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Bandgap characteristics of the two-dimensional missing rib lattice structure

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Applied Mathematics and Mechanics(English Edition) 2022年第11期43卷 1631-1640页

作者： Fan YANG Zhaoyang MA xingming guo Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringShanghai UniversityShanghai 200072China

In this paper,the bandgap characteristics of a missing rib lattice structure composed of beam elements are investigated by using the Floquet-Bloch *** tuning of the width and position of the bandgap is achieved by changing the local structural parameters,i.e.,the rotation angle,the short beam length,and the beam *** order to expand the regulation of the bandgap,the influence of the material parameters of the crossed long beams inside the structure on the bandgap is *** results show that the mass density and stiffness of the structure have significant effects on the bandgap,while Poisson’s ratio has no effect on the *** analyzing the first ten bands of the reference unit cell,it can be found that the missing rib lattice structure generates multiple local resonance bandgaps for vibration reduction,and these bandgap widths are *** modal analysis reveals that the formation of the bandgap is due to the dipole resonance of the lattice structure,and this dipole resonance originates from the coupling of the bending deformation of the beam *** the band structure,the vibrational mode of the 9th band with a negative slope corresponds to a rotational resonance,which is different from that with the conventional negative slope formed by the coupling of two resonance *** study can provide a theoretical reference for the design of simple and lightweight elastic metamaterials,as well as for the regulation of bandgaps and the suppression of elastic waves.

关键词： elastic metamaterial missing rib structure Floquet-Bloch theorem bandgap vibration mode

Dynamic analysis of wind turbine tower structures in complex ocean environment

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Applied Mathematics and Mechanics(English Edition) 2020年第7期41卷 999-1010页

作者： Guanzhong LIU xingming guo Li ZHU Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200072China School of Mathematics and Computational Sciences Xiangtan UniversityXiangtan 411105Hunan ProvinceChina

Studying and analyzing the dynamic behavior of offshore wind turbines are of great importance to ensure the safety and improve the efficiency of such expensive *** this work,a tapered beam model is proposed to investigate the dynamic response of an offshore wind turbine tower on the monopile foundation assembled with rotating blades in the complex ocean *** environment factors like wind,wave,current,and soil resistance are taken into *** proposed model is ana-lytically solved with the Galerkin *** on the numerical results,the effects of various structure parameters including the taper angle,the height and thickness of the tower,the depth,and the diameter and the cement filler of the monopile on the funda-mental natural frequency of the wind turbine tower system are investigated in *** is found that the fundamental natural frequency decreases with the increase in the taper angle and the height and thickness of the tower,and increases with the increase in the diameter of the ***,filling cement into the monopile can effectively im-prove the fundamental natural frequency of the wind turbine tower system,but there is a critical value of the amount of cement maximizing the property of the *** research may be helpful in the design and safety evaluation of offshore wind turbines.

关键词： wind turbine tower structure dynamic analysis tapered beam fundamen-tal natural frequency complex ocean environment

Controlled wrinkling analysis of thin films on gradient substrates

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Applied Mathematics and Mechanics(English Edition) 2017年第5期38卷 617-624页

作者： Jianzhong ZHAO xingming guo Lu LU Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringShanghai UniversityShanghai 200072China

The paper investigates continuously changing wrinkle patterns of thin films bonded to a gradient substrate. Three types of gradient substrates including exponential, power-law, and symmetry models are considered. The Galerkin method is used to dis- cretize the governing equation of film bonded to gradient substrates. The wavelength and the normalized amplitude of the wrinkles for substrates of various material gradients are obtained. The numerical simulation based on the finite element method （FEM） is used to evolve the wrinkle patterns. The result agrees well with that of the analytical model. It is concluded that localization of wrinkle patterns strongly depends on the material gradient. The critical membrane force depends on both the minimum value of wrinkle stiffness and the gradient of wrinkle stiffness when the wrinkle stiffness is at its minimum. This work provides a better understanding for local wrinkle formation caused by gradient substrates.

关键词： thin film gradient substrate wrinkle material gradient Galerkin method

A new tunable elastic metamaterial structure for manipulating band gaps/wave propagation

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Applied Mathematics and Mechanics(English Edition) 2021年第11期42卷 1543-1554页

作者： Zhenyu WANG Zhaoyang MA xingming guo Dongsheng ZHANG Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringShanghai UniversityShanghai 200444China

A one-dimensional mechanical lattice system with local resonators is proposed as an elastic metamaterial model,which shows negative mass and negative modulus under specific frequency *** proposed representative units,consisting of accurately arranged rigid components,can generate controllable translational resonance and achieve negative mass and negative modulus by adjusting the local structural parameters.A shape memory polymer is adopted as a spring component,whose Young’s modulus is obviously affected by temperature,and the proposed metamaterials’tunable ability is achieved by adjusting *** effect of the shape memory polymer’s stiffness variation on the band gaps is investigated detailedly,and the special phenomenon of intersecting dispersion curves is discussed,which can be designed and controlled by adjusting *** dispersion relationship of the continuum metamaterial model affected by temperature is obtained,which shows great tunable ability to manipulate wave propagation.

关键词： tunable elastic metamaterial negative mass negative modulus

Quality evaluation of rubber-to-metal bonded structures based on shearography

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Science China(Physics,Mechanics & Astronomy) 2015年第7期58卷 49-56页

作者： LIU Bin guo xingming QI GongJin ZHANG DongSheng Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy Engineering Beijing Aeronautical Technology Research Center Department of Mechanics Shanghai University

The quality of bonding is often a concern in rubber-to-metal bonded parts with regard to the integrity and stability of the structure. In this study, shearography has been used to detect the out-of-plane deformation of the defects caused by thermal and vacuum stresses. A sample of the vulcanized styrene-butadiene rubber bonded to steel with known artificial voids was prepared and during bonding process a region was glued with thick adhesives. The rubber surface of the sample was inspected in thermal radiation and vacuum modes respectively with a self-designed shearography device. Meanwhile, a numerical simulation was conducted to predict the out-of-plane deformation of the rubber surface in these two stress modes. Results from the numerical simulation and the experiments indicated that the debonding defects could be inspected in both loading modes. In the thermal radiation mode the region with thick adhesives could be identified successfully. This study provides a guideline for quality control of rubber-to-metal structures using an optical method.

关键词： shearography optical mechanics debonding

A nonlocal strain gradient shell model incorporating surface effects for vibration analysis of functionally graded cylindrical nanoshells

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Applied Mathematics and Mechanics(English Edition) 2019年第12期40卷 1695-1722页

作者： Lu LU Li ZHU xingming guo Jianzhong ZHAO Guanzhong LIU Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy Engineering School of Mechanics and Engineering ScienceShanghai UniversityShanghai 200072 China Department of Mechanical Engineering University of Alberta School of Mathematics and Computational Sciences Xiangtan UniversityXiangtan 411105 Hunan Province China

In this pap er, a novel size-dep endent functionally graded (FG) cylindrical shell model is develop ed based on the nonlocal strain gradient theory in conjunction with the Gurtin-Murdoch surface elasticity theory . The new model containing a nonlocal parameter, a material length scale parameter, and several surface elastic constants can capture three typical typ es of size e ects simultaneously , which are the nonlocal stress ef- fect, the strain gradient e ect, and the surface energy e ects. With the help of Hamilton’s principle and rst-order shear deformation theory , the non-classical governing equations and related b oundary conditions are derived. By using the prop osed model, the free vibra- tion problem of FG cylindrical nanoshells with material prop erties varying continuously through the thickness according to a p ower-law distribution is analytically solved, and the closed-form solutions for natural frequencies under various b oundary conditions are obtained. After verifying the reliability of the prop osed model and analytical method by comparing the degenerated results with those available in the literature, the in uences of nonlocal parameter, material length scale parameter, p ower-law index, radius-to-thickness ratio, length-to-radius ratio, and surface e ects on the vibration characteristic of func- tionally graded cylindrical nanoshells are examined in detail.

关键词： nonlocal strain gradient theory surface elasticity theory rst-order shear deformation theory vibration functionally graded (FG) cylindrical nanoshell

Tailoring fluorine-rich solid electrolyte interphase to boost high efficiency and long cycling stability of lithium metal batteries

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Science China Chemistry 2023年第7期66卷 2121-2129页

作者： Tianyang Xue Ji Qian xingming guo Yi Chen Kaixin Yu Tianyang Yu Yao Li Li Li Feng Wu Renjie Chen Beijing Key Laboratory of Environmental Science and Engineering School of Materials Science and EngineeringBeijing Institute of TechnologyBeijing 100081China Institute of Advanced Technology Beijing Institute of TechnologyJinan 250300China Collaborative Innovation Center of Electric Vehicles in Beijing Beijing 100081China

Lithium metal batteries(LMBs)are regarded as the most promising next-generation battery system due to their high energy ***,Li dendrite growth and low Coulombic efficiency(CE)of Li metal anodes limit their *** solid electrolyte interphase(SEI)is an extremely effective method to solve these problems and using electrolyte additives to regulate the SEI is one of the most effective ***,we study the feasibility of trans-difluoroethylene carbonate(DFEC)used as the solvent additive in conventional ether electrolyte,which has excellent anti-reduction stability against Li *** result shows that a Li/Cu half-cell with the modified electrolyte can be steadily cycled for 300 cycles with an average CE of 97.41%at the current density of 0.5 m A cm^(-2)and with 97.1%for 140 cycles at 1 m A cm^(-2).Besides,the Li/LFP full cell with the modified electrolyte displays an improved capacity retention of 94.55%after 520 cycles with an average CE of 99.74%at 1 *** contrast,the capacity retention of 56.2%and CE of 99.15%is obtained for the cell with pure ether *** SEM images show that the DFEC enables dense Li deposition,and the FTIR and XPS spectra confirm the formation of Li Frich SEI with the *** work demonstrates the feasibility of using DFEC as the solvent additive in ether electrolyte to construct Li F-rich SEI,and it will provide important insight in developing high-performance electrolytes for LMBs.

关键词： lithium metal batteries ether electrolyte trans-difluoroethylene carbonate LiF-rich SEI dense Li deposition

Buckling of a stiff thin film on a functionally gradient material substrate

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Buckling of a stiff thin film on a functionally gradient mat...

On Solutions of a Differential Inclusion

第十五届现代数学和力学学术会议

作者： Jianzhong Zhao xingming guo Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai University

The present work is inspired by the fact that the stiff film bonded to a functionally graded material(FGM)substrate forms a pattern of continuous changing of the wrinkle wavelength after *** contrast to the commonly u...

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Advances in Manufacturing 1998年第1期2卷 27-29页

作者： guo xingming (Shanghai Institute of Applied Mathematics and Mechanics) Shanghai Institute of Applied Math. & Mech. Shanghai University Shanghai

In this paper the solutions of a second order non autonomous differential inclusion is discussed by means of some properties of set valued *** existence of solutions is established,and minimum and balance principle... 详细信息

关键词： convex non autonomous subdiffertial set valued mapping.