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A hybrid-stress solid-shell element for non-linear analysis of piezoelectric structures

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中国科学:技术科学 2010年第3期 322-322页

作者： sze k y Department of Mechanical Engineering University of Hong Kong

This paper presents eight-node solid-shell elements for geometric non-linear analyze of piezoelectric *** subdue shear,trapezoidal and thickness locking,the assumed natural strain method and an ad hoc modified generalized laminate stiffness matrix are *** the generalized stresses arising from the modified generalized laminate stiffness matrix assumed to be independent from the ones obtained from the displacement,an extended Hellinger-Reissner functional can be *** choosing the assumed generalized stresses similar to the assumed stresses of a previous solid element,a hybrid-stress solid-shell element is *** presented finite shell element is able to model arbitrary curved shell ***-linear numerical examples demonstrate the ability of the proposed model to analyze nonlinear piezoelectric devices.

关键词： piezoelectric structures solid-shell element hybrid-stress geometric non-linear

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双压电材料界面力电耦合场奇异性研究

工程力学 2006年第1期23卷 165-171页

作者：王海涛佘锦炎华南理工大学土木工程系广东广州510640 香港大学机械工程系

针对不同压电材料中界面裂纹尖端的扇形区域推导出了包含基本方程、裂纹面D-P边界条件和不同压电材料交界面处的边界条件的弱形式。在该弱形式的基础上,利用特征方程展开方法(eigenfunction expansion technique),可以得到一个分析压电... 详细信息

针对不同压电材料中界面裂纹尖端的扇形区域推导出了包含基本方程、裂纹面D-P边界条件和不同压电材料交界面处的边界条件的弱形式。在该弱形式的基础上,利用特征方程展开方法(eigenfunction expansion technique),可以得到一个分析压电材料裂纹尖端处力电耦合场奇异性的特殊的一维有限元列式。该一维有限元列式只需对扇形区域在角度方向上离散,最后的总体方程为一个二次特征根方程。求解该特征根方程就可以得到压电材料裂纹尖端处力电耦合奇异场的特征解。通过数值算例表明该方法可以准确而高效地计算压电材料裂纹尖端处力电耦合奇异场的特征解,进而用该方法研究了双压电材料界面力电耦合场的奇异性。

关键词：压电材料双压电材料奇异性有限元裂纹

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以优化方法求解布料无摩擦接触变形问题

固体力学学报 2005年第4期26卷 482-484页

作者：刘小虎佘锦炎王乘华中科技大学力学系武汉430074 香港大学机械工程系

利用作者所提出的布料质点模型,用罚函数法解除布料和其它物体之间的接触约束,把接触约束条件下的极值问题转化为无约束极值问题,用F-R共轭梯度法求解,并用三次插值方法进行一维搜索.计算了有缝摺和裁剪开口的布料与球形物体的接触变形... 详细信息

利用作者所提出的布料质点模型,用罚函数法解除布料和其它物体之间的接触约束,把接触约束条件下的极值问题转化为无约束极值问题,用F-R共轭梯度法求解,并用三次插值方法进行一维搜索.计算了有缝摺和裁剪开口的布料与球形物体的接触变形问题,得到的结果符合人们的日常实际观察.

关键词：布料接触变形共轭梯度

HyBRID LINEAR AND QUADRATIC FINITE ELEMENT MODELS FOR 3D HELMHOLTZ PROBLEMS

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Acta Mechanica Solida Sinica 2013年第6期26卷 603-618页

作者： Q.H.Zhang k.y.sze Guangdong Province key Laboratory of Computational Science Sun Yat-Sen University Department of Mechanical Engineering The University of Hong KongPokfulam

In this paper, linear and quadratic finite element models are devised for the three- dimensional Helmholtz problem by using a hybrid variational functional. In each element, contin- uous and discontinuous Helmholtz fields are defined with their equality enforced over the element boundary in a weak sense. The continuous field is based on the C° nodal interpolation and the discontinuous field can be condensed before assemblage. Hence, the element can readily be in- corporated seamlessly into the standard finite element program framework. Discontinuous fields constructed by the plane-wave, Bessel and singular spherical-wave solutions are attempted. Nu- merical tests demonstrate that some of the element models are consistently and considerably more accurate than their conventional counterparts.

关键词： finite element hybrid Helmholtz Bessel plane-wave spherical-wave radial basis function

A hyperbolic Lindstedt-Poincare method for homoclinic motion of a kind of strongly nonlinear autonomous oscillators

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Acta Mechanica Sinica 2009年第5期25卷 721-729页

作者： y.y.Chen S.H.Chen k.y.sze Department of Applied Mechanics and Engineering Sun yat-sen University Department of Mechanical Engineering The University of Hong Kong Department of Applied Mechanics and Engineering Sun Yat-sen University

A hyperbolic Lindstedt-Poincare method is presented to determine the homoclinic solutions of a kind of nonlinear oscillators, in which critical value of the homoclinic bifurcation parameter can be determined. The generalized Lienard oscillator is studied in detail, and the present method＇s predictions are compared with those of Runge-kutta method to illustrate its accuracy.

关键词： Lindstedt-Poincare method Hyperbolic function Nonlinear autonomous oscillator - Homoclinic orbit

An Adjustable Pure Dispersion Slope Compensating-Module without Center Wavelength Shift Based on Strain-Chirped Fiber Bragg Gratings

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光学学报 2003年第S1期23卷 131-132页

作者： Chee S. Goh sze y. Set k. kikuchi RCAST University of Tokyo 4-6-1 Komaba Meguro-ku Tokyo 153-8904 JapanAlnair Labs Corporation 6-3-14 Kawaguchi Kawaguchi city Saitama-ken 332-0015 JapanRCAST University of Tokyo 4-6-1 Komaba Meguro-ku Tokyo 153-8904 Japan Alnair Labs Corporation 6-3-14 Kawaguchi Kawaguchi city Saitama-ken 332-0015 Japan

We demonstrate an adjustable pure dispersion slope compensating-module based on strain-chirped fiber Bragg gratings. The center wavelength of the module is preserved while the pure dispersion slope is tuned.

关键词： FBG be on An Adjustable Pure Dispersion Slope Compensating-Module without Center Wavelength Shift Based on Strain-Chirped Fiber Bragg Gratings of in DS

Homoclinic and heteroclinic solutions of cubic strongly nonlinear autonomous oscillators by hyperbolic Lindstedt-Poincaré method

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Science China(Technological Sciences) 2010年第3期53卷 692-702页

作者： sze kam yim Department of Mechanical Engineering The University of Hong Kong

The hyperbolic Lindstedt-Poincaré method is applied to determine the homoclinic and heteroclinic solutions of cubic strongly nonlinear oscillators of the form x + c1 x + c3 x 3= ε f (μ,x,x).In the method,the hyperbolic functions are employed instead of the periodic functions in the Lindstedt-Poincaré *** value of parameter μ under which there exists homoclinic or heteroclinic orbit can be determined by the perturbation *** applications are studied in *** illustrate the accuracy of the present method,its predictions are compared with those of Runge-kutta method.

关键词： Lindstedt-Poincaré Method nonlinear autonomous oscillator homoclinic orbit heteroclinic orbit

Microcurvature landscapes induce neural stem cell polarity and enhance neural differentiation

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Bio-Design and Manufacturing 2023年第5期6卷 522-535页

作者： Ho-yin yuen Wai-sze yip Suet To Xin Zhao Department of Biomedical Engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong Kong SARChina State key Laboratory of Ultra-Precision Machining Technology Department of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityHung HomKowloonHong Kong SARChina

Tissue curvature has long been recognized as an important anatomical parameter that affects intracellular behaviors,and there is emerging interest in applying cell-scale curvature as a designer property to drive cell fates for tissue engineering *** neural cells are known to undergo dramatic and terminal morphological changes during development and curvature-limiting behaviors have been demonstrated in neurite outgrowth studies,there are still crucial gaps in understanding neural cell behaviors,particularly in the context of a three-dimensional(3D)curvature landscape similar to an actual tissue engineering *** this study,we fabricated two substrates of microcurvature(curvature-substrates)that present a smooth and repeating landscape with focuses of either a concave or a convex *** these curvature-substrates,we studied the properties of morphological differentiation in N2a neuroblastoma *** contrast to other studies where two-dimensional(2D)curvature was demonstrated to limit neurite outgrowth,we found that both the concave and convex substrates acted as continuous and uniform mechanical protrusions that significantly enhanced neural polarity and differentiation with few morphological changes in the main cell *** enhanced differentiation was manifested in various properties,including increased neurite length,increased nuclear displacement,and upregulation of various neural *** demonstrating how the micron-scale curvature landscape induces neuronal polarity,we provide further insights into the design of biomaterials utilizing the influence of surface curvature in neural tissue engineering.

关键词： Curvature Neural differentiation Neurite outgrowth Mechanotransduction

Advancing Nitinol: From heat treatment to surface functionalization for nickel-titanium (NiTi) instruments in endodontics

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Bioactive Materials 2023年第4期22卷 91-111页

作者： Wai-sze Chan karan Gulati Ove APeters The University of Queensland School of DentistryHerstonQLD4006Australia

Nickel-titanium(NiTi)alloy has been extensively researched in endodontics,particularly in cleaning and shaping the root canal *** advances have primarily focused on the design,shape,and geometry of the NiTi files as well as metallurgy and mechanical *** far,extensive investigations have been made surrounding surface and thermomechanical treatments,however,limited work has been done in the realm of surface functionalization to augment its performance in *** review summarizes the unique characteristics,current use,and latest developments in thermomechanically treated NiTi endodontic *** discusses recent improvements in nano-engineering and the possibility of customizing the NiTi file surface for added *** clinical translation of this technology has yet to be fully realized,future research direction will lie in the use of nanotechnology.

关键词： Nitinol Endodontics Nickel Titanium Nanostructures