This study involved a comprehensive investigation aimed at achieving efficient multi-millijoule THz wave generation by exploiting the unique properties of cylindrical GaAs waveguides as effective mediators of the conv...This study involved a comprehensive investigation aimed at achieving efficient multi-millijoule THz wave generation by exploiting the unique properties of cylindrical GaAs waveguides as effective mediators of the conversion of laser energy into THz waves.Through meticulous investigation,valuable insights into optimizing THz generation processes for practical applications were unearthed.By investigating Hertz potentials,an eigen-value equation for the solutions of the guided modes(i.e.,eigenvalues)was found.The effects of various param-eters,including the effective mode index and the laser pulse power,on the electric field components of THz radia-tion,including the fundamental TE(transverse electric)and TM(transverse magnetic)modes,were evaluated.By analyzing these factors,this research elucidated the nuanced mechanisms governing THz wave generation within cylindrical GaAs waveguides,paving the way for refined methodologies and enhanced efficiency.The sig-nificance of cylindrical GaAs waveguides extends beyond their roles as mere facilitators of THz generation;their design and fabrication hold the key to unlocking the potential for compact and portable THz systems.This trans-formative capability not only amplifies the efficiency of THz generation but also broadens the horizons of practical applications.展开更多
Steel cylindrical shells are widely used in engineering structures due to their high strength-to-weight ratio,but they are vulnerable to buckling under axial loads.To address this limitation,fiber-reinforced polymer(F...Steel cylindrical shells are widely used in engineering structures due to their high strength-to-weight ratio,but they are vulnerable to buckling under axial loads.To address this limitation,fiber-reinforced polymer(FRP)composites have emerged as promising materials for structural reinforcement.This study investigates the buckling behavior of steel cylindrical shells reinforced with inner and outer layers of polymer composite materials under axial compression.Using analytical and numerical modeling methods,the critical buckling loads for different reinforcement options were evaluated.Two-sided glass fiber reinforced plastic(GFRP)or carbon fiber reinforced plastic(CFRP)coatings,as well as combined coatings with layers of different composites,were considered.GFRP+CFRPIn the calculations,the coatings were treated as homogeneous orthotropic materials with equivalent averaged elastic characteristics.The numerical analysis revealed that CFRP reinforcement achieved the highest increase in buckling load,with improvements ranging from 9.84%to 47.29%,depending on the composite thickness and steel shell thickness.GFRP reinforcement,while beneficial,demonstrated a lower effectiveness,with buckling load increases between 5.89%and 19.30%.The hybrid reinforcement provided an optimal balance,improving buckling resistance by GFRP+CFRP6.94%to 43.95%.Statistical analysis further identified composite type and thickness as the most significant factors affecting buckling performance.The findings suggest that CFRP is the preferred reinforcement material,especially when applied to thin-walled cylindrical shells,while hybrid reinforcements can be effectively utilized for structures requiring a balance between stiffness and ductility.These insights provide a foundation for optimizing FRP reinforcement strategies to enhance the structural integrity of steel shells in engineering applications.展开更多
Magnesium alloy thin-walled cylindrical components with the advantages of high specific stiffness and strength present broad prospect for the lightweight of aerospace components.However,poor formability resulting from...Magnesium alloy thin-walled cylindrical components with the advantages of high specific stiffness and strength present broad prospect for the lightweight of aerospace components.However,poor formability resulting from the hexagonal close-packed crystal structure in magnesium alloy puts forwards a great challenge for thin-walled cylindrical components fabrication,especially for extreme structure with the thicknesschanging web and the high thin-wall.In this research,an ZK61 magnesium alloy thin-walled cylindrical component was successfully fabricated by two-step forging,i.e.,the pre-forging and final-forging is mainly used for wed and thin-wall formation,respectively.Microstructure and mechanical properties at the core,middle and margin of the web and the thin-wall of the pre-forged and final-forged components are studied in detail.Due to the large strain-effectiveness and metal flow along the radial direction(RD),the grains of the web are all elongated along RD for the pre-forged component,where an increasingly elongated trend is found from the core to the margin of the wed.A relatively low recrystallized degree occurs during pre-forging,and the web at different positions are all with prismatic and pyramid textures.During finalforging,the microstructures of the web and the thin-wall are almost equiaxed due to the remarkable occurrence of dynamic recrystallization.Similarity,except for few basal texture of the thin-wall,only prismatic and pyramid textures are found for the final-forged component.Compared with the initial billet,an obviously improved mechanical isotropy is achieved during pre-forging,which is well-maintained during final-forging.展开更多
Owing to eccentricity and inclination, circularity of a cylindrical workpiece cannot be measured precisely by a circularity measuring machine when the workpiece has a small dimension(diameter ≤ 3 mm). In this paper, ...Owing to eccentricity and inclination, circularity of a cylindrical workpiece cannot be measured precisely by a circularity measuring machine when the workpiece has a small dimension(diameter ≤ 3 mm). In this paper, with the aim of solving this problem, circularity metrology of a small cylindrical workpiece using a segmenting scanning method is analyzed. The cross-sectional circle of the cylinder is segmented into several equivalent arcs for measurement by a two-dimensional coordinate measuring machine(profilometer). The circularity contour is obtained by stitching together arc contours obtained by data processing of the coordinates. Different segmenting patterns for coordinate scanning are considered. Measurement results are presented for three segmentation patterns, with 8, 10, and 12 equal segments, respectively.These results are evaluated in terms of the matching coefficient between neighboring arc contours on circumferential stitching, the Euclidean distance between neighboring arc contours on radial stitching, and the curvature of the arcs. From these evaluations, it is found that as the number of segments is increased, the matching coefficient increases from 0.14 to 0.50, the Euclidean distance decreases from 32 nm to 26 nm,and the curvature becomes close to the standard value.展开更多
The worm wheel whose undercutting characteristic is researched is a member of offsetting normal arc-toothed cylindrical worm drive.The tooth profile of the worm in its offsetting normal section is a circular arc.The n...The worm wheel whose undercutting characteristic is researched is a member of offsetting normal arc-toothed cylindrical worm drive.The tooth profile of the worm in its offsetting normal section is a circular arc.The normal vector used to calculate the first-type limit function is determined in the natural frame without the aid of the curvature parameter of worm helicoid.The first-type limit line is ascertained via solving the nonlinear equations iteratively.It is discovered that one first-type limit line exists on the tooth surface of worm wheel by numerical simulation,and such a line is normally located out of the meshing zone.Only one intersection point exists between the first and second-types of limit lines,and this point is a lubrication weak point.The undercutting mechanism is essentially that a part of the meshing zone near the conjugated line of worm tooth crest will come into the undercutting area and will be cut off during machining the worm wheel.The machining simulation verifies the correctness of undercutting mechanism.Moreover,a convenient and practical characteristic quantity is proposed to judge whether the undercutting exists in the whole meshing zone via computing the first-type limit function values on the worm tooth crest.展开更多
The propagation of solitary waves in fiber-reinforced hyperelastic cylindrical shells holds tremendous potential for structural health monitoring.However,solitary waves under external forces are unstable,and may break...The propagation of solitary waves in fiber-reinforced hyperelastic cylindrical shells holds tremendous potential for structural health monitoring.However,solitary waves under external forces are unstable,and may break then cause chaos in severe cases.In this paper,the stability of solitary waves and chaos suppression in fiber-reinforced compressible hyperelastic cylindrical shells are investigated,and sufficient conditions for chaos generation as well as chaos suppression in cylindrical shells are provided.Under the radial periodic load and structural damping,the traveling wave equation describing the single radial symmetric motion of the cylindrical shell is obtained by using the variational principle and traveling wave method.By employing the bifurcation theory of dynamical systems,the parameter space for the appearance of peak solitary waves,valley solitary waves,and periodic waves in an undisturbed system is determined.The sufficient conditions for chaos generation are derived by the Melnikov method.It is found that the disturbed system leads to chaotic motions in the form of period-doubling bifurcation.Furthermore,a second weak periodic disturbance is applied as the non-feedback control input to suppress chaos,and the initial phase difference serves as the control parameter.According to the Melnikov function,the sufficient conditions for the second excitation amplitude and initial phase difference to suppress chaos are determined.The chaotic motions can be successfully converted to some regular motions by weak periodic perturbations.The results of theoretical analyses are compared with numerical simulation,and they are in good agreement.This paper extends the research scope of nonlinear elastic dynamics,and provides a strategy for controlling chaotic responses of hyperelastic structures.展开更多
The effects of a harmonically exciting monopole source on an infinitely long cylindrical cavity embedded entirely within a fluid-saturated poroelastic formation of infinite extent are examined theoretically.It is assu...The effects of a harmonically exciting monopole source on an infinitely long cylindrical cavity embedded entirely within a fluid-saturated poroelastic formation of infinite extent are examined theoretically.It is assumed that the source is located outside the cavity at a specified distance from the borehole axis.The magnitudes of the hoop and radial stresses beside the pore pressures exerted on the interface and inside the porous medium surrounding the borehole are calculated and discussed.Biot's poroelastic modeling along with three types of boundary conditions for the cylindrical interface including the ideal fluid,empty borehole,and rigid inclusion with a hard boundary is employed for the analysis.Utilizing a proper translational addition theorem for expressing the incident spherical wave in terms of cylindrical wave expansions,the proposed boundary conditions at the interface are satisfied.Stresses are formulated by means of wave potential functions in a three-dimensional(3D)manner.The effects of the frequency and the radial distance between the source and borehole on the induced stresses are examined for the first cylindrical modes over frequency spectra.Two permeability conditions for the interface and three types of soils for the porous formation are considered throughout the analysis.To give an overall outline of the study,a numerical example is presented.The results clearly indicate that the distance is a key parameter and has considerable effects on the induced stress values.In addition,the interface permeability condition and soil characteristics play an important role in determining the dynamic response of the borehole.Finally,the obtained results are compared with the relevant analyses existing in the literature for some limit cases,and good agreement is achieved.展开更多
To address the problems of low accuracy by the CONWEP model and poor efficiency by the Coupled Eulerian-Lagrangian(CEL)method in predicting close-range air blast loads of cylindrical charges,a neural network-based sim...To address the problems of low accuracy by the CONWEP model and poor efficiency by the Coupled Eulerian-Lagrangian(CEL)method in predicting close-range air blast loads of cylindrical charges,a neural network-based simulation(NNS)method with higher accuracy and better efficiency was proposed.The NNS method consisted of three main steps.First,the parameters of blast loads,including the peak pressures and impulses of cylindrical charges with different aspect ratios(L/D)at different stand-off distances and incident angles were obtained by two-dimensional numerical simulations.Subsequently,incident shape factors of cylindrical charges with arbitrary aspect ratios were predicted by a neural network.Finally,reflected shape factors were derived and implemented into the subroutine of the ABAQUS code to modify the CONWEP model,including modifications of impulse and overpressure.The reliability of the proposed NNS method was verified by related experimental results.Remarkable accuracy improvement was acquired by the proposed NNS method compared with the unmodified CONWEP model.Moreover,huge efficiency superiority was obtained by the proposed NNS method compared with the CEL method.The proposed NNS method showed good accuracy when the scaled distance was greater than 0.2 m/kg^(1/3).It should be noted that there is no need to generate a new dataset again since the blast loads satisfy the similarity law,and the proposed NNS method can be directly used to simulate the blast loads generated by different cylindrical charges.The proposed NNS method with high efficiency and accuracy can be used as an effective method to analyze the dynamic response of structures under blast loads,and it has significant application prospects in designing protective structures.展开更多
This paper theoretically investigates the influence of a cylindrical PN junction on the propagation characteristics of shear cylindrical waves(SCWs)in an infinitely long piezoelectric semiconductor(PS)concentric cylin...This paper theoretically investigates the influence of a cylindrical PN junction on the propagation characteristics of shear cylindrical waves(SCWs)in an infinitely long piezoelectric semiconductor(PS)concentric cylinder structure.This PS concentric cylinder structure is composed of three regions:an inner PS cylinder,an outer PS cylindrical shell,and a cylindrical PN junction at the interface between the two aforementioned regions.First,the basic equations of the PS concentric cylinder structure are derived,taking into account the coupling of the mechanical displacement,electric potential,and charge carrier perturbation in the cylindrical coordinate system.Next,a mathematical model for the SCWs in this PS concentric cylinder structure is established,utilizing the spectral method and considering the physical characteristics of the cylindrical PN junction.Finally,the dispersion and attenuation curves of the SCWs are numerically calculated to discuss the influence of the interface effect resulting from the cylindrical PN junction.It is found that the existence of a cylindrical PN junction can either reduce or enhance the mechanical-to-electrical energy conversion,which is closely related to the doping mode,doping concentration,and curvature radius of the cylindrical interface.A reasonable design of the aforementioned parameters can optimize the wave motion in acoustic equipment formed by PS media with different frequencies or wavelengths.The construction and resolution of the mathematical model as well as the analysis of physical mechanisms can offer theoretical guidance for improving the efficiency of energy conversion from mechanical energy to electrical energy and optimizing the acoustic performance of energy harvesting devices.展开更多
Thermal conductivity is an important physical parameter in thermal equipment,in the blast furnace,rotary kiln and other equipment,multi-layer cylindrical wall is extremely important in industrial production of a therm...Thermal conductivity is an important physical parameter in thermal equipment,in the blast furnace,rotary kiln and other equipment,multi-layer cylindrical wall is extremely important in industrial production of a thermal conductivity model,its thermal conductivity coefficient determines the ability of the cylindrical wall,which results in the existence of a large number of multi-layer cylinder thermal conductivity problems of the pitfalls.This paper focuses on the establishment of a mathematical model of the multi-layer cylinder thermal conductivity problem,by applying different voltages to the multi-layer cylinder wall,study the temperature distribution of the multi-layer cylinder wall under the conditions of natural convection and forced convection,and draw the line graphs under the conditions of natural convection and forced convection by Origin software,and finally conclude that:under the same conditions,the forced convection is significantly stronger than the natural convection;under the conditions of different voltages,the multi-layer cylinder wall under the conditions of steady state convection,the forced convection is much stronger than natural convection.Under different voltage conditions,the temperature of the multilayer cylinder wall under steady state conditions increases with the increase of voltage,which provides a strong support for the related research.展开更多
Most of the existing studies on tunnel blast wave are based on spherical or grouped charges, however,conventional weapons are mostly cylindrical rather than spherical. In order to analyze the impact of cylindrical cha...Most of the existing studies on tunnel blast wave are based on spherical or grouped charges, however,conventional weapons are mostly cylindrical rather than spherical. In order to analyze the impact of cylindrical charges on the tunnel blast wave loads and to develop a quantitative calculation method, this study carried out experimental and numerical research. Initially, external explosion experiments were conducted using both 35 kg spherical charges and cylindrical charges with aspect ratio of 4.8 at two different distances from the tunnel entrance. Comparative analysis of the blast wave parameters in the tunnel revealed that the explosive equivalent of the cylindrical charges was significantly higher than that of the spherical charges. To address this, an equivalent coefficient κ based on the spherical charges was proposed for the cylindrical charges. Subsequently, numerical simulations were conducted for the experimental conditions, and the numerical simulation results match the experiments well. Through numerical calculations, the reliability of the equivalent coefficient κ under the experimental conditions was verified, and comparison analysis indicated that the explosion energy of cylindrical charges spreads more radially, resulting in more explosion energy entering the tunnel, which is the fundamental reason for the increase in tunnel blast wave loads. Additionally, analyzing the explosion energy ratio entering the tunnel is an effective method for calculating the equivalent coefficient κ. Finally, through more than one hundred sets of numerical calculation results, the impact of the proportional distance λ and the ratio of charge mass to the tunnel cross-section dimension φ on the equivalence coefficients κ was investigated. An empirical formula for the equivalence coefficient κ was derived through fitting, and the accuracy of the formula was validated through literature experimental results. The research findings of this paper will provide valuable guidance for the calculation of blast wave loads in tunnel.展开更多
The fixed-setting face-milled curvilinear cylindrical gear features teeth that are arc-shaped along the longitudinal direction.Some researchers hypothesize that this arc-tooth may enhance the lubrication conditions of...The fixed-setting face-milled curvilinear cylindrical gear features teeth that are arc-shaped along the longitudinal direction.Some researchers hypothesize that this arc-tooth may enhance the lubrication conditions of the gear.This study focuses on this type of gear,employing both finite element analysis(FEA)and analytical methods to determine the input parameters required for elastohydrodynamic lubrication(EHL)analysis.The effects of assembly errors,tooth surface modifications,load,and face-milling cutter radius on the lubrication performance of these gears are systematically investigated.The finite element model(FEM)of the gear pair is utilized to calculate the coordinates of contact points on the tooth surface and the corresponding contact pressures at the tooth surface nodes throughout a meshing cycle.Subsequently,the normal load on specific gear teeth is determined using a gradient-based approach.Entrainment speed,slip-to-roll ratio,and effective radius near the contact points on the tooth surface are derived through analytical methods.The data obtained from FEA serve as input parameters for EHL simulations.The lubrication performance of the curvilinear cylindrical gear is evaluated through example studies.The findings indicate that using FEA to provide input parameters for EHL simulations can reveal the occurrence of edge contact phenomena during gear meshing,allowing for a more accurate representation of the gear’s lubrication conditions.The lubrication performance of the curvilinear cylindrical gear is shown to be independent of the face-milling cutter radius but is significantly influenced by the size of the contact pattern on the tooth surface.Curvilinear gears with larger contact patterns demonstrate superior lubrication performance.展开更多
Waveform regulator in charge is a method that can realize multi-source detonation wave superposition through a single point detonation.The method does not need to weaken the strength of shell,and relies on the high st...Waveform regulator in charge is a method that can realize multi-source detonation wave superposition through a single point detonation.The method does not need to weaken the strength of shell,and relies on the high stress generated by superposition to cut shell into regular fragments.Additionally,it can be combined with different initiation methods to alter the fragmentation outcomes.In this study,aiming at the fracture strain of metal cylindrical shell driven by explosive charge with waveform regulator,theoretical analysis was first adopted to obtain the prediction model of the fracture strain of cylindrical shell with waveform regulator and the model of the axial distribution of the stress concentration factor.On this basis,both theoretical analysis and numerical models were utilized to investigate the effect of waveform regulator on the initial velocity of fragments.Finally,experiments were conducted to validate the fracture strain prediction model for cylindrical shell with waveform regulator.The research results show that the collision angles of the detonation waves at different axial positions are different,which leads to the stress concentration factor on the shell presenting a trend of gradually decreasing,then sharply increasing,and then rapidly decreasing along the axial direction.Additionally,the changes in the slot spacing and the thickness of outer charge will also affect the stress concentration factor,and the influence of outer charge thickness is relatively large.The smaller the ratio of charge volume to waveform regulator volume,the larger the axial sparse wave intensity and the more the fragment initial velocity decrease.From the initiation end to the non-initiation end,the failure modes of the shell sequentially change from pure shear,to mixed tensile-shear,and finally to pure tensile failure.The experimental results are in good agreement with the calculated results of the fracture strain model,and the maximum relative error is less than 10%,which indicates that the fracture strain prediction model of the cylindrical shell with waveform regulator established in this paper by considering the increase of elastic energy per unit volume caused by stress concentration on the shell is reliable.展开更多
In recent years,magneto-electro-elastic(MEE)cylindrical shells with step-wise thicknesses have shown significant potential in the field of vibration energy harvesting.To aid the design of such energy harvesting device...In recent years,magneto-electro-elastic(MEE)cylindrical shells with step-wise thicknesses have shown significant potential in the field of vibration energy harvesting.To aid the design of such energy harvesting devices,an accurate free vibration analysis of embedded MEE cylindrical shells with step-wise thicknesses is performed within the framework of symplectic mechanics.By using the Legendre transformation,a new known vector is defined to transform the higher-order partial differential governing equations into a set of lower-order ordinary differential equations.Therefore,the original vibration analysis is regarded as an eigen problem in the symplectic space,and analytical solutions can be represented by the symplectic series.In numerical examples,the new analytical solutions are compared with the existing results,and good agreement is observed.Furthermore,the effects of critical design parameters on free vibration characteristics are thoroughly investigated.All numerical results can serve as benchmarks for the development of other approximate or numerical methods.展开更多
The nonlinear traveling wave vibration of rotating ferromagnetic functionally graded(FG)cylindrical shells under multi-physics fields is investigated.Grounded in the Kirchhoff-Love thin shell theory,the geometric nonl...The nonlinear traveling wave vibration of rotating ferromagnetic functionally graded(FG)cylindrical shells under multi-physics fields is investigated.Grounded in the Kirchhoff-Love thin shell theory,the geometric nonlinearity is incorporated into the model,and the constitutive equations are derived.The physical parameters of functionally graded materials(FGMs),which exhibit continuous variation across the thickness gradient,are of particular interest.The nonlinear magneto-thermoelastic governing equations are derived in accord with Hamilton's principle.The nonlinear partial differential equations are discretized with the Galerkin method,and the analytical expression of traveling wave frequencies is derived with an approximate method.The accuracy of the proposed method is validated through the comparison with the results from the literature and numerical solutions.Finally,the visualization analyses are conducted to examine the effects of key parameters on the traveling wave frequencies.The results show that the factors including the power-law index,temperature,magnetic field intensity,and rotating speed have the coupling effects with respect to the nonlinear vibration behavior.展开更多
The multi-layer cylindrical helicoidal fiber structure(MCHFS)exists widely in biological materials such as bone and wood at the microscale.MCHFSs typically function as reinforcing elements to enhance the toughness of ...The multi-layer cylindrical helicoidal fiber structure(MCHFS)exists widely in biological materials such as bone and wood at the microscale.MCHFSs typically function as reinforcing elements to enhance the toughness of materials.In this study,we establish a shear lag-based pullout model of the cylindrical helicoidal fiber(CHF)for investigating interlayer stress transfer and debonding behaviors,with implications regarding the underlying toughening mechanism of MCHFS.Based on the shear lag assumptions,analytical solutions for the stress and displacement fields of the MCHFS during the pullout are derived by considering the CHF as a cylindrically monoclinic material and verified through the 3D finite element simulation.It is found that the helical winding of CHF results in both axial and hoop interlayer shear stresses.Both the helical winding angle and the elastic moduli of the fiber and matrix have significant influences on interlayer stress transfer.This work reveals a new interlayer stress transfer mechanism in the MCHFS existing widely in biological materials.展开更多
To explore the wide-frequency damping and vibration-attenuation performances in the application of aerospace components,the cylindrical sandwich shell structure with a gradient core of entangled wire mesh was proposed...To explore the wide-frequency damping and vibration-attenuation performances in the application of aerospace components,the cylindrical sandwich shell structure with a gradient core of entangled wire mesh was proposed in this paper.Firstly,the gradient cores of entangled wire mesh in the axial and radial directions were prepared by using an in-house Numerical Control weaving machine,and the metallurgical connection between skin sheets and the gradient core was performed using vacuum brazing.Secondly,to investigate the mechanical properties of cylindrical sandwich shells with axial or radial gradient cores,quasi-static and dynamic mechanical experiments were carried out.The primary evaluations of mechanical properties include secant stiffness,natural frequency,Specific Energy Absorption(SEA),vibration acceleration level,and so on.The results suggest that the vibration-attenuation performance of the sandwich shell is remarkable when the high-density core layer is at the end of the shell or abuts the inner skin.The axial gradient material has almost no influence on the vibration frequencies of the shell,whereas the vibration frequencies increase dramatically when the high-density core layer approaches the skin.Moreover,compared to the conventional sandwich shells,the proposed functional grading cylindrical sandwich shell exhibits more potential in mass reduction,stiffness designing,and energy dissipation.展开更多
Shot peening is commonly employed for surface deformation strengthening of cylindrical surface part.Therefore,it is critical to understand the effects of shot peening on residual stress and surface topography.Compared...Shot peening is commonly employed for surface deformation strengthening of cylindrical surface part.Therefore,it is critical to understand the effects of shot peening on residual stress and surface topography.Compared to flat surface,cylindrical surface shot peening has two significant features:(i)the curvature of the cylindrical surface and the scattering of the shot stream cause dis-tributed impact velocities;(i)the rotation of the part results in a periodic variation of the impact velocity component.Therefore,it is a challenge to quickly and accurately predict the shot peening residual stress and surface topography of cylindrical surface.This paper developed a high-precision model which considers the more realistic shot peening process.Firstly,a kinematic analysis model was developed to simulate the relative movement of numerous shots and cylindrical surface.Then,the spatial distribution and time-varying impact information was calculated.Subsequently,the impact information was used for finite element modeling to predict residual stress and surface topography.The proposed kinematic analysis method was validated by comparison with the dis-crete element method.Meanwhile,9310 high strength steel rollers shot peening test verified the effectiveness of the model in predicting the residual stress and surface topography.In addition,the effects of air pressure and attack angle on the residual stress and surface topography were investigated.This work could provide a functional package for efficient prediction of the surface integrity and guide industrial application in cylindrical surface shot peening.展开更多
Mechanical-guided assembly of three-dimensional(3D)mesostructures from pre-defined 2D precursors based on the deterministically controlled buckling has attracted increasing attention in both fundamental and applied re...Mechanical-guided assembly of three-dimensional(3D)mesostructures from pre-defined 2D precursors based on the deterministically controlled buckling has attracted increasing attention in both fundamental and applied research areas,owing to the compelling advantages in developing flexible electronic devices with complex 3D geometries and novel functions.Recently,a buckling-guided strategy was reported to enable assembly of complex 3D mesostructures and electronic devices on cylindrical and cylinder-like substrates,which can be integrated with vascular systems for monitoring of flow rate and other physical signals.A clear understanding of nonlinear buckling deformations of elastic beams assembled on cylindrical substrates is thereby essential for the relevant structural design.In this work,we present a systematic study on the nonlinear deformations of buckled ribbon-type structures on cylindrical substrates.Two representative classes of ribbon-type structures are considered,including arc structures and serpentine structures.Starting with the finite-deformation beam theory,a theoretical model is established to investigate deformed configurations resulted from the controlled buckling,including ribbons assembled on both outer and inner surfaces of the substrate.The structure-substrate contact and self-contact are taken into account in the analyses,which could lead to distinct deformed configurations.Both experimental studies and finite element analyses(FEA)were carried out to validate the developed theoretical model.A demonstrative device design based on the 3D ribbon network outside the cylindrical substrate suggests potential applications in energy harvesting across a broad range of frequency.The theoretical model presented herein could offer insights for the practical design of 3D electronic devices that can be conformally integrated with curvy biological surfaces.展开更多
The sloshing in a group of rigid cylindrical tanks with baffles and on soil foundation under horizontal excitation is studied analytically.The solutions for the velocity potential are derived out by the liquid subdoma...The sloshing in a group of rigid cylindrical tanks with baffles and on soil foundation under horizontal excitation is studied analytically.The solutions for the velocity potential are derived out by the liquid subdomain method.Equivalent models with mass-spring oscillators are established to replace continuous fluid.Combined with the least square technique,Chebyshev polynomials are employed to fit horizontal,rocking and horizontal-rocking coupling impedances of soil,respectively.A lumped parameter model for impedance is presented to describe the effects of soil on tank structures.A mechanical model for the soil-foundation-tank-liquid-baffle system with small amount of calculation and high accuracy is proposed using the substructure technique.The analytical solutions are in comparison with data from reported literature and numerical codes to validate the effectiveness and correctness of the model.Detailed dynamic properties and seismic responses of the soil-tank system are given for the baffle number,size and location as well as soil parameter.展开更多
文摘This study involved a comprehensive investigation aimed at achieving efficient multi-millijoule THz wave generation by exploiting the unique properties of cylindrical GaAs waveguides as effective mediators of the conversion of laser energy into THz waves.Through meticulous investigation,valuable insights into optimizing THz generation processes for practical applications were unearthed.By investigating Hertz potentials,an eigen-value equation for the solutions of the guided modes(i.e.,eigenvalues)was found.The effects of various param-eters,including the effective mode index and the laser pulse power,on the electric field components of THz radia-tion,including the fundamental TE(transverse electric)and TM(transverse magnetic)modes,were evaluated.By analyzing these factors,this research elucidated the nuanced mechanisms governing THz wave generation within cylindrical GaAs waveguides,paving the way for refined methodologies and enhanced efficiency.The sig-nificance of cylindrical GaAs waveguides extends beyond their roles as mere facilitators of THz generation;their design and fabrication hold the key to unlocking the potential for compact and portable THz systems.This trans-formative capability not only amplifies the efficiency of THz generation but also broadens the horizons of practical applications.
文摘Steel cylindrical shells are widely used in engineering structures due to their high strength-to-weight ratio,but they are vulnerable to buckling under axial loads.To address this limitation,fiber-reinforced polymer(FRP)composites have emerged as promising materials for structural reinforcement.This study investigates the buckling behavior of steel cylindrical shells reinforced with inner and outer layers of polymer composite materials under axial compression.Using analytical and numerical modeling methods,the critical buckling loads for different reinforcement options were evaluated.Two-sided glass fiber reinforced plastic(GFRP)or carbon fiber reinforced plastic(CFRP)coatings,as well as combined coatings with layers of different composites,were considered.GFRP+CFRPIn the calculations,the coatings were treated as homogeneous orthotropic materials with equivalent averaged elastic characteristics.The numerical analysis revealed that CFRP reinforcement achieved the highest increase in buckling load,with improvements ranging from 9.84%to 47.29%,depending on the composite thickness and steel shell thickness.GFRP reinforcement,while beneficial,demonstrated a lower effectiveness,with buckling load increases between 5.89%and 19.30%.The hybrid reinforcement provided an optimal balance,improving buckling resistance by GFRP+CFRP6.94%to 43.95%.Statistical analysis further identified composite type and thickness as the most significant factors affecting buckling performance.The findings suggest that CFRP is the preferred reinforcement material,especially when applied to thin-walled cylindrical shells,while hybrid reinforcements can be effectively utilized for structures requiring a balance between stiffness and ductility.These insights provide a foundation for optimizing FRP reinforcement strategies to enhance the structural integrity of steel shells in engineering applications.
基金supported by the National Natural Science Foundation of China(No.52405408,No.U21A20131,No.U2037204,No.52422510)the Natural Science Foundation of Hubei Province(No.2023AFB116)+1 种基金the State Key Laboratory of Materials Processing and Die&Mould TechnologyHuazhong University of Science and Technology(No.P2022-005)。
文摘Magnesium alloy thin-walled cylindrical components with the advantages of high specific stiffness and strength present broad prospect for the lightweight of aerospace components.However,poor formability resulting from the hexagonal close-packed crystal structure in magnesium alloy puts forwards a great challenge for thin-walled cylindrical components fabrication,especially for extreme structure with the thicknesschanging web and the high thin-wall.In this research,an ZK61 magnesium alloy thin-walled cylindrical component was successfully fabricated by two-step forging,i.e.,the pre-forging and final-forging is mainly used for wed and thin-wall formation,respectively.Microstructure and mechanical properties at the core,middle and margin of the web and the thin-wall of the pre-forged and final-forged components are studied in detail.Due to the large strain-effectiveness and metal flow along the radial direction(RD),the grains of the web are all elongated along RD for the pre-forged component,where an increasingly elongated trend is found from the core to the margin of the wed.A relatively low recrystallized degree occurs during pre-forging,and the web at different positions are all with prismatic and pyramid textures.During finalforging,the microstructures of the web and the thin-wall are almost equiaxed due to the remarkable occurrence of dynamic recrystallization.Similarity,except for few basal texture of the thin-wall,only prismatic and pyramid textures are found for the final-forged component.Compared with the initial billet,an obviously improved mechanical isotropy is achieved during pre-forging,which is well-maintained during final-forging.
基金supported by the National Defense Basic Scientific Research Program of China(Grant No.JCKY2019427D002).
文摘Owing to eccentricity and inclination, circularity of a cylindrical workpiece cannot be measured precisely by a circularity measuring machine when the workpiece has a small dimension(diameter ≤ 3 mm). In this paper, with the aim of solving this problem, circularity metrology of a small cylindrical workpiece using a segmenting scanning method is analyzed. The cross-sectional circle of the cylinder is segmented into several equivalent arcs for measurement by a two-dimensional coordinate measuring machine(profilometer). The circularity contour is obtained by stitching together arc contours obtained by data processing of the coordinates. Different segmenting patterns for coordinate scanning are considered. Measurement results are presented for three segmentation patterns, with 8, 10, and 12 equal segments, respectively.These results are evaluated in terms of the matching coefficient between neighboring arc contours on circumferential stitching, the Euclidean distance between neighboring arc contours on radial stitching, and the curvature of the arcs. From these evaluations, it is found that as the number of segments is increased, the matching coefficient increases from 0.14 to 0.50, the Euclidean distance decreases from 32 nm to 26 nm,and the curvature becomes close to the standard value.
基金Projects(52205069,52075083,52304049)supported by the National Natural Science Foundation of ChinaProject(2021-BS-164)supported by the Liaoning Province Doctoral Research Startup Fund,China+2 种基金Project(LJKZ0264)supported by the Science and Technology Research Projects of Education Department of Liaoning Province,ChinaProject(G2022003010L)supported by the High-end Foreign Experts Recruitment Plan of ChinaProject(E2021203095)supported by the Natural Science Foundation for Young Scholars of Hebei Province,China。
文摘The worm wheel whose undercutting characteristic is researched is a member of offsetting normal arc-toothed cylindrical worm drive.The tooth profile of the worm in its offsetting normal section is a circular arc.The normal vector used to calculate the first-type limit function is determined in the natural frame without the aid of the curvature parameter of worm helicoid.The first-type limit line is ascertained via solving the nonlinear equations iteratively.It is discovered that one first-type limit line exists on the tooth surface of worm wheel by numerical simulation,and such a line is normally located out of the meshing zone.Only one intersection point exists between the first and second-types of limit lines,and this point is a lubrication weak point.The undercutting mechanism is essentially that a part of the meshing zone near the conjugated line of worm tooth crest will come into the undercutting area and will be cut off during machining the worm wheel.The machining simulation verifies the correctness of undercutting mechanism.Moreover,a convenient and practical characteristic quantity is proposed to judge whether the undercutting exists in the whole meshing zone via computing the first-type limit function values on the worm tooth crest.
基金support from the National Natural Science Foundation of China(Nos.12102242 and 12172086)the Educational Foundation of Liaoning Province(No.JYTQN2023261)the Key R&D Program of Shandong Province of China(No.2022SFGC0801).
文摘The propagation of solitary waves in fiber-reinforced hyperelastic cylindrical shells holds tremendous potential for structural health monitoring.However,solitary waves under external forces are unstable,and may break then cause chaos in severe cases.In this paper,the stability of solitary waves and chaos suppression in fiber-reinforced compressible hyperelastic cylindrical shells are investigated,and sufficient conditions for chaos generation as well as chaos suppression in cylindrical shells are provided.Under the radial periodic load and structural damping,the traveling wave equation describing the single radial symmetric motion of the cylindrical shell is obtained by using the variational principle and traveling wave method.By employing the bifurcation theory of dynamical systems,the parameter space for the appearance of peak solitary waves,valley solitary waves,and periodic waves in an undisturbed system is determined.The sufficient conditions for chaos generation are derived by the Melnikov method.It is found that the disturbed system leads to chaotic motions in the form of period-doubling bifurcation.Furthermore,a second weak periodic disturbance is applied as the non-feedback control input to suppress chaos,and the initial phase difference serves as the control parameter.According to the Melnikov function,the sufficient conditions for the second excitation amplitude and initial phase difference to suppress chaos are determined.The chaotic motions can be successfully converted to some regular motions by weak periodic perturbations.The results of theoretical analyses are compared with numerical simulation,and they are in good agreement.This paper extends the research scope of nonlinear elastic dynamics,and provides a strategy for controlling chaotic responses of hyperelastic structures.
文摘The effects of a harmonically exciting monopole source on an infinitely long cylindrical cavity embedded entirely within a fluid-saturated poroelastic formation of infinite extent are examined theoretically.It is assumed that the source is located outside the cavity at a specified distance from the borehole axis.The magnitudes of the hoop and radial stresses beside the pore pressures exerted on the interface and inside the porous medium surrounding the borehole are calculated and discussed.Biot's poroelastic modeling along with three types of boundary conditions for the cylindrical interface including the ideal fluid,empty borehole,and rigid inclusion with a hard boundary is employed for the analysis.Utilizing a proper translational addition theorem for expressing the incident spherical wave in terms of cylindrical wave expansions,the proposed boundary conditions at the interface are satisfied.Stresses are formulated by means of wave potential functions in a three-dimensional(3D)manner.The effects of the frequency and the radial distance between the source and borehole on the induced stresses are examined for the first cylindrical modes over frequency spectra.Two permeability conditions for the interface and three types of soils for the porous formation are considered throughout the analysis.To give an overall outline of the study,a numerical example is presented.The results clearly indicate that the distance is a key parameter and has considerable effects on the induced stress values.In addition,the interface permeability condition and soil characteristics play an important role in determining the dynamic response of the borehole.Finally,the obtained results are compared with the relevant analyses existing in the literature for some limit cases,and good agreement is achieved.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52271317 and 52071149)the Fundamental Research Funds for the Central Universities(HUST:2019kfy XJJS007)。
文摘To address the problems of low accuracy by the CONWEP model and poor efficiency by the Coupled Eulerian-Lagrangian(CEL)method in predicting close-range air blast loads of cylindrical charges,a neural network-based simulation(NNS)method with higher accuracy and better efficiency was proposed.The NNS method consisted of three main steps.First,the parameters of blast loads,including the peak pressures and impulses of cylindrical charges with different aspect ratios(L/D)at different stand-off distances and incident angles were obtained by two-dimensional numerical simulations.Subsequently,incident shape factors of cylindrical charges with arbitrary aspect ratios were predicted by a neural network.Finally,reflected shape factors were derived and implemented into the subroutine of the ABAQUS code to modify the CONWEP model,including modifications of impulse and overpressure.The reliability of the proposed NNS method was verified by related experimental results.Remarkable accuracy improvement was acquired by the proposed NNS method compared with the unmodified CONWEP model.Moreover,huge efficiency superiority was obtained by the proposed NNS method compared with the CEL method.The proposed NNS method showed good accuracy when the scaled distance was greater than 0.2 m/kg^(1/3).It should be noted that there is no need to generate a new dataset again since the blast loads satisfy the similarity law,and the proposed NNS method can be directly used to simulate the blast loads generated by different cylindrical charges.The proposed NNS method with high efficiency and accuracy can be used as an effective method to analyze the dynamic response of structures under blast loads,and it has significant application prospects in designing protective structures.
基金Project supported by the National Natural Science Foundation of China(Nos.12202039,52204085,and 52474123)。
文摘This paper theoretically investigates the influence of a cylindrical PN junction on the propagation characteristics of shear cylindrical waves(SCWs)in an infinitely long piezoelectric semiconductor(PS)concentric cylinder structure.This PS concentric cylinder structure is composed of three regions:an inner PS cylinder,an outer PS cylindrical shell,and a cylindrical PN junction at the interface between the two aforementioned regions.First,the basic equations of the PS concentric cylinder structure are derived,taking into account the coupling of the mechanical displacement,electric potential,and charge carrier perturbation in the cylindrical coordinate system.Next,a mathematical model for the SCWs in this PS concentric cylinder structure is established,utilizing the spectral method and considering the physical characteristics of the cylindrical PN junction.Finally,the dispersion and attenuation curves of the SCWs are numerically calculated to discuss the influence of the interface effect resulting from the cylindrical PN junction.It is found that the existence of a cylindrical PN junction can either reduce or enhance the mechanical-to-electrical energy conversion,which is closely related to the doping mode,doping concentration,and curvature radius of the cylindrical interface.A reasonable design of the aforementioned parameters can optimize the wave motion in acoustic equipment formed by PS media with different frequencies or wavelengths.The construction and resolution of the mathematical model as well as the analysis of physical mechanisms can offer theoretical guidance for improving the efficiency of energy conversion from mechanical energy to electrical energy and optimizing the acoustic performance of energy harvesting devices.
基金The Natural Science Foundation of Liaoning Province of China(Grant No.2023-MSLH-314)he 2024 Yingkou Institute of Technology Campus level Scientific Research Project(FDL202408)+1 种基金The Foundation of Liaoning Provincial Key Laboratoryof Energy Storageand Utilization(GrantNo.CNNK202406)Yingkou Instituteof Technology campus level research project-Development of food additive supercriticalextraction equipment and fluid transmission systemresearch(Grant No.HX202427).
文摘Thermal conductivity is an important physical parameter in thermal equipment,in the blast furnace,rotary kiln and other equipment,multi-layer cylindrical wall is extremely important in industrial production of a thermal conductivity model,its thermal conductivity coefficient determines the ability of the cylindrical wall,which results in the existence of a large number of multi-layer cylinder thermal conductivity problems of the pitfalls.This paper focuses on the establishment of a mathematical model of the multi-layer cylinder thermal conductivity problem,by applying different voltages to the multi-layer cylinder wall,study the temperature distribution of the multi-layer cylinder wall under the conditions of natural convection and forced convection,and draw the line graphs under the conditions of natural convection and forced convection by Origin software,and finally conclude that:under the same conditions,the forced convection is significantly stronger than the natural convection;under the conditions of different voltages,the multi-layer cylinder wall under the conditions of steady state convection,the forced convection is much stronger than natural convection.Under different voltage conditions,the temperature of the multilayer cylinder wall under steady state conditions increases with the increase of voltage,which provides a strong support for the related research.
文摘Most of the existing studies on tunnel blast wave are based on spherical or grouped charges, however,conventional weapons are mostly cylindrical rather than spherical. In order to analyze the impact of cylindrical charges on the tunnel blast wave loads and to develop a quantitative calculation method, this study carried out experimental and numerical research. Initially, external explosion experiments were conducted using both 35 kg spherical charges and cylindrical charges with aspect ratio of 4.8 at two different distances from the tunnel entrance. Comparative analysis of the blast wave parameters in the tunnel revealed that the explosive equivalent of the cylindrical charges was significantly higher than that of the spherical charges. To address this, an equivalent coefficient κ based on the spherical charges was proposed for the cylindrical charges. Subsequently, numerical simulations were conducted for the experimental conditions, and the numerical simulation results match the experiments well. Through numerical calculations, the reliability of the equivalent coefficient κ under the experimental conditions was verified, and comparison analysis indicated that the explosion energy of cylindrical charges spreads more radially, resulting in more explosion energy entering the tunnel, which is the fundamental reason for the increase in tunnel blast wave loads. Additionally, analyzing the explosion energy ratio entering the tunnel is an effective method for calculating the equivalent coefficient κ. Finally, through more than one hundred sets of numerical calculation results, the impact of the proportional distance λ and the ratio of charge mass to the tunnel cross-section dimension φ on the equivalence coefficients κ was investigated. An empirical formula for the equivalence coefficient κ was derived through fitting, and the accuracy of the formula was validated through literature experimental results. The research findings of this paper will provide valuable guidance for the calculation of blast wave loads in tunnel.
基金funded by the Sichuan Science and Technology Program(Project Nos.2024NSFSC0140,2023NSFSC0414,2022NSFSC0454)Panzhihua City Provincial Targeted Financial Resources Transfer Payment(Grant No.222Y2F-GG-04)+4 种基金Open Project of the Key Laboratory of Process Equipment and Control in Sichuan Province(ProjectNo.GK202211)Cultivation Research Project of PanzhihuaUniversity(ProjectNo.2023PY11)Open Project of Sichuan Provincial Engineering Technology Research Center for Advanced Manufacturing of Titanium Alloys(Project No.TM-2023-Z-02)Open Project of Panzhihua Key Laboratory of Advanced Manufacturing Technology(Project No.2022XJZD05).
文摘The fixed-setting face-milled curvilinear cylindrical gear features teeth that are arc-shaped along the longitudinal direction.Some researchers hypothesize that this arc-tooth may enhance the lubrication conditions of the gear.This study focuses on this type of gear,employing both finite element analysis(FEA)and analytical methods to determine the input parameters required for elastohydrodynamic lubrication(EHL)analysis.The effects of assembly errors,tooth surface modifications,load,and face-milling cutter radius on the lubrication performance of these gears are systematically investigated.The finite element model(FEM)of the gear pair is utilized to calculate the coordinates of contact points on the tooth surface and the corresponding contact pressures at the tooth surface nodes throughout a meshing cycle.Subsequently,the normal load on specific gear teeth is determined using a gradient-based approach.Entrainment speed,slip-to-roll ratio,and effective radius near the contact points on the tooth surface are derived through analytical methods.The data obtained from FEA serve as input parameters for EHL simulations.The lubrication performance of the curvilinear cylindrical gear is evaluated through example studies.The findings indicate that using FEA to provide input parameters for EHL simulations can reveal the occurrence of edge contact phenomena during gear meshing,allowing for a more accurate representation of the gear’s lubrication conditions.The lubrication performance of the curvilinear cylindrical gear is shown to be independent of the face-milling cutter radius but is significantly influenced by the size of the contact pattern on the tooth surface.Curvilinear gears with larger contact patterns demonstrate superior lubrication performance.
基金supported by the National Natural Science Foundation of China(Grant No.12302437)Natural Science Foundation of Jiangsu Province(Grant No.SBK2023045424)。
文摘Waveform regulator in charge is a method that can realize multi-source detonation wave superposition through a single point detonation.The method does not need to weaken the strength of shell,and relies on the high stress generated by superposition to cut shell into regular fragments.Additionally,it can be combined with different initiation methods to alter the fragmentation outcomes.In this study,aiming at the fracture strain of metal cylindrical shell driven by explosive charge with waveform regulator,theoretical analysis was first adopted to obtain the prediction model of the fracture strain of cylindrical shell with waveform regulator and the model of the axial distribution of the stress concentration factor.On this basis,both theoretical analysis and numerical models were utilized to investigate the effect of waveform regulator on the initial velocity of fragments.Finally,experiments were conducted to validate the fracture strain prediction model for cylindrical shell with waveform regulator.The research results show that the collision angles of the detonation waves at different axial positions are different,which leads to the stress concentration factor on the shell presenting a trend of gradually decreasing,then sharply increasing,and then rapidly decreasing along the axial direction.Additionally,the changes in the slot spacing and the thickness of outer charge will also affect the stress concentration factor,and the influence of outer charge thickness is relatively large.The smaller the ratio of charge volume to waveform regulator volume,the larger the axial sparse wave intensity and the more the fragment initial velocity decrease.From the initiation end to the non-initiation end,the failure modes of the shell sequentially change from pure shear,to mixed tensile-shear,and finally to pure tensile failure.The experimental results are in good agreement with the calculated results of the fracture strain model,and the maximum relative error is less than 10%,which indicates that the fracture strain prediction model of the cylindrical shell with waveform regulator established in this paper by considering the increase of elastic energy per unit volume caused by stress concentration on the shell is reliable.
基金Project supported by the Science and Technology Plan Joint Program of Liaoning Province of China(Natural Science Foundation-Doctoral Research Launch Project)(No.2024-BSLH-027)the Fundamental Research Funds for Undergraduate Universities of Liaoning Province of China(No.LJBKY2024033)+1 种基金the National Natural Science Foundation of China(No.12472064)the Natural Science Foundation of Liaoning Province of China(No.2023-MS-118)。
文摘In recent years,magneto-electro-elastic(MEE)cylindrical shells with step-wise thicknesses have shown significant potential in the field of vibration energy harvesting.To aid the design of such energy harvesting devices,an accurate free vibration analysis of embedded MEE cylindrical shells with step-wise thicknesses is performed within the framework of symplectic mechanics.By using the Legendre transformation,a new known vector is defined to transform the higher-order partial differential governing equations into a set of lower-order ordinary differential equations.Therefore,the original vibration analysis is regarded as an eigen problem in the symplectic space,and analytical solutions can be represented by the symplectic series.In numerical examples,the new analytical solutions are compared with the existing results,and good agreement is observed.Furthermore,the effects of critical design parameters on free vibration characteristics are thoroughly investigated.All numerical results can serve as benchmarks for the development of other approximate or numerical methods.
基金supported by the National Natural Science Foundation of China(No.12172321)。
文摘The nonlinear traveling wave vibration of rotating ferromagnetic functionally graded(FG)cylindrical shells under multi-physics fields is investigated.Grounded in the Kirchhoff-Love thin shell theory,the geometric nonlinearity is incorporated into the model,and the constitutive equations are derived.The physical parameters of functionally graded materials(FGMs),which exhibit continuous variation across the thickness gradient,are of particular interest.The nonlinear magneto-thermoelastic governing equations are derived in accord with Hamilton's principle.The nonlinear partial differential equations are discretized with the Galerkin method,and the analytical expression of traveling wave frequencies is derived with an approximate method.The accuracy of the proposed method is validated through the comparison with the results from the literature and numerical solutions.Finally,the visualization analyses are conducted to examine the effects of key parameters on the traveling wave frequencies.The results show that the factors including the power-law index,temperature,magnetic field intensity,and rotating speed have the coupling effects with respect to the nonlinear vibration behavior.
基金supported by the National Natural Science Foundation of China(Grant Nos.12020101001,12021002,12372324,and 12272239)supported by the National Innovation and Entrepreneurship Training Program for College Students(No.202210056136).
文摘The multi-layer cylindrical helicoidal fiber structure(MCHFS)exists widely in biological materials such as bone and wood at the microscale.MCHFSs typically function as reinforcing elements to enhance the toughness of materials.In this study,we establish a shear lag-based pullout model of the cylindrical helicoidal fiber(CHF)for investigating interlayer stress transfer and debonding behaviors,with implications regarding the underlying toughening mechanism of MCHFS.Based on the shear lag assumptions,analytical solutions for the stress and displacement fields of the MCHFS during the pullout are derived by considering the CHF as a cylindrically monoclinic material and verified through the 3D finite element simulation.It is found that the helical winding of CHF results in both axial and hoop interlayer shear stresses.Both the helical winding angle and the elastic moduli of the fiber and matrix have significant influences on interlayer stress transfer.This work reveals a new interlayer stress transfer mechanism in the MCHFS existing widely in biological materials.
基金Supports from the National Natural Science Foundation of China(Grant No.12272094,No.52205185 and No.51975123)the Natural Science Foundation of Fujian Province of China(Grant No.2022J01541 and No.2020J05102)the Key Project of National Defence Innovation Zone of Science and Technology Commission of CMC(Grant No.XXX-033-01)。
文摘To explore the wide-frequency damping and vibration-attenuation performances in the application of aerospace components,the cylindrical sandwich shell structure with a gradient core of entangled wire mesh was proposed in this paper.Firstly,the gradient cores of entangled wire mesh in the axial and radial directions were prepared by using an in-house Numerical Control weaving machine,and the metallurgical connection between skin sheets and the gradient core was performed using vacuum brazing.Secondly,to investigate the mechanical properties of cylindrical sandwich shells with axial or radial gradient cores,quasi-static and dynamic mechanical experiments were carried out.The primary evaluations of mechanical properties include secant stiffness,natural frequency,Specific Energy Absorption(SEA),vibration acceleration level,and so on.The results suggest that the vibration-attenuation performance of the sandwich shell is remarkable when the high-density core layer is at the end of the shell or abuts the inner skin.The axial gradient material has almost no influence on the vibration frequencies of the shell,whereas the vibration frequencies increase dramatically when the high-density core layer approaches the skin.Moreover,compared to the conventional sandwich shells,the proposed functional grading cylindrical sandwich shell exhibits more potential in mass reduction,stiffness designing,and energy dissipation.
基金the National Natural Science Foundation of China (No.U22B2086)the National Science and Technology Major Project through (No.2019-VII-0017-0158).
文摘Shot peening is commonly employed for surface deformation strengthening of cylindrical surface part.Therefore,it is critical to understand the effects of shot peening on residual stress and surface topography.Compared to flat surface,cylindrical surface shot peening has two significant features:(i)the curvature of the cylindrical surface and the scattering of the shot stream cause dis-tributed impact velocities;(i)the rotation of the part results in a periodic variation of the impact velocity component.Therefore,it is a challenge to quickly and accurately predict the shot peening residual stress and surface topography of cylindrical surface.This paper developed a high-precision model which considers the more realistic shot peening process.Firstly,a kinematic analysis model was developed to simulate the relative movement of numerous shots and cylindrical surface.Then,the spatial distribution and time-varying impact information was calculated.Subsequently,the impact information was used for finite element modeling to predict residual stress and surface topography.The proposed kinematic analysis method was validated by comparison with the dis-crete element method.Meanwhile,9310 high strength steel rollers shot peening test verified the effectiveness of the model in predicting the residual stress and surface topography.In addition,the effects of air pressure and attack angle on the residual stress and surface topography were investigated.This work could provide a functional package for efficient prediction of the surface integrity and guide industrial application in cylindrical surface shot peening.
基金supported by the National Natural Science Foundation of China(Grant Nos.12225206 and 11921002)the Tsinghua National Laboratory for Information Science and Technology,and a grant from the Institute for Guo Qiang,Tsinghua University(Grant No.2021GQG1009).
文摘Mechanical-guided assembly of three-dimensional(3D)mesostructures from pre-defined 2D precursors based on the deterministically controlled buckling has attracted increasing attention in both fundamental and applied research areas,owing to the compelling advantages in developing flexible electronic devices with complex 3D geometries and novel functions.Recently,a buckling-guided strategy was reported to enable assembly of complex 3D mesostructures and electronic devices on cylindrical and cylinder-like substrates,which can be integrated with vascular systems for monitoring of flow rate and other physical signals.A clear understanding of nonlinear buckling deformations of elastic beams assembled on cylindrical substrates is thereby essential for the relevant structural design.In this work,we present a systematic study on the nonlinear deformations of buckled ribbon-type structures on cylindrical substrates.Two representative classes of ribbon-type structures are considered,including arc structures and serpentine structures.Starting with the finite-deformation beam theory,a theoretical model is established to investigate deformed configurations resulted from the controlled buckling,including ribbons assembled on both outer and inner surfaces of the substrate.The structure-substrate contact and self-contact are taken into account in the analyses,which could lead to distinct deformed configurations.Both experimental studies and finite element analyses(FEA)were carried out to validate the developed theoretical model.A demonstrative device design based on the 3D ribbon network outside the cylindrical substrate suggests potential applications in energy harvesting across a broad range of frequency.The theoretical model presented herein could offer insights for the practical design of 3D electronic devices that can be conformally integrated with curvy biological surfaces.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51978336 and 11702117)the Science and Technology Plan Project of Department of Communications of Zhejiang Province(Grant No.2021051)Nantong City Social Livelihood Science and Technology Project(Grant No.MS22022067).
文摘The sloshing in a group of rigid cylindrical tanks with baffles and on soil foundation under horizontal excitation is studied analytically.The solutions for the velocity potential are derived out by the liquid subdomain method.Equivalent models with mass-spring oscillators are established to replace continuous fluid.Combined with the least square technique,Chebyshev polynomials are employed to fit horizontal,rocking and horizontal-rocking coupling impedances of soil,respectively.A lumped parameter model for impedance is presented to describe the effects of soil on tank structures.A mechanical model for the soil-foundation-tank-liquid-baffle system with small amount of calculation and high accuracy is proposed using the substructure technique.The analytical solutions are in comparison with data from reported literature and numerical codes to validate the effectiveness and correctness of the model.Detailed dynamic properties and seismic responses of the soil-tank system are given for the baffle number,size and location as well as soil parameter.
