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Frontiers of Structural and Civil Engineering 2022年第1期16卷 131-143页

作者： Mohammad R.IRSHIDAT Rami S.AL-HUSBAN Department of Civil Engineering Jordan University of Science and TechnologyIrbid 22110Jordan

This paper studied the effect of incorporation of carbon nanotubes(CNTs)in carbon fiber reinforced polymer(CFRP)on strengthening of reinforced concrete(RC)beams.The RC beams were prepared,strengthened in flexure by externally bonded CFRP or CNTs-modified CFRP sheets,and tested under four-point loading.The experimental results showed the ability of the CNTs to delay the initiation of the cracks and to enhance the flexural capacity of the beams strengthened with CFRP.A nonlinear finite element(FE)model was built,validated,and used to study the effect of various parameters on the strengthening efficiency of CNTs-modified CFRP.The studied parameters included concrete strength,flexural reinforcement ratio,and CFRP sheet configuration.The numerical results showed that utilization of CNTs in CFRP production improved the flexural capacity of the strengthened beams for U-shape and underside-strip configurations.The enhancement was more pronounced in the case of U-shape than in the case of use of sheet strip covers on the underside of the beam.In case of using underside-strip,the longer or the wider the sheet,the higher was the flexural capacity of the beams.The flexural enhancement of RC beams by strengthening with CNTs-modified CFRP decreased with increasing the rebar diameter and was not affected by concrete strength.

关键词： RC beams flexural strengthening CFRP CNTs finite element

Piezoelectric-AIN resonators at two-dimensional flexural modes for the density and viscosity decoupled determination of liquids

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Microsystems & Nanoengineering 2022年第2期8卷 23-34页

作者： Linya Huang Wei Li Guoxi Luo Dejiang Lu Libo Zhao Ping Yang Xiaozhang Wang Jiuhong Wang Qijing Lin Zhuangde Jiang State Key Laboratory for Manufacturing Systems Engineering International Joint Laboratory for Micro/Nano Manufacturing and Measurement TechnologiesOverseas Expertise Introduction Center for Micro/Nano Manufacturing and Nano Measurement Technologies Discipline InnovationXi'an Jiaotong University(Yantai)Research Institute for Intelligent Sensing Technology and SystemXi'an Jiaotong UniversityXi'an 710049China School of Mechanical Engineering Xi'an Jiaotong UniversityXi'an 710049China The Eleventh Research Institute of The Sixth Academy of CASC Xi'an 710100China

A micromachined resonator immersed in liquid provides valuable resonance parameters for determining the fluidic parameters.However,the liquid operating environment poses a challenge to maintaining a fine sensing performance,particularly through electrical characterization.This paper presents a piezoelectric micromachined cantilever with a stepped shape for liquid monitoring purposes.Multiple modes of the proposed cantilever are available with full electrical characterization for realizing self-actuated and seif-sensing capabilities.The focus is on higher flexural resonances,which nonconventionally feature two-dimensional vibration modes.Modal analyses are conducted for the developed cantilever under flexural vibrations at different orders.Modeling explains not only the basic length-dominant mode but also higher modes that simultaneously depend on the length and width of the cantilever.This study determines that the analytical predictions for resonant frequency in liquid media exhibit good agreement with the experimental results.Furthermore,the experiments on cantilever resonators are performed in various test liquids,demonstrating that higher-order flexural modes allow for the decoupled measurements of density and viscosity.The measurement differences achieve 0.39%in density and 3.50%in viscosity,and the frequency instability is below 0.05%o.On the basis of these results,design guidelines for piezoelectric higher-mode resonators are proposed for liquid sensing.

关键词： flexural cantilever viscosity

flexural Wave Bandgap Property of a Periodic Pipe with Axial Load and Hydro-Pressure

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Acta Mechanica Solida Sinica 2019年第2期32卷 173-185页

作者： Jiangwei Liu Dianlong Yu Zhenfang Zhang Huijie Shen Jihong Wen Vibration and Acoustics Research Group Laboratory of Science and Technology on Integrated Logistics Support College of Mechatronics Engineering and Automation National University of Defense Technology Changsha 410073 China College of Power Engineering Naval University of Engineering Wuhan 430033 China

A periodical composite material pipe is proposed based on the Bragg scattering mechanism of phononic crystals (PCs). The band gap (BG) properties of the flexural wave in this PC pipe under axial load and hydro-pressure are calculated using the transfer matrix (TM) method. The frequency response functions (FRFs) of the PC pipe under axial load and hydro-pressure are calculated using the finite element approach, and the mechanism is elucidated to illustrate the phenomenon. The results show that axial load and hydro-pressure and their combination all have a great influence on the flexural vibration proper ties. This research offers theoretical support for research on PC pipes with complex conditions and is of great significance in solving the problem of high pressure.

关键词： Phononic crystals flexural vibration properties Axial load Hydro-pressure

flexural strength of fused filament fabricated (FFF) PLA parts on an open-source 3D printer

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Advances in Manufacturing 2018年第4期6卷 430-441页

作者： Shilpesh R. Rajpurohit Harshit K. Dave Department of Mechanical Engineering SV National Institute of Technology Surat Gujarat 395007 India

Fused filament fabrication (FFF) has been widely used to develop prototypes as well as functional parts owing to its capability for creating parts with complex geometries in a short time without the specific requirement of tooling. The mechanical properties of parts produced by FFF exhibit 70%-80% of the mechanical properties of parts produced by injection molding. The mechanical properties of FFF-produced parts are primarily dependent on the selection of various process variables. The mechanical properties of the part can be enhanced through the proper selection of process variables. In the present experimental investigation, the effects of the process variables, viz. raster angle, layer height, and raster width on the flexural properties of FFF-printed polylactic acid (PLA) is studied. The result shows that flexural strength is primarily influenced by layer height followed by raster angle. The sample printed with 100-μm layer height and 0° raster angle exhibits a higher tensile strength. Further, the microscopic examination of the deformed specimen is performed to understand the mode of failure. Specimens printed at different raster angles show different modes of failure.

关键词： Fused filament fabrication (FFF) Polylactic acid (PLA) Raster angle Layer height Raster width flexural strength

flexural Property of String Beam of Pre-Stressed Glulam Based on Influence of Regulation and Control

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Structural Durability & Health Monitoring 2019年第2期13卷 143-179页

作者： Nan Guo Wenbo Wang Hongliang Zuo School of Civil Engineering Northeast Forestry UniversityHarbin150040China

Applying pre-stress in glulam beam can reduce its deformation and make full use of the compressive strength of wood.However,when the glulam with low strength and the pre-stressed steel with high strength form combined members,materials of high strength can’t be fully utilized.Therefore,this study puts forward the idea of regulating and controlling string beam of pre-stressed glulam.By regulating and controlling the pre-stress,a part of the load borne by the wood is allocated to the pre-stressed tendon,which is equivalent to completing a redistribution of internal force,thus realizing the repeated utilization of the wood strength and the full utilization of the strength of the high-strength pre-stressed tendon.The bending experiments of 10 beams under 5 working conditions are carried out.The failure mode,bearing capacity and deformation of the beams are analyzed.The results show that 90%of beams are deformed under compression.The ultimate load of the regulated and controlled beam is obviously larger than that of the unregulated beam,and the ultimate load of the beam increases with the increase of the degree of regulation and control.Compared with that of the unregulated beams,the ultimate load of beams regulated by 7.5%-30%increases by 25.42%-65.08%,and the regulated and controlled effect is obvious.With the increase of the regulation and control amplitude of pre-stress,the stiffness of string beam of pre-stressed glulam increases.In addition,with the increase of the regulation and control amplitude,the compression height of the beam increases before the failure,and it reaches the state of full-section compression at the time of failure,giving full play to the compressive property of the glulam.At the end of the experiment,the constitutive relation which can reflect the anisotropy of the wood is established combined with the experimental data.The finite element analysis of the beam under 7 working conditions is carried out by using ABAQUS finite element program,and the influence of the regulation and control ampli

关键词： String beam of glulam flexural property experimental study pre-stress regulation and control

Intra-trench variations in flexural bending of the subducting Pacific Plate along the Tonga-Kermadec Trench

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Acta Oceanologica Sinica 2019年第11期38卷 81-90页

作者： Fan Zhang Jian Lin Zhiyuan Zhou Key Laboratory of Ocean and Marginal Sea Geology South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China Department of Geology and Geophysics Woods Hole Oceanographic InstitutionWoods HoleMA 02543USA Innovation Academy of South China Sea Ecology and Environmental Engineering Chinese Academy of SciencesGuangzhou 510301China

We conducted a detailed analysis of along-trench variations in the flexural bending of the subducting Pacific Plate at the Tonga-Kermadec Trench.Inversions were conducted to obtain best-fitting solutions of trench-axis loadings and variations in the effective elastic plate thickness for the analyzed flexural bending profiles.Results of the analyses revealed significant along-trench variations in plate flexural bending:the trench relief(W0)of 1.9 to 5.1 km;trench-axis vertical loading(V0)of-0.5×10^12 to 2.2×10^12 N/m;axial bending moment(M0)of 0.1×10^17 to 2.2×10^17 N;effective elastic plate thickness seaward of the outer-rise region(Te^M)of 20 to 65 km,trench-ward of the outer-rise(Te^M)of 11 to 33 km,and the transition distance(Xr)of 20 to 95 km.The Horizon Deep,the second greatest trench depth in the world,has the greatest trench relief(W0 of 5.1km)and trench-axis loading(V0 of 2.2×10^12N/m);these values are only slightly smaller than that of the Challenger Deep(W0 of 5.7km and V0 of 2.9×10^12N/m)and similar to that of the Sirena Deep(W0 of 5.2 km and V0 of 2.0×10^12 N/m)of the Mariana Trench,suggesting that these deeps are linked to great flexural bending of the subducting plates.Analyses using three independent methods,i.e.,the/inversion,the flexural curvature/yield strength envelope analysis,and the elasto-plastic bending model with normal faults,all yielded similar average Te reduction of 28%-36% and average Te reduction area S△Te of 1195-1402 km^2 near the trench axis.The calculated brittle yield zone depth from the flexural curvature/yield strength envelope analysis is also consistent with the distribution of the observed normal faulting earthquakes.Comparisons of the Manila,Philippine,Tonga-Kermadec,Japan,and Mariana Trenches revealed that the average values Te^M of Te^M and both in general increase with the subducting plate age.

关键词： Tonga-Kermadec Trench horizon deep axial vertical force axial bending moment effective elastic thickness flexural curvature analysis

Effects of Prestressing of the Ring Gear in Interference Fit on flexural Fatigue Strength of Tooth Root

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Chinese Journal of Mechanical Engineering 2019年第4期32卷 85-93页

作者： Shiping Yang Yixing Ji Yulin Mo Tianyu Xia School of Mechanical Engineering Xiangtan University

When the gearbox body interference is connected to the ring gear, prestressing occurs in the ring gear, which has a significant impact on the strength and life of the gear. Research on the prestressing of the inner ring gear is in the preliminary stage, and the distribution rule of the prestressing and the influence of each parameter on the interference prestressing have not been derived. In this paper, based on the method of calculating the prestressing of the thick cylinder in interference fit, the ring gear is found to be equivalent to a thick cylinder, and the distribution rule of prestressing of the ring gear in the interference fit is inferred. Then, by modeling and analyzing the gearbox body and ring gear in the interference fit using ABAQUS, the distribution rule of prestressing the ring gear in the interference fit is obtained through a numerical simulation. Finally, the prestressing of the ring gear in the interference fit is measured using X-ray di raction, and the distribution rule of prestressing of the ring gear in the interference fit is obtained through analysis. Compared with the distribution rule of prestressing in theory, numerical simulation, and experiment, the theoretical distribution rule of prestressing is amended through a statistical method, and a more accurate formula of prestressing is obtained. Through the calculation of the stress and bending moment in the dangerous section of the ring gear through prestressing, the formula for checking the tooth root flexural fatigue strength in the interference fit prestressing is inferred. This research proposes a tooth root bending strength conditional formula for the inner ring gear of the interference fit, which serves as a guide for the design and production of the actual interference joint inner ring gear.

关键词： Interference fit Ring gear Prestressing,Tooth root flexural fatigue strength X-ray diffraction (XRD)

Experimental study on flexural behavior of ECC/RC composite beams with U-shaped ECO permanent formwork

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Frontiers of Structural and Civil Engineering 2019年第5期13卷 1271-1287页

作者： Zhi QIAO Zuanfeng PAN Weichen XUE Shaoping MENG Key Laboratory of Concrete & Prestressed Concrete Structures of the Ministry of Education Southeast UniversityNanjing 210096China College of Civil Engineering Tongji UniversityShanghai 200092China School of Civil Engineering Southeast UniversityNanjing 210096China

To enhance the durability of a reinforced concrete structure, engineered cementitious composite (ECC), which exhibits high tensile ductility and good crack control ability, is considered a promising alternative to conventional concrete. However, broad application of ECC is hindered by its high cost. This paper presents a new means to address this issue by introducing a composite beam with a U-shaped ECC permanent formwork and infill concrete. The flexural performance of the ECC/RC composite beam has been investigated experimentally with eight specimens. According to the test results, the failure of a composite beam with a U-shaped ECC formwork is initiated by the crushing of compressive concrete rather than debonding, even if the surface between the ECC and the concrete is smooth as-finished. Under the same reinforcement configurations, ECC/RC composite beams exhibit increases in flexural performance in terms of ductility, load-carrying capacity, and damage tolerance compared with the counterpart ordinary RC beam. Furthermore, a theoretical model based on the strip method is proposed to predict the moment-curvature responses of ECC/RC composite beams, and a simplified method based on the equivalent rectangular stress distribution approach has also evolved. The theoretical results are found to be in good agreement with the test data.

关键词： engineered cementitious composite (ECC) durability ECC/RC composite beam permanent formwork flexural performance theoretical method

flexural Capacity Formula of Diaphragm-Through Joints of Concrete-Filled Square Steel Tubular Columns

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Transactions of Tianjin University 2017年第3期23卷 258-266页

作者： Bin Rong Rui Liu Zhenyu Li Changxi Feng Guangchao You Fafitis Apostolos School of Civil Engineering Tianjin UniversityTianjin 300072China Key Laboratory of Coast Civil Structure Safety Ministry of EducationTianjin 300072China Department of Civil and Environmental Engineering Arizona State UniversityTempe 85287USA

Finite element analysis and parametric studies were performed to investigate the flexural capacity of the panel zone of diaphragm-through joints between concretefilled square steel tubular columns and H-shaped steel beams.Through the comparisons of failure modes,load–displacement curves,and bearing capacity,it was found that the flexural capacity of the panel zone of diaphragmthrough joints was determined by the tensile action and influence of the web of H-shaped steel beams,and the axial load should be taken into account.The steel tube and the diaphragm were the major parts of the joint that resisted the bending moment.The contribution of in-filled concrete had little influence on the flexural capacity of the panel zone of the joint and could be neglected.According to the results of these numerical studies,a formula that considered the influence of the web of H-shaped steel beams and the axial load was developed based on the yield lines in the diaphragm and the steel tube.The results of the proposed formula were in good agreement with the numerical data of this investigation.

关键词： Diaphragm-through joint H-shaped steel beam flexural capacity Finite element analysis Yield line

Theoretical analysis and experimental investigation on flexural performance of steel reinforced ultrahigh toughness cementitious composite (RUHTCC) beams

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Science China(Technological Sciences) 2009年第4期52卷 1068-1089页

作者： XU ShiLang ZHANG XiuFang State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China

UHTCC (ultrahigh toughness cementitious composite), which is a kind of ultrahigh toughness cemen- titious composites material, exhibits pseudo strain hardening feature when subjected to tension load, and has enormous ductility and prominent crack dispersal ability. Accordingly, UHTCC can improve mechanical behavior of ordinary concrete structure especially its durability, and has been regarded as historical breakthrough to traditional cementitious materials. In this paper, the study focuses on flexure behavior of steel reinforced beam made of UHTCC. Based on the plane section assumption, along with two equilibrium equations of force and moment, the formulae to calculate the flexural load capability for the reinforced ultrahigh toughness cementitious composite (RUHTCC) beam were developed under the assumption that the compression stress- strain relationship in the UHTCC material is a bilinear model. Following this, the simplified formulae were further evolved by effective rectangle stress distribution approach in order to facilitate design of practical engineering. Two effective parameters introduced in effective rectangle approach were determined. The mathematical expressions to evaluate limited rein- forcement ratio, flexural stiffness as well as ductility index were proposed, too. Last, two series of dif- ferent reinforcement ratios of the RUHTCC beams were tested in four-point flexure loading. For com- parison purposes, ordinary RC (reinforced concrete) beams also were prepared. Both moment curva- ture curves and load mid-span displacement curves were recorded and compared with the theoretical calculations. A good agreement between them was found, which validates the proposed theoretical formulae. For ductility index, a slightly big difference between the experimental values and the calcu- lated ones exists. The experimental results show that, compared to control RC beams, the RUHTCC beam can improve both flexural capacity and ductility index, and the degree of improvement will de- crease with the increase in

关键词： ultrahigh toughness cementitious composites (UHTCC) RUHTCC beam flexural capacity crack width ductility index reinforcement ratio