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ANALYTICAL SOLUTIONS FOR A ONE-DIMENSIONAL CHEMO-MECHANICAL COUPLING PROBLEM

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Acta Mechanica Solida Sinica 2014年第2期27卷 137-145页

作者： qingsheng Yang Hui Tian qinghua qin Department of Engineering Mechanics Beijing University of Technology Research School of Engineering Australian National University

Chemo-mechanical coupling exists in a lot of intelligent materials including hy- drogels, biological tissues and other soft materials. These materials are able to respond to ex- ternal stimulus, such as temperature, chemical concentration, and pH value. In this paper, a one-dimensional theoretical model for chemo-mechanical coupling is proposed for analyzing the uniaxial stress/strain state of coupling materials. Based on the chemo-mechanical coupled gov- erning equation, the displacement function and concentration function are derived and the stress and chemical potential are obtained. It is shown that the present chemo-mechanical theory can characterize the chemo-mechanical coupling behavior of intelligent materials.

关键词： intelligent materials chemo-mechanical coupling analytical solution theoretical model constitutive equations hydrogel

A novel oscillator based on heterogeneous carbon@ MoS2 nanotubes

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Nano Research 2016年第6期9卷 1775-1784页

作者： Wugui Jiang Yonghui Zeng qinghua qin Qianghui Luo School of Aeronautical Manufacturing Engineering Nanchang Hangkong University Nanchang 330063 China Research School of Engineering the Australian National University Acton ACT260 I Australia

Oscillatory behavior of novel heterogeneous oscillators composed of carbon and molybdenum disulfide nanotubes （CNT@MST） was investigated for the first time, by using the methods of classical molecular dynamics. In the proposed oscillators, a molybdenum disulfide nanotube （MST） was set as an outer tube, leading to better compatibility with the semiconductor industry standards. A smooth and stable oscillator with a frequency reaching 20 GHz was obtained based on a double-walled CNT@MST hetero-nanotube for a wide range of gap widths, indicating that the proposed oscillators perform much better than those built from double-walled carbon nanotubes （CNTs） that require a narrow range of gap widths. In addition, the oscillation characteristics of CNT@MST oscillators containing different inner and outer tube chirality were significantly better than those of CNT@MST oscillators containing two tubes with the same chirality.

关键词： MoS2 nanotubes carbon nanotubes oscillators hetero-nanotubes molecular dynamics

Mode Ⅲ fracture analysis by Trefftz boundary element method

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Acta Mechanica Sinica 2007年第2期23卷 173-181页

作者： Yuhong Cui Juan Wang Manicka Dhanasekar qinghua qin Department of Mechanics Tianjin UniversityTianjin 300072 China Centre for Railway Engineering Central Queensland UniversityNorth Rockhampton QLD 4702 Australia Department of Engineering Australian National UmversltyCanberra ACT 0200 Australia

This paper presents a hybrid Trefftz （HT） boundary element method （BEM） by using two indirect techniques for mode III fracture problems. Two Trefftz complete functions of Laplace equation for normal elements and a special purpose Trefftz function for crack elements are proposed in deriving the Galerkin and the collocation techniques of HT BEM. Then two auxiliary functions are introduced to improve the accuracy of the displacement field near the crack tips, and stress intensity factor （SIF） is evaluated by local crack elements as well. Furthermore, numerical examples are given, including comparisons of the present results with the analytical solution and the other numerical methods, to demonstrate the efficiency for different boundary conditions and to illustrate the convergence influenced by several parameters. It shows that HT BEM by usingthe Galerkin and the collocation techniques is effective for mode III fracture problems.

关键词： Hybrid Trefftz method. Galerkin technique .Point-collocation technique .Mode III fracture

Ballistic Resistance of Novel Amorphous-Alloy-Reinforced Perforated Armor

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Acta Mechanica Solida Sinica 2021年第1期34卷 12-26页

作者： Tianning Cui qinghua qin Wenmin Yan Tao Wang Jianxun Zhang State Key Laboratory for Strength and Vibration of Mechanical Structures Department of Engineering MechanicsXi’an Jiaotong UniversityXi’an710049China Science and Technology on Transient Impact Laboratory No.208 Research Institute of China Ordnance IndustriesBeijing102202China

A new concept of lightweight structure,namely amorphous-alloy-reinforced perforated armor(ARPA)consisting of the amorphous alloy coating and perforated metal substrate plate,is *** ballistic performance of the ARPA is investigated *** failure modes of ARPA and projectiles are identified,and the defeating mechanism of the ARPA is *** is shown that the amorphous alloy coating is helpful for enhancing the target’s ballistic performance by seriously eroding and fracturing the *** effects of coating thickness,initial impact velocity and impact angle are also discussed for the target’s ballistic *** optimal design of coating thickness may be necessary for enhancing the ballistic resistance of ARPAs.

关键词： Perforated armor plate Amorphous alloy.High-velocity impact.Penetration and perforation Ballistic resistance

Pullout of the Cylindrical Helicoidal Fiber

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Acta Mechanica Solida Sinica 2024年第3期37卷 444-456页

作者： Chenhan Hu Weihao Tao Hongjun Yu qinghua qin Jianshan Wang Department of Mechanics Tianjin UniversityTianjin300054China Department of Astronautic Science and Mechanics Harbin Institute of TechnologyHarbin150001China Department of Materials Science Shenzhen MSU-BIT UniversityShenzhen518172China

The multi-layer cylindrical helicoidal fiber structure(MCHFS)exists widely in biological materials such as bone and wood at the *** typically function as reinforcing elements to enhance the toughness of *** 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 *** 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 *** is found that the helical winding of CHF results in both axial and hoop interlayer shear *** the helical winding angle and the elastic moduli of the fiber and matrix have significant influences on interlayer stress *** work reveals a new interlayer stress transfer mechanism in the MCHFS existing widely in biological materials.

关键词： Cylindrical helicoidal fiber structure Cylindrically monoclinic material Helical winding of fiber Pullout Interlayer stress transfer

Postbuckling Analysis for Offshore Pipelines with Residual Stresses

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China Ocean Engineering 1991年第2期6卷 127-138页

作者： Huang, Yuying qin, qinghua Zhu, Dashan Huazhong Univ of Science and Technology Wuhan China

Based on the finite displacement theory of elastic shells, the postbuckling behaviour of submarine pipelines with residual stresses is investigated by using a new finite element formula. The corresponding complementary energy functional is first constructed, and then a geometrical stiffness matrix suitable for the postbuckling of a cylindrical shell is derived. In this matrix the effects of initial stresses and harmonic coupling terms have been considered. The formulation presented in this paper can be used to solve a significant class of problems in the analysis of elastic shells.

关键词： Mathematical Techniques Finite Element Method

APPLICATION OF TREFFTZ BEM TO ANTI-PLANE PIEZOELECTRIC PROBLEM

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Acta Mechanica Solida Sinica 2006年第4期19卷 352-364页

作者： Wang Juan Cui Yuhong qin qinghua Jia Jiangying Department of Mechanics Tianjin University Tianjin 30072 China Department of Engineering Australian National University Canberra ACT 0200 Australia

Anti-plane electroelastic problems are studied by the Trefftz boundary element method （BEM） in this paper. The Trefftz BEM is based on a weighted residual formulation and indirect boundary approach. In particular the point-collocation and Galerkin techniques, in which the basic unknowns are the retained expansion coefficients in the system of complete equations, are considered. Furthermore, special Trefftz functions and auxiliary functions which satisfy exactly the specified boundary conditions along the slit boundaries are also used to derive a special purpose element with local defects. The path-independent integral is evaluated at the tip of a crack to determine the energy release rate for a mode Ⅲ fracture problem. In final, the accuracy and efficiency of the Trefftz boundary element method are illustrated by an example and the comparison is made with other methods.

关键词： Trefftz boundary element, point-collocation technique, Galerkin technique, special trial function anti-plane fracture, piezoelectric medium

Helical Fiber Pull-out in Biological Materials

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Acta Mechanica Solida Sinica 2016年第3期29卷 245-256页

作者： Lixin Wang Yuhong Cui qinghua qin Hui Wang Jianshan Wang Tianjin Key Laboratory of Modern Engineering Mechanics & Department of Mechanics Tianjin University Research School of Engineering Australian National University Department of Engineering Mechanics Henan University of Technology

Many biological materials, such as wood and bone, possess helicoid microstructures at microscale, which can serve as reinforcing elements to transfer stress between crack surfaces and improve the fracture toughness of their composites. Failure processes, such as fiber/matrix inter- face debonding and sliding associated with pull-out of helical fibers, are responsible mainly for the high energy dissipation needed for the fracture toughness enhancement. Here we present systemic analyses of the pull-out behavior of a helical fiber from an elastic matrix via the finite element method （FEM） simulation, with implications regarding the underlying toughening mechanism of helicoid microstructures. We find that, through their uniform curvature and torsion, helical fibers can provide high pull-out force and large interface areas, resulting in high energy dissipation that accounts, to a large extent, for the high toughness of biological materials. The helicity of fiber shape in terms of the helical angle has significant effects on the force-displacement relationships as well as the corresponding energy dissipation during fiber pull-out.

关键词： biological materials helicoid microstructures fiber pull-out energy dissipation,toughness

Modeling and Prediction for the thrust on EPB TBMs under different geological conditions by considering mechanical decoupling

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Science China(Technological Sciences) 2016年第9期59卷 1428-1434页

作者： ZHANG Qian SU CuiXia qin qinghua CAI ZongXi HOU ZhenDe KANG YiLian Key Laboratory of Modern Engineering Mechanics Tianjin University Tianjin 300072 China China Railway Construction Heavy Industry Co. Ltd. Changsha 410100 China College of Engineering and Computer Science Australian National University Canberra ACT 0200 Australia

EPB TBMs(Earth pressure balance Tunneling Boring Machines) are extensively used in tunneling constructions because of its high efficiency and low disturbance on structures above ground. It is critically significant to predict the thrust acting on TBMs under different geological conditions for both the design of power system and the control of tunneling process. The interaction between the cutterhead and the ground is the core of excavation, through which geological conditions determine the thrust re-quirement combined with operating status and structural characteristics. This paper conducted a mechanical decoupling analysis to obtain a basic expression of the cutterhead-ground interactive stress. Then more engineering factors(such as cutterhead topological structure, underground overburden, thrusts on other parts, etc.) were further considered to establish a predicting model for the total thrust acting on a machine during tunneling. Combined with three subway projects under different geological conditions in China, the model was verified and used to analyze how geological, operating and structural parameters influence the acting thrust.

关键词： EPB TBMs thrust prediction different geological conditions mechanical decoupling