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Mechanics of twisted and coiled tube-based artificial muscles driven by hydraulic pressure

Science China(Technological Sciences) 2025年第4期68卷 72-81页

作者： Hao LIU Zhiya ZHANG Lei LIU Dabiao LIU Department of Engineering Mechanics School of Aerospace EngineeringHuazhong University of Science and TechnologyWuhan430074China Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment Wuhan430074China

The twisted and coiled polymer(TCP)artificial muscles driven by hydraulic pressure offer high mechanical efficiency and power *** relation between geometry,mechanics,and actuation performance for this kind of muscle is *** this study,we study the mechanics and actuation characteristics of TCP tube-based muscles driven by hydraulic pressure through experiment,theory,and finite element *** for the helical geometry and transverse isotropy of the TCP muscles,we develop a phenomenological model to predict the actuation performance of TCP tube-based *** torsional and tensile actuation characteristics of the twisted and TCP tube-based muscle driven by hydraulic pressure are *** is found that the cold drawing enhances the anisotropy of the polyvinyl chloride tube,resulting in an improved actuation performance of the twisted and TCP *** torsional actuation in the twisted tube reaches the maximum at a critical bias angle for a given pressure,while the tensile actuation in TCP muscles increases with the coil *** theoretical predictions and simulations are in good agreement with experimental *** study is significant for guiding the design of TCP tube-based muscles and achieving their precise actuation control.

关键词： artificial muscles hydraulic pressure actuation characteristics anisotropy

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Effects of Strain and Strain Rates on Microstructure Evolution Within ASB of TC4

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Acta Mechanica Solida Sinica 2024年第6期37卷 958-966页

作者： Qiang Zhou Qilin Xiong Zhaoquan Zeng Department of Mechanics School of Aerospace EngineeringHuazhong University of Science and Technology1037 Luoyu RoadWuhan430074China Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment 1037 Luoyu RoadWuhan430074China

Adiabatic shear band(ASB),a typical failure mechanism in a metal at high strain rates,is hardly controllable or predictable to some *** development of the microstructure plays a crucial role in its *** this paper,the effect of strain rate on the development of microstructure in ASB of titanium alloy TC4 is investigated using hat-shaped specimens with the split-Hopkinson pressure bar *** results show that the fracture strength of TC4 is significantly dependent on the shear strain *** increase in fracture strength from a strain rate of 11,300 s^(−1)to 24,930 s^(−1)is much higher than that from 24,930 s^(−1)to 35,620 s^(−1),which can be attributed to the effect of strain rate on dislocation *** in both as-received and deformed states are investigated using various characterization techniques such as electron backscatter diffraction and X-ray *** region of ASB clearly shows three different microstructural features:random distribution of coarse grains(as received),distribution of elongated grains(transition zone),and distribution of equiaxed nanocrystals(shear-localized zone).The width of ASB increases with the strain *** possible reason for this is that the higher the strain rate,the larger the region where dynamic recrystallization(DRX)occurs due to the accumulation of a large number of *** the middle of ASB,a significant decrease in low-angle grain boundaries(LAGBs)and a large increase in high-angle grain boundaries are *** texture of specimens,especially the{11–20}and{10–10}planes,changes significantly during shear deformation at high strain *** mechanism of continuous dynamic recrystallization can well explain the formation and evolution of DRX within the ASB.

关键词： High strain rates Dynamic recrystallization Adiabatic shear band Microstructure evolution TC4

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The mechanism to reform dynamic performance of an elastic wave-front in a piezoelectric semiconductor by the wave-carrier interaction induced from static biasing fields

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Applied Mathematics and Mechanics(English Edition) 2023年第3期44卷 381-396页

作者： Wanli YANG Jinxi LIU Yizhan YANG Yuantai HU Department of Mechanics Hubei Key Laboratory of Engineering Structural Analysis and Safety AssessmentHuazhong University of Science and TechnologyWuhan 430074China Department of Engineering Mechanics Shijiazhuang Tiedao UniversityShijiazhuang 050043China

The propagation of an elastic wave(EW)in a piezoelectric semiconductor(PSC)subjected to static biasing fields is *** is found that there exist two coupling waves between electric field and charge *** is stimulated by the action of the polarized electric field in the EW-front on charge carriers(EFC),and the other is stimulated by the action of initial electric field in biasing fields on dynamic carriers(IEC).Obviously,the latter is a man-made and tunable wave-carrier interaction.A careful study shows that IEC can play a leading role in remaking dynamic performance of the wave-front and an inter-medium role in transferring energy from biasing fields to ***,a method is proposed to reform the EW performance by biasing-fields:reforming the dispersivity of EW-fronts by promoting competition between IEC and EFC and inverting the dissipation by the IEC to transfer energy from biasing fields to *** corresponding tuning laws on the phase-frequency characteristics of an EW show that the wave velocity can be regulated smaller than the pure EW velocity at a lowfrequency and larger than the pure piezoelectric wave velocity at a *** for regulating the amplitude-frequency characteristics of the EW by the IEC,analyses show that EWs can obtain amplification only for those with relatively high vibration frequencies(small wave lengths).The studies will provide guidance for theoretical analysis of waves propagating in PSCs and practical application and design of piezotronic devices.

关键词： piezoelectric semiconductor(PSC) elastic wave(EW) carrier movement biasing field piezotronic device

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Size effects on the mixed modes and defect modes for a nano-scale phononic crystal slab

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Applied Mathematics and Mechanics(English Edition) 2023年第1期44卷 21-34页

作者： Jun JIN Ningdong HU Hongping HU Department of Mechanics School of Aerospace EngineeringHuazhong University of Science and TechnologyWuhan 430074China Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment Huazhong University of Science and TechnologyWuhan 430074China

The size-dependent band structure of an Si phononic crystal(PnC)slab with an air hole is studied by utilizing the non-classic wave equations of the nonlocal strain gradient theory(NSGT).The three-dimensional(3D)non-classic wave equations for the anisotropic material are derived according to the differential form of the *** on the the general form of partial differential equation modules in COMSOL,a method is proposed to solve the non-classic wave *** bands of the in-plane modes and mixed modes are *** in-plane size effect and thickness effect on the band structure of the PnC slab are *** is found that the thickness effect only acts on the mixed *** relative width of the band gap is widened by the thickness *** effects of the geometric parameters on the thickness effect of the mixed modes are further studied,and a defect is introduced to the PnC supercell to reveal the influence of the size effects with stiffness-softening and stiffness-hardening on the defect *** study paves the way for studying and designing PnC slabs at nano-scale.

关键词： band structure phononic crystal(PnC) nonlocal strain gradient theory(NSGT) size effect

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Nonlinear dynamics of a circular curved cantilevered pipe conveying pulsating fluid based on the geometrically exact model

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Applied Mathematics and Mechanics(English Edition) 2024年第2期45卷 261-276页

作者： Runqing CAO Zilong GUO Wei CHEN Huliang DAI Lin WANG Department of Engineering Mechanics School of Aerospace EngineeringHuazhong University of Science and TechnologyWuhan 430074China Hubei Key Laboratory for Engineering Structural Analysis and Safety Assessment Wuhan 430074China State Key Laboratory of Intelligent Manufacturing Equipment and Technology School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

Due to the novel applications of flexible pipes conveying fluid in the field of soft robotics and biomedicine,the investigations on the mechanical responses of the pipes have attracted considerable *** fluid-structure interaction(FSI)between the pipe with a curved shape and the time-varying internal fluid flow brings a great challenge to the revelation of the dynamical behaviors of flexible pipes,especially when the pipe is highly flexible and usually undergoes large *** this work,the geometrically exact model(GEM)for a curved cantilevered pipe conveying pulsating fluid is developed based on the extended Hamilton's *** stability of the curved pipe with three different subtended angles is examined with the consideration of steady fluid *** attention is concentrated on the large-deformation resonance of circular pipes conveying pulsating fluid,which is often encountered in practical *** constructing bifurcation diagrams,oscillating shapes,phase portraits,time traces,and Poincarémaps,the dynamic responses of the curved pipe under various system parameters are *** mean flow velocity of the pulsating fluid is chosen to be either subcritical or *** numerical results show that the curved pipe conveying pulsating fluid can exhibit rich dynamical behaviors,including periodic and quasi-periodic *** is also found that the preferred instability type of a cantilevered curved pipe conveying steady fluid is mainly in the flutter of the second *** a moderate value of the mass ratio,however,a third-mode flutter may occur,which is quite different from that of a straight pipe system.

关键词： curved pipe conveying fluid pulsating fluid geometrically exact model(GEM) nonlinear dynamics parametric vibration flutter

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Modeling of Cyclic Bending of Thin Foils Using Higher-Order Strain Gradient Plasticity

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Acta Mechanica Solida Sinica 2022年第4期35卷 616-631页

作者： Tong Luo Fenfei Hua Dabiao Liu School of Aerospace Engineering Huazhong University of Science and TechnologyWuhan430074China Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment Wuhan430074China

The plastic behaviors of thin metallic foils,including size effect,Bauschinger effect,and passivation effect,are studied under cyclic bending condition using the strain gradient visco-plasticity *** finite element simulations are performed on the cyclic bending of the elasto-viscoplastic thin foils with passivated and unpassivated *** study is also conducted on the transition from a passivated surface to an unpassivated *** roles of the dissipative and energetic gradient terms are *** the results,it is found that the dissipative gradient terms increase the yield strength,while the energetic gradient terms increase the strain hardening,resulting in an anomalous Bauschinger ***,it is observed that the surface passivation effect increases both the normalized bending moment at initial yielding and strain *** comparison between the numerical results of cases with and without passivation demonstrates that the switching of boundary conditions significantly affects the plastic behavior of the foils under cyclic bending.

关键词： Strain gradient plasticity Size effect Bauschinger effect Geometrically necessary dislocations Bending

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Effect of Hydrogen on Dislocation Nucleation and Motion:Nanoindentation Experiment and Discrete Dislocation Dynamics Simulation

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Acta Mechanica Solida Sinica 2022年第1期35卷 1-14页

作者： Jian Wang Lv Zhao Minsheng Huang Yaxin Zhu Zhenhuan Li Department of Mechanics Huazhong University of Science and TechnologyWuhan 430074China Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment 1037 Luoyu RoadWuhan 430074China

The hydrogen effect on the nucleation and motion of dislocations in single-crystal bcc Fe with(110)surface was investigated by both nanoindentation experiments and discrete dislocation dynamics(DDD)*** results of nanoindentation experiments showed that the pop-in load decreased evidently for the electrochemical hydrogen charging specimen,indicating that the dislocation nucleation strength might be reduced by *** addition,the decrease of hardness due to hydrogen charging was also captured,implying that the dislocation motion might be promoted by *** incorporating the effect of hydrogen on dislocation core energy,a DDD model was specifically proposed to investigate the influence of hydrogen on dislocation nucleation and *** results of DDD simulation revealed that under the effect of hydrogen,the dislocation nucleation strength is decreased and the motion of dislocation is promoted.

关键词： Hydrogen Nanoindentation Homogeneous dislocation nucleation Discrete dislocation dynamics

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The action mechanism of the work done by the electric field force on moving charges to stimulate the emergence of carrier generation/recombination in a PN junction

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Applied Mathematics and Mechanics(English Edition) 2024年第6期45卷 1001-1014页

作者： Lingyun GUO Yizhan YANG Wanli YANG Yuantai HU Department of Mechanics School of Aerospace EngineeringHubei Key Laboratory of Engineering Structural Analysis and Safety AssessmentHuazhong University of Science and TechnologyWuhan 430074China

It is discovered that the product of the current and the electric field in a PN junction should be regarded as the rate of work(power)done by the electric field force on moving charges(hole current and electron current),which was previously misinterpreted as solely a Joule heating *** clarify that it is exactly the work done by the electric field force on the moving charges to stimulate the emergence of non-equilibrium carriers,which triggers the novel physical *** regards to Joule heat,we point out that it should be calculated from Ohm’s law,rather than simply from the product of the current and the electric *** on this understanding,we conduct thorough discussion on the role of the electric field force in the process of carrier recombination and carrier *** thermal effects of carrier recombination and carrier generation followed are incorporated into the thermal equation of *** present study shows that the exothermic effect of carrier recombination leads to a temperature rise at the PN interface,while the endothermic effect of carrier generation causes a temperature reduction at the *** two opposite effects cause opposite heat flow directions in the PN junction under forward and backward bias voltages,highlighting the significance of managing device heating phenomena in design ***,this study possesses referential significance for the design and tuning on the performance of piezotronic devices.

关键词： piezoelectric semiconductor(PS) work done by electric field force thermal effect piezotronic device resistivity conductivity

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analysis OF SWEEP FREQUENCY SIGNAL BASED ON FOURIER TRANSFORM 18

ANALYSIS OF SWEEP FREQUENCY SIGNAL BASED ON FOURIER TRANSFOR...

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18th Symposium on Piezoelectricity, Acoustic Waves, and Device Applications, SPAWDA 2024

作者： Huang, Cansen Liu, Xinhu Hu, Hongping School of Aerospace Engineering Huazhong University of Science and Technology Wuhan China Hubei Key Laboratory for Engineering Structural Analysis and Safety Assessment Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9798331523732

This study aims to explore the application of frequency sweep signal analysis based on discrete Fourier transform in complex environments, in order to improve the accuracy and reliability of signals. Firstly, the significance and application of discrete Fourier transform in signal processing are elucidated. Subsequently, the properties of frequency sweep signals and the challenges they bring in practical scenarios are introduced in detail. Given the complexity of frequency sweep signals, a method based on discrete Fourier transform is proposed. By converting the signal to the frequency domain for spectral analysis, this method can identify the frequency components and energy distribution in the swept frequency signal, thereby promoting accurate analysis and processing of the swept frequency signal. The experimental results show that the use of discrete Fourier transform for frequency sweep signal analysis can effectively extract signal features, reduce noise signal interference, and provide strong support for signal processing and recognition. Therefore, this method has great application prospects in various fields such as communication, radar, and medicine. © 2024 IEEE.

关键词： Discrete Fourier transforms

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Development of a Three-Dimensional Multiscale Octree SBFEM for Viscoelastic Problems of Heterogeneous Materials

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Computer Modeling in engineering & Sciences 2024年第8期140卷 1831-1861页

作者： Xu Xu Xiaoteng Wang Haitian Yang Zhenjun Yang Yiqian He State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentDepartment of Engineering MechanicsDalian University of TechnologyDalian116024China Hubei Key Laboratory of Geotechnical and Structural Safety School of Civil EngineeringWuhan UniversityWuhan430072China Mechanik–Materialtheorie Ruhr-Universität BochumBochum44801Germany

The multiscale method provides an effective approach for the numerical analysis of heterogeneous viscoelastic materials by reducing the degree of freedoms(DOFs).A basic framework of the Multiscale Scaled Boundary Finite Element Method(MsSBFEM)was presented in our previous works,but those works only addressed two-dimensional *** order to solve more realistic problems,a three-dimensional MsSBFEM is further developed in this *** the proposed method,the octree SBFEM is used to deal with the three-dimensional calculation for numerical base functions to bridge small and large scales,the three-dimensional image-based analysis can be conveniently conducted in small-scale and coarse nodes can be flexibly adjusted to improve the computational ***,the Temporally Piecewise Adaptive Algorithm(TPAA)is used to maintain the computational accuracy of multiscale analysis by adaptive calculation in time *** results of numerical examples show that the proposed method can significantly reduce the DOFs for three-dimensional viscoelastic analysis with good *** instance,the DOFs can be reduced by 9021 times compared with Direct Numerical Simulation(DNS)with an average error of 1.87%in the third example,and it is very effective in dealing with three-dimensional complex microstructures directly based on images without any geometric modelling process.

关键词： Three-dimensionalmultiscale viscoelastic analysis numerical base functions octree SBFEM image-based analysis temporally piecewise adaptive algorithm

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