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Investigation of fatigue resistance of fillet-welded tube connection details for sign support structures

Hyungjoo CHOI, Husam NAJM

《结构与土木工程前沿（英文）》 2020年 第14卷 第1期   页码 199-214 doi: 10.1007/s11709-019-0592-9

摘要： Stiffened and unstiffened fillet-welded tube-to-transverse plate connection details are widely used for mast-arm and base-plate connections for highway sign structures. However, due to repetitive wind loads, cyclic fatigue stresses are induced and they are the primary source of failure in welded connections at these locations. The resistance of fatigue critical details has been an on-going research topic because of limited experimental results and the variability in existing fatigue testing results. The main objective of this study is to evaluate fatigue resistance of fillet-welded tube connection details by utilizing the advanced fatigue tool in ANSYS Workbench platform. Finite Element (FE) models development and model validation using existing test data was presented. The resulting fatigue resistance from FE analysis was expressed in terms of fatigue life, fatigue damage, and fatigue safety factor to determine the fatigue performance of fillet-welded connections. Existing fatigue test data was grouped to perform a synthetic analysis and then analysis results were provided to determine input data and fatigue limit for the fatigue module. The local stress level at fatigue critical locations was evaluated using a static FE model for different number of stiffeners and boundary conditions. The results of this investigation provides fatigue resistance of fillet-welded connection details in the form of fatigue life, fatigue damage and safety factor for various connection parameters and structural conditions.

关键词： fatigue     weld connections     base plate     fillet welds    

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Multi-objective optimization of surface texture for the slipperswash plate interface in EHA pumps

《机械工程前沿（英文）》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0704-4

摘要： Well-designed surface textures can improve the tribological properties and the efficiency of the electro-hydrostatic actuator (EHA) pump under high-speed and high-pressure conditions. This study proposes a multi-objective optimization model to obtain the arbitrarily surface textures design of the slipper/swash plate interface for improving the mechanical and volumetric efficiency of the EHA pump. The model is composed of the lubrication film model, the component dynamic model considering the spinning motion, and the multi-objective optimization model. In this way, the arbitrary-shaped surface texture with the best comprehensive effect in the EHA pump is achieved and its positive effects in the EHA pump prototype are verified. Experimental results show a reduction in wear and an improvement in mechanical and volumetric efficiency by 1.4% and 0.8%, respectively, with the textured swash plate compared with the untextured one.

关键词： electro-hydrostatic actuator     axial piston pump     slipper/swash plate interface     multi-objective optimization     surface texture    

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Initial stiffness and moment resistance of reinforced joint with end-plate connection

Sufang WANG, Yiyi CHEN,

《结构与土木工程前沿（英文）》 2009年 第3卷 第4期   页码 345-351 doi: 10.1007/s11709-009-0054-x

摘要： In beam-to-column joint with bolted end-plate connection, the structural details of column flange reinforced by backing plate and column web panel reinforced by supplementary plate are analyzed. The joint is divided into some basic components, and the initial stiffness of each component is obtained. Especially, the initial stiffness of reinforced components is drawn by theoretical model and finite element analysis. The initial stiffness of reinforced joint can be obtained by assembling the initial stiffness of each component. The design moment resistance of column flange reinforced by backing plate is deduced based on yield line method, and the design moment resistances of other components are deduced based on present codes. The design moment resistance of the reinforced joint is then determined by the minimum of the design moment resistances of all components. By comparison with the results of finite element calculation, it is verified that the method to calculate the initial stiffness of reinforced joint is accurate enough to be used to estimate the rigid behavior of the joint and to make parametric study.

关键词： steel structure     end-plate connection     backing plate     supplementary web plate     initial stiffness     moment resistance    

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Study of base friction simulation tests based on a complicated engineered bridge slope

Liu HE, Guang WU, Hua WANG

《结构与土木工程前沿（英文）》 2012年 第6卷 第4期   页码 393-397 doi: 10.1007/s11709-012-0174-6

摘要： In this paper, a physical base friction test model of a slope is established. The model is based on similarity principles and the geological conditions of a complicated bridge slope during construction, deformation and failure. The behavior of the slope in both its natural state and during excavation loading is qualitatively analyzed through base friction tests. The base friction test results are then subjected to comparison and analysis using finite element numerical simulation. The findings show that the whole engineered slope tends to stabilize in its natural state, whereas instabilities will arise at faulted rock masses located near bridge piers during excavation loading. Therefore, to ensure normal construction operation of bridge works, it is suggested that pre-reinforcement of faulted rock masses be performed.

关键词： base friction test     slope stability evaluation     bridge slope    

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On the improvement design of dynamic characteristics for the roller follower of a variable-speed plate

Hui Ching FAN, Hong Sen YAN

《机械工程前沿（英文）》 2012年 第7卷 第1期   页码 5-15 doi: 10.1007/s11465-012-0310-y

摘要：

Without modifying the cam contour, a cam mechanism with a variable input speed trajectory offers an alternative solution to flexibly achieve kinematic and dynamic characteristics, and then decrease the follower’s residual vibration. Firstly, the speed trajectory of cam is derived by employing Bezier curve, and motion continuity conditions are investigated. Then the motion characteristics between the plate cam and its roller follower are derived. To analyze the residual vibration, a single degree of freedom dynamic model of the elastic cam-follower system is introduced. Based on the motion equation derived from the dynamic model, the residual vibration of the follower is yielded. The design procedure to improve the kinematic and dynamic motion characteristics is presented and two design examples with discussions are provided. Finally, the simulations of the kinematic and dynamic models by ADAMS are carried out and verified that the design models as well as the performances of the mechanism are feasible.

关键词： cam mechanism     variable input speed     kinematic design     dynamic design     optimal design    

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Frequencies of circular plate with concentric ring and elastic edge support

null

《机械工程前沿（英文）》 2014年 第9卷 第2期   页码 168-176 doi: 10.1007/s11465-014-0299-5

摘要：

Exact solutions for the flexural vibrations of circular plates having elastic edge conditions along with rigid concentric ring support have been presented in this paper. Values of frequency parameter for the considered circular plate are computed for different sets of values of elastic rotational and translation restraints and the radius of internal rigid ring support. The results for the first three modes of plate vibrations are computed and are presented in tabular form. The effects of rotational and linear restraints and the radius of the rigid ring support on the vibration behavior of circular plates are studied over a wide range of non-dimensional parametric values. The values of the exact frequency parameter presented in this paper for varying values of restraint parameters and the radius of the rigid ring support can better serve in design and as benchmark solutions to validate the numerical methods obtained by using other methods of solution.

关键词： circular plate     frequency     elastic edge     rigid ring     mode switching    

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Linear ultrasonic motor using quadrate plate transducer

Jiamei JIN, Chunsheng ZHAO

《机械工程前沿（英文）》 2009年 第4卷 第1期   页码 88-91 doi: 10.1007/s11465-009-0016-y

摘要： A linear ultrasonic motor using a quadrate plate transducer was developed for precision positioning. This motor consists of two pairs of Pb(Zr,Ti)O piezoelectric ceramic elements, which are piezoelectrically excited into the second-bending mode of the motor stator’s neutral surface in two orthogonal directions, on which the tops of four projections move along an elliptical trajectory, which in turn drives a contacted slider into linear motion via frictional forces. The coincident frequency of the stator is easily obtained for its coincident characteristic dimension in two orthogonal directions. The performance characteristics achieved by the motor are: 1) a maximum linear speed of more than 60 mm/s; 2) a stroke of more than150 mm; 3) a driving force of more than 5.0 N; and 4) a response time of about 2 ms.

关键词： ultrasonic motor     quadrate plate     coincident frequency     alternant contact    

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Progressive failure analysis of notched composite plate by utilizing macro mechanics approach

《结构与土木工程前沿（英文）》 2021年 第15卷 第3期   页码 623-642 doi: 10.1007/s11709-021-0726-8

摘要： In this study, gradual and sudden reduction methods were combined to simulate a progressive failure in notched composite plates using a macro mechanics approach. Using the presented method, a progressive failure is simulated based on a linear softening law prior to a catastrophic failure, and thereafter, sudden reduction methods are employed for modeling a progressive failure. This combination method significantly reduces the computational cost and is also capable of simultaneously predicting the first and last ply failures (LPFs) in composite plates. The proposed method is intended to predict the first ply failure (FPF), LPF, and dominant failure modes of carbon/epoxy and glass/epoxy notched composite plates. In addition, the effects of mechanical properties and different stacking sequences on the propagation of damage in notched composite plates were studied. The results of the presented method were compared with experimental data previously reported in the literature. By comparing the numerical and experimental data, it is revealed that the proposed method can accurately simulate the failure propagation in notched composite plates at a low computational cost.

关键词： progressive failure     notched composite plate     Hashin failure criterion     macro mechanics approach     finite element method    

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Comprehensive comparison of small-scale natural gas liquefaction processes using brazed plate heat exchangers

Jitan WU, Yonglin JU

《能源前沿（英文）》 2020年 第14卷 第4期   页码 683-698 doi: 10.1007/s11708-020-0705-0

摘要： The brazed plate heat exchanger (BPHE) has some advantages over the plate-fin heat exchanger (PFHE) when used in natural gas liquefaction processes, such as the convenient installation and transportation, as well as the high tolerance of carbon dioxide (CO ) impurities. However, the BPHEs with only two channels cannot be applied directly in the conventional liquefaction processes which are designed for multi-stream heat exchangers. Therefore, the liquefaction processes using BPHEs are different from the conventional PFHE processes. In this paper, four different liquefaction processes using BPHEs are optimized and comprehensively compared under respective optimal conditions. The processes are compared with respect to energy consumption, economic performance, and robustness. The genetic algorithm (GA) is applied as the optimization method and the total revenue requirement (TRR) method is adopted in the economic analysis. The results show that the modified single mixed refrigerant (MSMR) process with part of the refrigerant flowing back to the compressor at low temperatures has the lowest specific energy consumption but the worst robustness of the four processes. The MSMR with fully utilization of cold capacity of the refrigerant shows a satisfying robustness and the best economic performance. The research in this paper is helpful for the application of BPHEs in natural gas liquefaction processes.

关键词： liquefied natural gas     brazed plate heat exchanger     energy consumption     economic performance     robustness    

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Fundamental frequency and testing mode of complicated elastic clamped-plate vibration

QI Hongyuan, GUAN Yiduo

《机械工程前沿（英文）》 2008年 第3卷 第4期   页码 360-364 doi: 10.1007/s11465-008-0084-4

摘要： Aimed at the modal analysis of complicated elastic clamped-plates, a trigonometric interpolation method of conformal mapping is applied to set up the mapping function between a complicated region and a unit dish region, and the fundamental frequency of the complicated vibrating region is analyzed with the help of the Galerkin method. Taking an elastic rectangle-plate with arc radius as an example, the testing mode frequency band of plates is determined by analyzing the fundamental frequency; meanwhile, according to hamming testing method of multi-point excitation to the single-point response, and by signal processing technology and its software programming, modal parameter recognition of the elastic clamped-plate is completed. Comparing the first order modal frequency with the theoretical fundament frequency, the validity of the testing mode method and theoretical analysis are verified.

关键词： multi-point excitation     rectangle-plate     single-point     processing technology     trigonometric interpolation    

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Magnetohydrodynamic slip flow and diffusion of a reactive solute past a permeable flat plate with suction

Krishnendu BHATTACHARYYA, G. C. LAYEK

《化学科学与工程前沿（英文）》 2011年 第5卷 第4期   页码 471-476 doi: 10.1007/s11705-011-1130-z

摘要： The magnetohydrodynamic (MHD) boundary layer slip flow and solute transfer over a porous plate in the presence of a chemical reaction are investigated. The governing equations were transformed into self-similar ordinary differential equations by adopting the similarity transformation technique. Then the numerical solutions are obtained by a shooting technique using the fourth order Runge-Kutta method. The study reveals that due to the increase in the boundary slip, the concentration decreases and the velocity increases. On the other hand, with an increase in the magnetic field and mass suction, both boundary layer thicknesses decreased. As the Schmidt number and the reaction rate parameter increases, the concentration decreases and the mass transfer increases.

关键词： slip flow     MHD boundary layer     reactive solute diffusion     flat plate     suction/injection    

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Effect of size on biaxial flexural strength for cement-based materials by using a triangular plate method

Hakan T TURKER

《结构与土木工程前沿（英文）》 2022年 第16卷 第8期   页码 1017-1028 doi: 10.1007/s11709-022-0871-8

摘要： The effect of size on the biaxial flexural strength (BFS) of Portland cement mortar was investigated by using the recently proposed triangular plate method (TPM). An experimental program was conceived to study the size effect by keeping a constant water-cement ratio of 0.485, cement-sand ratio of 1:2.75, and using unreinforced triangular mortar plates of five different thicknesses and seven different side lengths. The BFS of the produced specimens was tested, and variations of BFS depending on specimen thickness and side length were determined. The results indicated that increases in triangular plate specimen side length and specimen thickness led to a decrease in the BFS of Portland cement mortar. The effect of specimen length increase on BFS was more significant than on the effect of the specimen thickness. The variations in specimens’ thickness indicated a deterministic Type I size effect, while the variations in specimens’ length showed an energetic-statistical Type I size effect.

关键词： testing     apparatus & methods     plain concrete     tensile properties     biaxial flexural strength     triangular plate method    

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Base editors: development and applications in biomedicine

《医学前沿（英文）》 2023年 第17卷 第3期   页码 359-387 doi: 10.1007/s11684-023-1013-y

摘要： Base editor (BE) is a gene-editing tool developed by combining the CRISPR/Cas system with an individual deaminase, enabling precise single-base substitution in DNA or RNA without generating a DNA double-strand break (DSB) or requiring donor DNA templates in living cells. Base editors offer more precise and secure genome-editing effects than other conventional artificial nuclease systems, such as CRISPR/Cas9, as the DSB induced by Cas9 will cause severe damage to the genome. Thus, base editors have important applications in the field of biomedicine, including gene function investigation, directed protein evolution, genetic lineage tracing, disease modeling, and gene therapy. Since the development of the two main base editors, cytosine base editors (CBEs) and adenine base editors (ABEs), scientists have developed more than 100 optimized base editors with improved editing efficiency, precision, specificity, targeting scope, and capacity to be delivered in vivo, greatly enhancing their application potential in biomedicine. Here, we review the recent development of base editors, summarize their applications in the biomedical field, and discuss future perspectives and challenges for therapeutic applications.

关键词： base editing     CBE     ABE     ADAR     DdCBE     disease model     therapeutic application    

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Multistage-batch bipolar membrane electrodialysis for base production from high-salinity wastewater

《化学科学与工程前沿（英文）》 2022年 第16卷 第5期   页码 764-773 doi: 10.1007/s11705-021-2114-2

摘要： Bipolar membrane electrodialysis (BMED) is considered a state-of-the-art technology for the conversion of salts into acids and bases. However, the low concentration of base generated from a traditional BMED process may limit the viability of this technology for a large-scale application. Herein, we report an especially designed multistage-batch (two/three-stage-batch) BMED process to increase the base concentration by adjusting different volume ratios in the acid (Vacid), base (Vbase), and salt compartments (Vsalt). The findings indicated that performance of the two-stage-batch with a volume ratio of Vacid:Vbase:Vsalt = 1:1:5 was superior in comparison to the three-stage-batch with a volume ratio of Vacid:Vbase:Vsalt = 1:1:2. Besides, the base concentration could be further increased by exchanging the acid produced in the acid compartment with fresh water in the second stage-batch process. With the two-stage-batch BMED, the maximum concentration of the base can be obtained up to 3.40 mol∙L–1, which was higher than the most reported base production by BMED. The low energy consumption and high current efficiency further authenticate that the designed process is reliable, cost-effective, and more productive to convert saline water into valuable industrial commodities.

关键词： bipolar membrane electrodialysis     multistage-batch     base production     high-salinity wastewater    

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Enzyme@bismuth-ellagic acid: a versatile platform for enzyme immobilization with enhanced acid-base stability

《化学科学与工程前沿（英文）》 2023年 第17卷 第6期   页码 784-794 doi: 10.1007/s11705-022-2278-4

摘要： In situ encapsulation is an effective way to synthesize enzyme@metal–organic framework biocatalysts; however, it is limited by the conditions of metal–organic framework synthesis and its acid-base stability. Herein, a biocatalytic platform with improved acid-base stability was constructed via a one-pot method using bismuth-ellagic acid as the carrier. Bismuth-ellagic acid is a green phenol-based metal–organic framework whose organic precursor is extracted from natural plants. After encapsulation, the stability, especially the acid-base stability, of amyloglucosidases@bismuth-ellagic acid was enhanced, which remained stable over a wide pH range (2–12) and achieved multiple recycling. By selecting a suitable buffer, bismuth-ellagic acid can encapsulate different types of enzymes and enable interactions between the encapsulated enzymes and cofactors, as well as between multiple enzymes. The green precursor, simple and convenient preparation process provided a versatile strategy for enzymes encapsulation.

关键词： bismuth-ellagic acid     in situ encapsulation     enzyme@MOF biocomposites    

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标题 作者 时间 类型 操作

Investigation of fatigue resistance of fillet-welded tube connection details for sign support structures

Hyungjoo CHOI, Husam NAJM

期刊论文

Multi-objective optimization of surface texture for the slipperswash plate interface in EHA pumps

期刊论文

Initial stiffness and moment resistance of reinforced joint with end-plate connection

Sufang WANG, Yiyi CHEN,

期刊论文

Study of base friction simulation tests based on a complicated engineered bridge slope

Liu HE, Guang WU, Hua WANG

期刊论文

On the improvement design of dynamic characteristics for the roller follower of a variable-speed plate

Hui Ching FAN, Hong Sen YAN

期刊论文

Frequencies of circular plate with concentric ring and elastic edge support

null

期刊论文

Linear ultrasonic motor using quadrate plate transducer

Jiamei JIN, Chunsheng ZHAO

期刊论文

Progressive failure analysis of notched composite plate by utilizing macro mechanics approach

期刊论文

Comprehensive comparison of small-scale natural gas liquefaction processes using brazed plate heat exchangers

Jitan WU, Yonglin JU

期刊论文

Fundamental frequency and testing mode of complicated elastic clamped-plate vibration

QI Hongyuan, GUAN Yiduo

期刊论文

Magnetohydrodynamic slip flow and diffusion of a reactive solute past a permeable flat plate with suction

Krishnendu BHATTACHARYYA, G. C. LAYEK

期刊论文

Effect of size on biaxial flexural strength for cement-based materials by using a triangular plate method

Hakan T TURKER

期刊论文

Base editors: development and applications in biomedicine

期刊论文

Multistage-batch bipolar membrane electrodialysis for base production from high-salinity wastewater

期刊论文

Enzyme@bismuth-ellagic acid: a versatile platform for enzyme immobilization with enhanced acid-base stability

期刊论文