This study examines the temperature field distribution characteristics and temperature effects during the prefabrication of composite box girders with corrugated steel webs(CBGCSWs),aiming to provide practical recomme...This study examines the temperature field distribution characteristics and temperature effects during the prefabrication of composite box girders with corrugated steel webs(CBGCSWs),aiming to provide practical recommendations for controlling temperature-induced cracking and technical guidance for concrete mix proportions and placement processes.Based on field measurement data,a three-dimensional finite element model was developed to simulate the temperature effects at critical locations during the prefabrication phase.By varying the concrete mix proportions,initial casting temperature,and ambient temperature,the study elucidates the variation patterns of the temperature field during precast placement.The results show that the temperature rise caused by hydration heat increases with higher cement and fly ash content,whereas reducing cement and using minimal fly ash effectively lower the hydration temperature.However,the influence of fly ash on prestress losses should be carefully evaluated during the design phase.Higher initial casting temperatures accelerate hydration rates,leading to a rapid temperature rise.Significant differences between the initial casting and ambient temperatures result in larger residual temperature stresses.Based on concrete mix proportions,curing conditions,and ambient temperatures,three recommended casting temperature ranges were identified:5℃–10℃,10℃–25℃,and 25℃–30℃.Variations in the average ambient temperature affect the peak temperature of the hydration reaction and indirectly influence the final temperature distribution of the concrete structure.Optimizing the demolding time and applying geotextiles and water curing effectively reduces the peak temperature,maximum internal-to-surface temperature gradients,and surface tensile stresses,thereby mitigating the risk of temperature-induced cracking.展开更多
Multi-cell structures and corrugated tubes illustrate excellent energy absorption capacities.Besides,bamboo with continuously changing contours demonstrates superior impact-resisting capacities.As a result,a bionic mu...Multi-cell structures and corrugated tubes illustrate excellent energy absorption capacities.Besides,bamboo with continuously changing contours demonstrates superior impact-resisting capacities.As a result,a bionic multi-cell double corrugated(BMDC)tube,inspired by Buddha bamboo,is investigated to assess whether it is an ideal energy absorber candidate.Compared to a corrugated tube,a BMDC contains an outer structure,an inner structure,and diaphragms,which are like webs bridging the inner and outer structures.A basic numerical model is correlated using a physical experiment,followed by an investigation of BMDC tubes’energy absorption performance under axial loading,considering thickness and mass effects.Results indicate that the EA,MCF,and SEA of a BMDC containing 5 diaphragms(BMDC-5)with a 1.5 mm thickness can improve their respective responses by 112.89,112.89,and 83.32%higher compared to a BMDC with no diaphragm(BMDC-0).In addition,the BMDC-5 with 0.156 kg mass generates the highest EA,MCF,and SEA,which is 79.78%higher than a BMDC-0 with the same mass.The parametric analysis illustrates that diaphragms’amplitude and diameter have a decisive influence on energy absorption characteristics.This study emphasizes that BMDC tubes are innovative and practical,possessing excellent energy absorption performance.展开更多
Presetting tensile twins(TTs)can enhance the mechanical properties of magnesium(Mg)alloys.Two as-received(AR)sheets,as-received state-A(AR-A)with fiber texture and nonuniform grains and as-received state-B with basal ...Presetting tensile twins(TTs)can enhance the mechanical properties of magnesium(Mg)alloys.Two as-received(AR)sheets,as-received state-A(AR-A)with fiber texture and nonuniform grains and as-received state-B with basal texture and uniform equiaxial grains are selected to induce TTs via a novel method called corrugated wide limit alignment(CWLA),and the corresponding CWLA-processed sheets are denoted as CWLA-processed state-A(C-A)and CWLA-processed state-B(C-B).The results demonstrate that a larger initial average grain size correlates with a higher fraction of TTs induced in Mg sheets,thereby refining the grains and forming a new rolling direction(RD)tilted texture during CWLA.The ultimate tensile strength increases by 32%from AR-A to C-A,primarily due to refinement strengthening and twinning-induced strain hardening.The recrystallization mechanism of C-A is dominated by twinning-induced dynamic recrystallization(DRX),where DRX grains prefer to inherit the orientation of TTs,resulting in an enhanced RD-tilted texture and the formation of multi-modal texture.The recrystallization mechanism of C-B is mainly discontinuous DRX and continuous DRX,and the DRX grains prefer to inherit the orientation of matrix grains,ultimately forming a basal texture.In summary,the tensile mechanical behavior of pre-twinned Mg sheets significantly depends on the grain size and texture of the AR sheets,so they present similar changing trends during tensile deformation.展开更多
As-rolled titanium/steel composite plate has poor plastic deformation ability,and it is difficult to achieve synergistic deformation,especially for dissimilar metals with very different plastic deformation abilities.T...As-rolled titanium/steel composite plate has poor plastic deformation ability,and it is difficult to achieve synergistic deformation,especially for dissimilar metals with very different plastic deformation abilities.The 304/TC4 composite plate with corrugated interface was manufactured using the asymmetric rolling with local strong stress method.The changing rules of bonding strength and synergistic deformation ability of corrugated interface under different annealing process parameters were studied.The results show that in the range of 550–850℃,especially after the temperature exceeds 650℃,with increasing the annealing temperature and time,the difference of microstructure between peak and trough positions increases,and the bonding strength of the composite plate decreases gradually.Especially,the interfacial bonding strength of the plate sharply decreases at 750℃ due to the rapid growth of intermetallic compounds at the interface and the diffusion holes caused by the difference of element diffusion.The 304/TC4 composite plate has the best synergistic deformation ability when annealing at 650℃/2 h,with the elongation reaching 35%and the tensile strength decreasing to 852 MPa.High interfacial bonding strength and moderate matrix recovery are important prerequisites for synergistic deformation of composite plates.展开更多
The modification design of airfoil is a crucial aspect of aircraft design.Implementing corrugated structures on the lower wing surface can significantly affect the aerodynamic performance of the airfoil under specific...The modification design of airfoil is a crucial aspect of aircraft design.Implementing corrugated structures on the lower wing surface can significantly affect the aerodynamic performance of the airfoil under specific conditions.This study focuses on macroscale corrugated structures based on the Clark YM15 airfoil.A series of concave triangular corrugations were arranged on its lower surface,and various corrugated airfoil types were derived.Computational Fluid Dynamics(CFD)simulations were used to analyze the performance and flow characteristics of these corrugated airfoils,and to investigate the impact of structural parameters,quantity,and layout of the corrugations on the lift-to-drag performance of the airfoil.The results demonstrate that judiciously configured corrugated structures can enhance the lift-to-drag performance at a small angle of attack,with the double-corrugation structure showing the most significant improvement.Wind tunnel experiments were respectively conducted on the double-corrugation airfoil and the original airfoil,which validate the accuracy of the CFD simulations and confirm the lift and drag performance advantages of the corrugated airfoil over the original design.展开更多
Plate heat exchangers suffer from significant energy losses,which adversely affect the overall efficiency of thermal systems.To address this challenge,various heat transfer enhancement techniques have been investigate...Plate heat exchangers suffer from significant energy losses,which adversely affect the overall efficiency of thermal systems.To address this challenge,various heat transfer enhancement techniques have been investigated.Notably,the incorporation of surface corrugations is widely recognized as both effective and practical.Chevron corrugation is the most employed design.However,there remains a need to investigate alternative geometries that may offer superior performance.This study aims to find a novel corrugation design by conducting a comparative CFD analysis of flat,square,chevron,and cylindrical corrugated surfaces,assessing their impact on heat transfer enhancement within a plate heat exchanger.ANSYS Fluent software was used for simulation at four distinct Reynolds numbers(10,000,18,000,26,000,and 28,000),with a heat flux of 12,000 W/m^(2).A structured mesh was generated using Pointwise software.The material of the solid plates was modelled as aluminum,the fluid was modelled as water,and the flow was turbulent.To obtain a fully developed turbulent flow,a separate inlet duct was modelled,and the output velocity profile of the inlet duct was input into the plate heat exchanger.The Nusselt number(Nu)and heattransfer coefficient(h)were calculated to evaluate the performance of all surfaces.The results indicate that cylindrical corrugated surfaces exhibit higher Nusselt numbers than chevron,square,and flat plates.This higher performance is because of the generation of vortices in the middle of the cylindrical texture.Consequently,flow recirculation occurs,leading to reattachment to the mainstreamflow.This phenomenon induces increased turbulence,thereby enhancing the heat transfer efficiency.To validate the results,a grid-convergence independence test was performed for three different mesh sizes.In addition,empirical calculations were performed using the Dittus-Boelter and the Genilaski equations to validate the results of the flat-plate heat exchanger.It was concluded that the cylinder was the best corrugated surface and had a maximum heat transfer 35%higher than that of a flat plate.展开更多
A mathematical model was established for condensation on surfaces of verticalcorrugated plates based on the mechanism of heat transfer enhancement to thin down the liquid filmdue to surface tension effect between corr...A mathematical model was established for condensation on surfaces of verticalcorrugated plates based on the mechanism of heat transfer enhancement to thin down the liquid filmdue to surface tension effect between corrugated plate surfaces and liquid films. The relative heattransfer coefficients of condensation on corrugation plates were calculated in contrast withequivalent vertical plane ones. The heat transfer enhancement effects for the main geometricparameters such as pitch, height, corrugation angle, tilt angle, and fillet radii of corrugationswere analyzed to guide the optimization of corrugation structure for application. A two-scalecorrugation is suggested, which can compromise both the enhanced heat transfer effect and adequatecross section area for flows, and it makes the heat transfer coefficient 1 to 2 times more than thatof an equivalent plane one.展开更多
Corrugated cold roll bonding(CCRB) produces metal composite plate with improved mechanical properties compared with conventional methods,but the interfacial mechanism is not fully understood.Here,Cu/Al composite plate...Corrugated cold roll bonding(CCRB) produces metal composite plate with improved mechanical properties compared with conventional methods,but the interfacial mechanism is not fully understood.Here,Cu/Al composite plate with good plate shape was produced by CCRB,and the bonding mechanism and strength along the corrugated interface were studied by experiments and finite element simulations.The results showed that the average bonding strength of Cu/Al composite plate produced by CCRB was nearly twice that of conventional composite plate at an average reduction of 40% during rolling.Strong friction shear stresses occurred at the interface of the corrugated composite plate,which promoted the plastic deformation of the metals and accelerated the rupture of the brittle interfacial layer.Electron backscattered diffraction analysis showed that higher degrees of grain elongation and refinement occurred in the matrices at the front waist and trough due to the stronger normal and shear stresses.Energy-dispersive spectroscopy line scans showed that the thickest atomic diffusion layer occurred at the front waist.The present combination of experimental and computational analyses provides insights into the underlying mechanism of mechanically improved metal composites prepared by CCRB.展开更多
The corrugated + flat rolling(CFR) and traditional rolling(TR) methods were used to prepare Mg/Al clad plates using AZ31 B Mg and 5052 Al plates, and the interface morphologies and mechanical properties of the resulti...The corrugated + flat rolling(CFR) and traditional rolling(TR) methods were used to prepare Mg/Al clad plates using AZ31 B Mg and 5052 Al plates, and the interface morphologies and mechanical properties of the resulting clad plates were compared. Examination of the microstructures of the plates showed that the TRed Mg/Al clad plate presented a straight interface, while a corrugated interface containing fractured intermetallic particulates was observed for the CFRed plate due to the inhomogeneous strain induced by the corrugated roller. During the CFR process, the corrugated roller can accelerate the rupture of the substrate work-hardening layers and facilitate the mutual extrusion of fresh metals to enhance the interface bonding. Compared with the traditional basal texture of the Mg alloy, the CFR process can change the texture morphology, thereby enhancing the plastic deformation ability of the Mg plate. Tensile tests showed that the CFRed Mg/Al clad plate exhibited a higher ultimate tensile strength(UTS, 316 MPa), which was~ 8% higher than that of the TRed plate(293 MPa). In addition, the bending curve of the CFRed clad plate was smooth and there was no stress sudden drop phenomenon in the bending process. The higher UTS and excellent bending properties of the CFRed clad plate could be attributed to the enhanced coordinated deformation ability of the substrates induced by the corrugated interface, grain refinement, and the change in the Mg alloy texture morphology.展开更多
In this paper,an aluminum corrugated sandwich panel with triangular core under bending loads was investigated.Firstly,the equivalent material parameters of the triangular corrugated core layer,which could be considere...In this paper,an aluminum corrugated sandwich panel with triangular core under bending loads was investigated.Firstly,the equivalent material parameters of the triangular corrugated core layer,which could be considered as an orthotropic panel,were obtained by using Castigliano's theorem and equivalent homogeneous model.Secondly,contributions of the corrugated core layer and two face panels were both considered to compute the equivalent material parameters of the whole structure through the classical lamination theory,and these equivalent material parameters were compared with finite element analysis solutions.Then,based on the Mindlin orthotropic plate theory,this study obtain the closed-form solutions of the displacement for a corrugated sandwich panel under bending loads in specified boundary conditions,and parameters study and comparison by the finite element method were executed simultaneously.展开更多
A series of scaled-model shaking table tests and its simulation analyses using dynamic finite element method were performed to clarify the dynamic behaviors and the seismic stability of embedded corrugated steel culve...A series of scaled-model shaking table tests and its simulation analyses using dynamic finite element method were performed to clarify the dynamic behaviors and the seismic stability of embedded corrugated steel culverts due to strong earth-quakes like the 1995 Hyogoken-nanbu earthquake. The dynamic strains of the embedded culvert models and the seismic soil pressure acting on the models due to sinusoidal and random strong motions were investigated. This study verified that the cor-rugated culvert model was subjected to dynamic horizontal forces (lateral seismic soil pressure) from the surrounding ground, which caused the large bending strains on the structure; and that the structures do not exceed the allowable plastic deformation and do not collapse completely during strong earthquake like Hyogoken-nanbu earthquake. The results obtained are useful for design and construction of embedded long span corrugated steel culverts in seismic regions.展开更多
Corrugated steel web is folded along the longitudinal direction and has the mechanical properties such as axial compression stiffness corrugation effect, shear modulus corrugation effect, similar to that of an accordi...Corrugated steel web is folded along the longitudinal direction and has the mechanical properties such as axial compression stiffness corrugation effect, shear modulus corrugation effect, similar to that of an accordion. In order to study the lateral-torsional buckling of box beams with corrugated steel webs (BBCSW) under the action of bending moment load, the neutral equilibrium equation of BBCSW under the action of bending moment load is derived through the stationary value theory of total potential energy and further, along with taking Kollbrunner-Hajdin correction method and the mechanical properties of the corrugated web into consideration. The analytical calculation formula of lateral-torsional buckling critical bending moment of BBCSW is then obtained. The lateral-torsional buckling critical bending moment of 96 BBCSW test specimens with different geometry dimensions are then calculated using both the analytical calculation method and ANSYS finite element method. The results show that the analytical calculation results agree well with the numerical calculation results using ANSYS, thus proving the accuracy of the analytical calculation method and model simplification hypothesis proposed in this paper. Also, compared with the box beams with flat steel webs (BBFSW) with the same geometry dimensions as BBCSW, within the common range of web space-depth ratio and web span-depth ratio, BBCSW’s lateral-torsional buckling critical bending moment is larger than that of BBFSW. Moreover, the advantages of BBCSW’s stability are even more significant with the increase of web space-depth ratio and web depth-thickness ratio.展开更多
Common compliant joints generally have limited range of motion, reduced fatigue life and high stress concentration. To overcome these shortcomings, periodically corrugated cantilever beam is applied to design complian...Common compliant joints generally have limited range of motion, reduced fatigue life and high stress concentration. To overcome these shortcomings, periodically corrugated cantilever beam is applied to design compliant joints. Basic corrugated beam unit is modeled by using pseudo-rigid-body method. The trajectory and deformation behavior of periodically corrugated cantilever beam are estimated by the transformation of coordinate and superposition of the deformation of corrugated beam units. Finite element analysis（FEA） is carried out on corrugated cantilever beam to estimate the accuracy of the pseudo-rigid-body model. Results show that the kinetostatic behaviors obtained by this method, which has a relative error less than 6%, has good applicability and corrugated cantilever beam has the characteristics of a large range of motion and high mechanical strength. The corrugated cantilever beam is then applied to design a flexible rotational joint to obtain a larger angle output. The paper proposes a pseudo-rigid-body model for corrugated cantilever beam and designed a flexible rotational joint with large angle output.展开更多
The synergistic use of partially encased concrete and composite girders with corrugated steel webs （CGCSWs） has been proposed to avoid the buckling of corrugated steel webs and compression steel flanges under large ...The synergistic use of partially encased concrete and composite girders with corrugated steel webs （CGCSWs） has been proposed to avoid the buckling of corrugated steel webs and compression steel flanges under large combined shear force and bending moment in the hogging area. First, model tests were carried out on two specimens with different shear spans to investigate the mechanical behavior, including the load-carrying capacity, failure modes, flexural and shear stress distribution, and development of concrete cracking. Experimental results show that the interaction of shear force and bending moment causes the failure of specimens. The bending-to-shear ratio does not affect the shear stiffness of a composite girder in the elastic stage when concrete cracking does not exist, but significantly influ- ences the shear stiffness after concrete cracking. In addition, composite sections in the elastic stage sat- isfy the assumption of the plane section under combined shear force and bending moment. However, after concrete cracking in the tension field, the normal stresses of a corrugated web in the tension area become small due to the ＂accordion effect,＂ with almost zero stress at the flat panels but recognizable stress at the inclined panels. Second, three-dimensional finite-element （FE） models considering material and geometric nonlinearity were built and validated by experiments, and parametric analyses were conducted on composite girders with different lengths and heights to determine their load-carrying capacity when subjected to combined loads. Finally, an interaction formula with respect to shear and flexural strength is offered on the basis of experimental and numerical results in order to evaluate the load- carrying capacity of such composite structures, thereby providing a reference for the design of partially encased composite girders with corrugated steel webs （PECGCSWs） under combined flexural and shear loads.展开更多
The dynamics and stability of fluid-conveying corrugated pipes are investigated. The flow velocity is assumed to harmonically vary along the pipe rather than with time. The dimensionless equation is discretized with t...The dynamics and stability of fluid-conveying corrugated pipes are investigated. The flow velocity is assumed to harmonically vary along the pipe rather than with time. The dimensionless equation is discretized with the differential quadrature method (DQM). Subsequently, the effects of the mean flow velocity and two key parameters of the corrugated pipe, i.e., the amplitude of the corrugations and the total number of the corrugations, are studied. The results show that the corrugated pipe will lose stability by flutter even if it has been supported at both ends. When the total number of the corrugations is sufficient, this flutter instability occurs at a micro flow velocity. These phenomena are verified via the Runge-Kutta method. The critical flow velocity of divergence is analyzed in detail. Compared with uniform pipes, the critical velocity will be reduced due to the corrugations, thus accelerating the divergence instability. Specifically, the critical flow velocity decreases if the amplitude of the corrugations increases. However, the critical flow velocity cannot be monotonously reduced with the increase in the total number of the corrugations. An extreme point appears, which can be used to realize the parameter optimization of corrugated pipes in practical applications.展开更多
Three-dimensional numerical computations are conducted to investigate the effects of the blowing ratio and corrugation geometry on the adiabatic film cooling effectiveness as well as the heat transfer coefficient over...Three-dimensional numerical computations are conducted to investigate the effects of the blowing ratio and corrugation geometry on the adiabatic film cooling effectiveness as well as the heat transfer coefficient over a transverse corrugated surface.It is noticeable that the adiabatic wall temperature on the wavy valley of the transverse corrugated surface is relatively lower than that on the wavy peak.Surface corrugation has a relatively obvious influence on the laterallyaveraged adiabatic film cooling effectiveness in the region where the effusion film layer is developed,but has little influence in the front region.Compared to a flat surface,the transverse corrugated surface produces a smaller adiabatic film cooling effectiveness and a higher heat transfer coefficient ratio.The effusion cooling difference between the flat and corrugated surfaces behaves more obviously under a small aspect ratio of the wavy corrugation.展开更多
Ti/Cu/Ti laminated composites were fabricated by corrugated rolling(CR) and flat rolling(FR) method.Microstructure and mechanical properties of CR and FR laminated composites were investigated by scanning electron mic...Ti/Cu/Ti laminated composites were fabricated by corrugated rolling(CR) and flat rolling(FR) method.Microstructure and mechanical properties of CR and FR laminated composites were investigated by scanning electron microscopy, numerical simulation methods, peel and tensile examinations. The effect of CR and FR was comparatively analyzed. The results showed that the CR and FR laminated composites exhibited different effective plastic strain distributions of the Ti layer and Cu layer at the interface. The recrystallization texture, prismatic texture and pyramidal texture were developed in the Ti layer by CR, while the R-Goss texture and shear texture were developed in the Cu layer by CR. The typical deformation texture components were developed in the Ti layer and Cu layer of FR laminated composites. The CR laminated composites had higher bond strength, tensile strength and ductility.展开更多
To figure out the distribution of temperature gradient along the girder height of steel-concrete composite box girder, combined with the mechanical characteristics of prestressed concrete composed box girder with corr...To figure out the distribution of temperature gradient along the girder height of steel-concrete composite box girder, combined with the mechanical characteristics of prestressed concrete composed box girder with corrugated steel webs, the calculation formulas of cross-sectional temperature stress along the span in a simply-supported beam bridge with composite section were derived under the conditions of static equilibrium and deformation compatibility of the beam element. The methods of calculating the maximum temperature stress value were discussed when the connectors are assumed rigid or flexible. Theoretical and numerical results indicate that the method proposed shows better precision for the calculation of temperature self-stress in both the top and the bottom surfaces of the box girder. Moreover, the regularity of temperature stress distribution at different locations along the girder span is that the largest axial force of the top or the bottom plate of the box girder is located in the midspan and spreads decreasingly until zero at both supported ends, and that the greatest longitudinal shear density in steel-concrete interface appears at both supported ends and then reduces gradually to zero in the midspan.展开更多
A variable mass tuned particle absorber is designed for the nonlinear vertical vibration control of the corrugated rolling mill in the composite plate rolling process.Considering the nonlinear damping and nonlinear st...A variable mass tuned particle absorber is designed for the nonlinear vertical vibration control of the corrugated rolling mill in the composite plate rolling process.Considering the nonlinear damping and nonlinear stiffness between the corrugated interface,a three-degree-of-freedom nonlinear vertical vibration mathematical model of corrugated rolling mill based on dynamic vibration absorber control is established.The multi-scale method is used to solve the amplitude–frequency characteristic curve equation of the installed dynamic vibration absorber(DVA)system.The effects of stiffness coefficient and damping coefficient on the amplitude–frequency characteristic curve are analyzed.The expressions of the dynamic developed factor of the corrugated roll are derived,and the influence laws of mass ratio,frequency ratio and damping ratio on the dynamic amplification factor are analyzed.The optimal parameters of the DVA are obtained by adaptive genetic algorithm.The control effect of the DVA on the nonlinear vertical vibration is studied by numerical simulation.The feasibility of the designed dynamic absorber is verified through experiments.The results show that the designed dynamic absorber can effectively suppress the vertical vibration of the corrugated roller.展开更多
Conventional flexible joints generally have limited range of motion and high stress concentration. To overcome these shortcomings, corrugated flexure beam（CF beam） is designed because of its large flexibility obtain...Conventional flexible joints generally have limited range of motion and high stress concentration. To overcome these shortcomings, corrugated flexure beam（CF beam） is designed because of its large flexibility obtained from longer overall length on the same span. The successful design of compliant mechanisms using CF beam requires manipulation of the stiffnesses as the design variables. Empirical equations of the CF beam stiffness components, except of the torsional stiffness, are obtained by curve-fitting method. The application ranges of all the parameters in each empirical equation are also discussed. The ratio of off-axis to axial stiffness is considered as a key characteristic of an effective compliant joint. And parameter study shows that the radius of semi-circular segment and the length of straight segment contribute most to the ratio. At last, CF beam is used to design translational and rotational flexible joints, which also verifies the validity of the empirical equations. CF beam with large flexibility is presented, and empirical equations of its stiffness are proposed to facilitate the design of flexible joint with large range of motion.展开更多
基金supported by the National Natural Science Foundation of China(U22A20598,52279113)Key Research and Development Special Program of Henan Province(241111322500)Support Plan for University Science and Technology Innovation Team of Henan Province(24IRTSTHN009).
文摘This study examines the temperature field distribution characteristics and temperature effects during the prefabrication of composite box girders with corrugated steel webs(CBGCSWs),aiming to provide practical recommendations for controlling temperature-induced cracking and technical guidance for concrete mix proportions and placement processes.Based on field measurement data,a three-dimensional finite element model was developed to simulate the temperature effects at critical locations during the prefabrication phase.By varying the concrete mix proportions,initial casting temperature,and ambient temperature,the study elucidates the variation patterns of the temperature field during precast placement.The results show that the temperature rise caused by hydration heat increases with higher cement and fly ash content,whereas reducing cement and using minimal fly ash effectively lower the hydration temperature.However,the influence of fly ash on prestress losses should be carefully evaluated during the design phase.Higher initial casting temperatures accelerate hydration rates,leading to a rapid temperature rise.Significant differences between the initial casting and ambient temperatures result in larger residual temperature stresses.Based on concrete mix proportions,curing conditions,and ambient temperatures,three recommended casting temperature ranges were identified:5℃–10℃,10℃–25℃,and 25℃–30℃.Variations in the average ambient temperature affect the peak temperature of the hydration reaction and indirectly influence the final temperature distribution of the concrete structure.Optimizing the demolding time and applying geotextiles and water curing effectively reduces the peak temperature,maximum internal-to-surface temperature gradients,and surface tensile stresses,thereby mitigating the risk of temperature-induced cracking.
基金2022 Guangxi University Young and Middle-aged Teachers’Basic Research Ability Improvement Project,2022KY0781,Rui Liang。
文摘Multi-cell structures and corrugated tubes illustrate excellent energy absorption capacities.Besides,bamboo with continuously changing contours demonstrates superior impact-resisting capacities.As a result,a bionic multi-cell double corrugated(BMDC)tube,inspired by Buddha bamboo,is investigated to assess whether it is an ideal energy absorber candidate.Compared to a corrugated tube,a BMDC contains an outer structure,an inner structure,and diaphragms,which are like webs bridging the inner and outer structures.A basic numerical model is correlated using a physical experiment,followed by an investigation of BMDC tubes’energy absorption performance under axial loading,considering thickness and mass effects.Results indicate that the EA,MCF,and SEA of a BMDC containing 5 diaphragms(BMDC-5)with a 1.5 mm thickness can improve their respective responses by 112.89,112.89,and 83.32%higher compared to a BMDC with no diaphragm(BMDC-0).In addition,the BMDC-5 with 0.156 kg mass generates the highest EA,MCF,and SEA,which is 79.78%higher than a BMDC-0 with the same mass.The parametric analysis illustrates that diaphragms’amplitude and diameter have a decisive influence on energy absorption characteristics.This study emphasizes that BMDC tubes are innovative and practical,possessing excellent energy absorption performance.
基金supported by the National Natural Science Foundation of China(No.52005362)the Fundamental Research Program of Shanxi Province(Nos.202303021221005 and 202303021211045)+1 种基金the Patent Commercialization Program of Shanxi Province(No.202402003)the Key Research and Development Plan of Xinzhou City.
文摘Presetting tensile twins(TTs)can enhance the mechanical properties of magnesium(Mg)alloys.Two as-received(AR)sheets,as-received state-A(AR-A)with fiber texture and nonuniform grains and as-received state-B with basal texture and uniform equiaxial grains are selected to induce TTs via a novel method called corrugated wide limit alignment(CWLA),and the corresponding CWLA-processed sheets are denoted as CWLA-processed state-A(C-A)and CWLA-processed state-B(C-B).The results demonstrate that a larger initial average grain size correlates with a higher fraction of TTs induced in Mg sheets,thereby refining the grains and forming a new rolling direction(RD)tilted texture during CWLA.The ultimate tensile strength increases by 32%from AR-A to C-A,primarily due to refinement strengthening and twinning-induced strain hardening.The recrystallization mechanism of C-A is dominated by twinning-induced dynamic recrystallization(DRX),where DRX grains prefer to inherit the orientation of TTs,resulting in an enhanced RD-tilted texture and the formation of multi-modal texture.The recrystallization mechanism of C-B is mainly discontinuous DRX and continuous DRX,and the DRX grains prefer to inherit the orientation of matrix grains,ultimately forming a basal texture.In summary,the tensile mechanical behavior of pre-twinned Mg sheets significantly depends on the grain size and texture of the AR sheets,so they present similar changing trends during tensile deformation.
基金supported by the Major Program of National Natural Science Foundation of China(U22A20188)the Natural Science Foundation of Shanxi Province(202303021224002)+1 种基金the special fund for Science and Technology Innovation Teams of Shanxi Province(202304051001025)the Open Research Fund from the Hai’an and Taiyuan University of Technology Advanced Manufacturing and Intelligent Equipment Industrial Research Institute(2023HA-TYUTKFYF036).
文摘As-rolled titanium/steel composite plate has poor plastic deformation ability,and it is difficult to achieve synergistic deformation,especially for dissimilar metals with very different plastic deformation abilities.The 304/TC4 composite plate with corrugated interface was manufactured using the asymmetric rolling with local strong stress method.The changing rules of bonding strength and synergistic deformation ability of corrugated interface under different annealing process parameters were studied.The results show that in the range of 550–850℃,especially after the temperature exceeds 650℃,with increasing the annealing temperature and time,the difference of microstructure between peak and trough positions increases,and the bonding strength of the composite plate decreases gradually.Especially,the interfacial bonding strength of the plate sharply decreases at 750℃ due to the rapid growth of intermetallic compounds at the interface and the diffusion holes caused by the difference of element diffusion.The 304/TC4 composite plate has the best synergistic deformation ability when annealing at 650℃/2 h,with the elongation reaching 35%and the tensile strength decreasing to 852 MPa.High interfacial bonding strength and moderate matrix recovery are important prerequisites for synergistic deformation of composite plates.
基金supported by the 2023 Shanghai Industrial Collaborative Innovation Project,China(No.CXXT-2023-05).
文摘The modification design of airfoil is a crucial aspect of aircraft design.Implementing corrugated structures on the lower wing surface can significantly affect the aerodynamic performance of the airfoil under specific conditions.This study focuses on macroscale corrugated structures based on the Clark YM15 airfoil.A series of concave triangular corrugations were arranged on its lower surface,and various corrugated airfoil types were derived.Computational Fluid Dynamics(CFD)simulations were used to analyze the performance and flow characteristics of these corrugated airfoils,and to investigate the impact of structural parameters,quantity,and layout of the corrugations on the lift-to-drag performance of the airfoil.The results demonstrate that judiciously configured corrugated structures can enhance the lift-to-drag performance at a small angle of attack,with the double-corrugation structure showing the most significant improvement.Wind tunnel experiments were respectively conducted on the double-corrugation airfoil and the original airfoil,which validate the accuracy of the CFD simulations and confirm the lift and drag performance advantages of the corrugated airfoil over the original design.
文摘Plate heat exchangers suffer from significant energy losses,which adversely affect the overall efficiency of thermal systems.To address this challenge,various heat transfer enhancement techniques have been investigated.Notably,the incorporation of surface corrugations is widely recognized as both effective and practical.Chevron corrugation is the most employed design.However,there remains a need to investigate alternative geometries that may offer superior performance.This study aims to find a novel corrugation design by conducting a comparative CFD analysis of flat,square,chevron,and cylindrical corrugated surfaces,assessing their impact on heat transfer enhancement within a plate heat exchanger.ANSYS Fluent software was used for simulation at four distinct Reynolds numbers(10,000,18,000,26,000,and 28,000),with a heat flux of 12,000 W/m^(2).A structured mesh was generated using Pointwise software.The material of the solid plates was modelled as aluminum,the fluid was modelled as water,and the flow was turbulent.To obtain a fully developed turbulent flow,a separate inlet duct was modelled,and the output velocity profile of the inlet duct was input into the plate heat exchanger.The Nusselt number(Nu)and heattransfer coefficient(h)were calculated to evaluate the performance of all surfaces.The results indicate that cylindrical corrugated surfaces exhibit higher Nusselt numbers than chevron,square,and flat plates.This higher performance is because of the generation of vortices in the middle of the cylindrical texture.Consequently,flow recirculation occurs,leading to reattachment to the mainstreamflow.This phenomenon induces increased turbulence,thereby enhancing the heat transfer efficiency.To validate the results,a grid-convergence independence test was performed for three different mesh sizes.In addition,empirical calculations were performed using the Dittus-Boelter and the Genilaski equations to validate the results of the flat-plate heat exchanger.It was concluded that the cylinder was the best corrugated surface and had a maximum heat transfer 35%higher than that of a flat plate.
文摘A mathematical model was established for condensation on surfaces of verticalcorrugated plates based on the mechanism of heat transfer enhancement to thin down the liquid filmdue to surface tension effect between corrugated plate surfaces and liquid films. The relative heattransfer coefficients of condensation on corrugation plates were calculated in contrast withequivalent vertical plane ones. The heat transfer enhancement effects for the main geometricparameters such as pitch, height, corrugation angle, tilt angle, and fillet radii of corrugationswere analyzed to guide the optimization of corrugation structure for application. A two-scalecorrugation is suggested, which can compromise both the enhanced heat transfer effect and adequatecross section area for flows, and it makes the heat transfer coefficient 1 to 2 times more than thatof an equivalent plane one.
基金financially supported by the Major Program of National Natural Science Foundation of China (No. U1710254)Shanxi Province Science and Technology Major Projects (No.20181101008)+1 种基金the Scientific and Technological Progress of Shanxi Province Colleges and Universities (No.2017132)the National Natural Science Foundation of China (Nos.51974196, 51975398,and 51905372)。
文摘Corrugated cold roll bonding(CCRB) produces metal composite plate with improved mechanical properties compared with conventional methods,but the interfacial mechanism is not fully understood.Here,Cu/Al composite plate with good plate shape was produced by CCRB,and the bonding mechanism and strength along the corrugated interface were studied by experiments and finite element simulations.The results showed that the average bonding strength of Cu/Al composite plate produced by CCRB was nearly twice that of conventional composite plate at an average reduction of 40% during rolling.Strong friction shear stresses occurred at the interface of the corrugated composite plate,which promoted the plastic deformation of the metals and accelerated the rupture of the brittle interfacial layer.Electron backscattered diffraction analysis showed that higher degrees of grain elongation and refinement occurred in the matrices at the front waist and trough due to the stronger normal and shear stresses.Energy-dispersive spectroscopy line scans showed that the thickest atomic diffusion layer occurred at the front waist.The present combination of experimental and computational analyses provides insights into the underlying mechanism of mechanically improved metal composites prepared by CCRB.
基金financially supported by the National Natural Science Foundation of China(Nos.U1710254,51904205,51904206)Science and Technology Foundation of State Key laboratory(No.6142909180205)+4 种基金Taiyuan City Science and Technology Major Projects(No.170203)Shanxi Province Science and Technology Major Projects(Nos.MC2016-01,20181101008)the Natural Science Foundation of Shanxi Province(Nos.201801D221221,201801D221130 and 201801D221346)Key Projects of Shanxi Province Key Research and Development Plan(No.201703D111003)the China Postdoctoral Science Foundation(Nos.2018M641680,2018M641681)。
文摘The corrugated + flat rolling(CFR) and traditional rolling(TR) methods were used to prepare Mg/Al clad plates using AZ31 B Mg and 5052 Al plates, and the interface morphologies and mechanical properties of the resulting clad plates were compared. Examination of the microstructures of the plates showed that the TRed Mg/Al clad plate presented a straight interface, while a corrugated interface containing fractured intermetallic particulates was observed for the CFRed plate due to the inhomogeneous strain induced by the corrugated roller. During the CFR process, the corrugated roller can accelerate the rupture of the substrate work-hardening layers and facilitate the mutual extrusion of fresh metals to enhance the interface bonding. Compared with the traditional basal texture of the Mg alloy, the CFR process can change the texture morphology, thereby enhancing the plastic deformation ability of the Mg plate. Tensile tests showed that the CFRed Mg/Al clad plate exhibited a higher ultimate tensile strength(UTS, 316 MPa), which was~ 8% higher than that of the TRed plate(293 MPa). In addition, the bending curve of the CFRed clad plate was smooth and there was no stress sudden drop phenomenon in the bending process. The higher UTS and excellent bending properties of the CFRed clad plate could be attributed to the enhanced coordinated deformation ability of the substrates induced by the corrugated interface, grain refinement, and the change in the Mg alloy texture morphology.
基金the National Natural Science Foundation of China(Grant 11572122)the Scientific Research Foundation of Huaihua University(Grant HHUY2017-02)+2 种基金111 Project(Grant B16015)Stake Key Laboratory of Mechanical Structural Strength and Vibration(Grant SV2017-KF-20)Joint Centre for Intelligent New Energy Vehicle.
文摘In this paper,an aluminum corrugated sandwich panel with triangular core under bending loads was investigated.Firstly,the equivalent material parameters of the triangular corrugated core layer,which could be considered as an orthotropic panel,were obtained by using Castigliano's theorem and equivalent homogeneous model.Secondly,contributions of the corrugated core layer and two face panels were both considered to compute the equivalent material parameters of the whole structure through the classical lamination theory,and these equivalent material parameters were compared with finite element analysis solutions.Then,based on the Mindlin orthotropic plate theory,this study obtain the closed-form solutions of the displacement for a corrugated sandwich panel under bending loads in specified boundary conditions,and parameters study and comparison by the finite element method were executed simultaneously.
文摘A series of scaled-model shaking table tests and its simulation analyses using dynamic finite element method were performed to clarify the dynamic behaviors and the seismic stability of embedded corrugated steel culverts due to strong earth-quakes like the 1995 Hyogoken-nanbu earthquake. The dynamic strains of the embedded culvert models and the seismic soil pressure acting on the models due to sinusoidal and random strong motions were investigated. This study verified that the cor-rugated culvert model was subjected to dynamic horizontal forces (lateral seismic soil pressure) from the surrounding ground, which caused the large bending strains on the structure; and that the structures do not exceed the allowable plastic deformation and do not collapse completely during strong earthquake like Hyogoken-nanbu earthquake. The results obtained are useful for design and construction of embedded long span corrugated steel culverts in seismic regions.
基金Projects(51408449,51778630)supported by the National Natural Science Foundation of ChinaProject(2018zzts189)supported by the Fundamental Research Funds for the Central Universities,China
文摘Corrugated steel web is folded along the longitudinal direction and has the mechanical properties such as axial compression stiffness corrugation effect, shear modulus corrugation effect, similar to that of an accordion. In order to study the lateral-torsional buckling of box beams with corrugated steel webs (BBCSW) under the action of bending moment load, the neutral equilibrium equation of BBCSW under the action of bending moment load is derived through the stationary value theory of total potential energy and further, along with taking Kollbrunner-Hajdin correction method and the mechanical properties of the corrugated web into consideration. The analytical calculation formula of lateral-torsional buckling critical bending moment of BBCSW is then obtained. The lateral-torsional buckling critical bending moment of 96 BBCSW test specimens with different geometry dimensions are then calculated using both the analytical calculation method and ANSYS finite element method. The results show that the analytical calculation results agree well with the numerical calculation results using ANSYS, thus proving the accuracy of the analytical calculation method and model simplification hypothesis proposed in this paper. Also, compared with the box beams with flat steel webs (BBFSW) with the same geometry dimensions as BBCSW, within the common range of web space-depth ratio and web span-depth ratio, BBCSW’s lateral-torsional buckling critical bending moment is larger than that of BBFSW. Moreover, the advantages of BBCSW’s stability are even more significant with the increase of web space-depth ratio and web depth-thickness ratio.
基金supported by National Natural Science Foundation of China(Grant Nos.51205134,91223201)Doctoral Fund of Ministry of Education of China(Grant No.20120172120001)+2 种基金Research Project of State Key Laboratory of Mechanical System and Vibration of China(Grant No.MSV201405)Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(GDUPS,2010)Fundamental Research Funds for the Central Universities(Grant No.2013ZM012)
文摘Common compliant joints generally have limited range of motion, reduced fatigue life and high stress concentration. To overcome these shortcomings, periodically corrugated cantilever beam is applied to design compliant joints. Basic corrugated beam unit is modeled by using pseudo-rigid-body method. The trajectory and deformation behavior of periodically corrugated cantilever beam are estimated by the transformation of coordinate and superposition of the deformation of corrugated beam units. Finite element analysis（FEA） is carried out on corrugated cantilever beam to estimate the accuracy of the pseudo-rigid-body model. Results show that the kinetostatic behaviors obtained by this method, which has a relative error less than 6%, has good applicability and corrugated cantilever beam has the characteristics of a large range of motion and high mechanical strength. The corrugated cantilever beam is then applied to design a flexible rotational joint to obtain a larger angle output. The paper proposes a pseudo-rigid-body model for corrugated cantilever beam and designed a flexible rotational joint with large angle output.
基金The authors gratefully thank the National Natural Science Foundation of China （51308070, 51408070, and 51378080）, the National Basic Research Program of China （2015CB057702）, the Key Discipline Fund of Creative Project of Bridge and Tunnel Engineering （13ZDXK04） from the Changsha University of Science and Technology, the Open Fund of the Hunan Province University Key Laboratory of Bridge Engineering （13KA04）, and the Applied Basic Research Program of Shanxi Province for their support,
文摘The synergistic use of partially encased concrete and composite girders with corrugated steel webs （CGCSWs） has been proposed to avoid the buckling of corrugated steel webs and compression steel flanges under large combined shear force and bending moment in the hogging area. First, model tests were carried out on two specimens with different shear spans to investigate the mechanical behavior, including the load-carrying capacity, failure modes, flexural and shear stress distribution, and development of concrete cracking. Experimental results show that the interaction of shear force and bending moment causes the failure of specimens. The bending-to-shear ratio does not affect the shear stiffness of a composite girder in the elastic stage when concrete cracking does not exist, but significantly influ- ences the shear stiffness after concrete cracking. In addition, composite sections in the elastic stage sat- isfy the assumption of the plane section under combined shear force and bending moment. However, after concrete cracking in the tension field, the normal stresses of a corrugated web in the tension area become small due to the ＂accordion effect,＂ with almost zero stress at the flat panels but recognizable stress at the inclined panels. Second, three-dimensional finite-element （FE） models considering material and geometric nonlinearity were built and validated by experiments, and parametric analyses were conducted on composite girders with different lengths and heights to determine their load-carrying capacity when subjected to combined loads. Finally, an interaction formula with respect to shear and flexural strength is offered on the basis of experimental and numerical results in order to evaluate the load- carrying capacity of such composite structures, thereby providing a reference for the design of partially encased composite girders with corrugated steel webs （PECGCSWs） under combined flexural and shear loads.
基金Project supported by the National Natural Science Foundation of China(Nos.11872044,11702192,and 11672187)the National Key Research and Development Program of China(No.2018YFB0106200)
文摘The dynamics and stability of fluid-conveying corrugated pipes are investigated. The flow velocity is assumed to harmonically vary along the pipe rather than with time. The dimensionless equation is discretized with the differential quadrature method (DQM). Subsequently, the effects of the mean flow velocity and two key parameters of the corrugated pipe, i.e., the amplitude of the corrugations and the total number of the corrugations, are studied. The results show that the corrugated pipe will lose stability by flutter even if it has been supported at both ends. When the total number of the corrugations is sufficient, this flutter instability occurs at a micro flow velocity. These phenomena are verified via the Runge-Kutta method. The critical flow velocity of divergence is analyzed in detail. Compared with uniform pipes, the critical velocity will be reduced due to the corrugations, thus accelerating the divergence instability. Specifically, the critical flow velocity decreases if the amplitude of the corrugations increases. However, the critical flow velocity cannot be monotonously reduced with the increase in the total number of the corrugations. An extreme point appears, which can be used to realize the parameter optimization of corrugated pipes in practical applications.
文摘Three-dimensional numerical computations are conducted to investigate the effects of the blowing ratio and corrugation geometry on the adiabatic film cooling effectiveness as well as the heat transfer coefficient over a transverse corrugated surface.It is noticeable that the adiabatic wall temperature on the wavy valley of the transverse corrugated surface is relatively lower than that on the wavy peak.Surface corrugation has a relatively obvious influence on the laterallyaveraged adiabatic film cooling effectiveness in the region where the effusion film layer is developed,but has little influence in the front region.Compared to a flat surface,the transverse corrugated surface produces a smaller adiabatic film cooling effectiveness and a higher heat transfer coefficient ratio.The effusion cooling difference between the flat and corrugated surfaces behaves more obviously under a small aspect ratio of the wavy corrugation.
基金financially supported by the National Key R&D Program of China (No.2018YFA0707300)the Natural Science Foundation of Shanxi Province,China (No.201801D221131)+2 种基金the National Natural Science Foundation of China (Nos.51905372,51904206,51805359,52075359)Shanxi Province Science and Technology Major Project,China (No.20181102011)China Postdoctoral Science Foundation (No.2020M670705)。
文摘Ti/Cu/Ti laminated composites were fabricated by corrugated rolling(CR) and flat rolling(FR) method.Microstructure and mechanical properties of CR and FR laminated composites were investigated by scanning electron microscopy, numerical simulation methods, peel and tensile examinations. The effect of CR and FR was comparatively analyzed. The results showed that the CR and FR laminated composites exhibited different effective plastic strain distributions of the Ti layer and Cu layer at the interface. The recrystallization texture, prismatic texture and pyramidal texture were developed in the Ti layer by CR, while the R-Goss texture and shear texture were developed in the Cu layer by CR. The typical deformation texture components were developed in the Ti layer and Cu layer of FR laminated composites. The CR laminated composites had higher bond strength, tensile strength and ductility.
基金Supported by National Natural Science Foundation of China (No. 50978105)
文摘To figure out the distribution of temperature gradient along the girder height of steel-concrete composite box girder, combined with the mechanical characteristics of prestressed concrete composed box girder with corrugated steel webs, the calculation formulas of cross-sectional temperature stress along the span in a simply-supported beam bridge with composite section were derived under the conditions of static equilibrium and deformation compatibility of the beam element. The methods of calculating the maximum temperature stress value were discussed when the connectors are assumed rigid or flexible. Theoretical and numerical results indicate that the method proposed shows better precision for the calculation of temperature self-stress in both the top and the bottom surfaces of the box girder. Moreover, the regularity of temperature stress distribution at different locations along the girder span is that the largest axial force of the top or the bottom plate of the box girder is located in the midspan and spreads decreasingly until zero at both supported ends, and that the greatest longitudinal shear density in steel-concrete interface appears at both supported ends and then reduces gradually to zero in the midspan.
基金National Key Research and Development Project(2018YFA0707300)National Natural Science Foundation of China(52205404)Fundamental Research Program of Shanxi Province(202203021212293).
文摘A variable mass tuned particle absorber is designed for the nonlinear vertical vibration control of the corrugated rolling mill in the composite plate rolling process.Considering the nonlinear damping and nonlinear stiffness between the corrugated interface,a three-degree-of-freedom nonlinear vertical vibration mathematical model of corrugated rolling mill based on dynamic vibration absorber control is established.The multi-scale method is used to solve the amplitude–frequency characteristic curve equation of the installed dynamic vibration absorber(DVA)system.The effects of stiffness coefficient and damping coefficient on the amplitude–frequency characteristic curve are analyzed.The expressions of the dynamic developed factor of the corrugated roll are derived,and the influence laws of mass ratio,frequency ratio and damping ratio on the dynamic amplification factor are analyzed.The optimal parameters of the DVA are obtained by adaptive genetic algorithm.The control effect of the DVA on the nonlinear vertical vibration is studied by numerical simulation.The feasibility of the designed dynamic absorber is verified through experiments.The results show that the designed dynamic absorber can effectively suppress the vertical vibration of the corrugated roller.
基金Supported by National Natural Science Foundation of China(Grant Nos.51205134,91223201)Doctoral Fund of Ministry of Education of China(Grant No.20120172120001)Research Project of State Key Laboratory of Mechanical System and Vibration,China(Grant No.MSV201405)
文摘Conventional flexible joints generally have limited range of motion and high stress concentration. To overcome these shortcomings, corrugated flexure beam（CF beam） is designed because of its large flexibility obtained from longer overall length on the same span. The successful design of compliant mechanisms using CF beam requires manipulation of the stiffnesses as the design variables. Empirical equations of the CF beam stiffness components, except of the torsional stiffness, are obtained by curve-fitting method. The application ranges of all the parameters in each empirical equation are also discussed. The ratio of off-axis to axial stiffness is considered as a key characteristic of an effective compliant joint. And parameter study shows that the radius of semi-circular segment and the length of straight segment contribute most to the ratio. At last, CF beam is used to design translational and rotational flexible joints, which also verifies the validity of the empirical equations. CF beam with large flexibility is presented, and empirical equations of its stiffness are proposed to facilitate the design of flexible joint with large range of motion.
