and into operations and maintenance to ensure the owner’s project requirements are met with the final building. This research identifies and categorizes studies of quality function deployment applications in construction. The research method used is a systematic literature review from databases related to quality function deployment in the construction industry published in the periodicals through 2016. The principal findings of implementations, practices, and integrated approaches are then summarized. This article intends to propel further research of quality function deployment in the construction sector.

关键词： construction engineering management quality function deployment systematic review

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Design and evaluation of a novel biopsy needle with hemostatic function

《机械工程前沿（英文）》 2023年第18卷第2期 doi: 10.1007/s11465-022-0738-7

摘要： Biopsy is a method commonly used for early cancer diagnosis. However, bleeding complications of widely available biopsy are risky for patients. Safer biopsy will result in a more accurate cancer diagnosis and a decrease in the risk of complications. In this article, we propose a novel biopsy needle that can reduce bleeding during biopsy procedures and achieve stable hemostasis. The proposed biopsy needle features a compact structure and can be operated easily by left and right hands. A predictive model for puncture force and tip deflection based on coupled Eulerian–Lagrangian (CEL) method is developed. Experimental results show that the biopsy needle can smoothly deliver the gelatin sponge hemostatic plug into the tissue. Although the hemostatic plug bends, the overall delivery process is stable, and the hemostatic plug retains in the tissue without being affected by the withdrawal of the needle. Further experiments indicate that the specimens are well obtained and evenly distributed in the groove of the outer needle without scattering. Our proposed design of biopsy needle possesses strong ability of hemostasis, tissue cutting, and tissue retention. The CEL model accurately predicts the peak of puncture force and produces close estimation of the insertion force at the postpuncture stage and tip position.

关键词： cancer diagnosis biopsy needle hemostatic function predictive model coupled Eulerian−Lagrangian