1.

3D FINITE ELEMENTANALYSIS OF THE DAMAGE EFFECTS ON THE DENTAL COMPOSITE SUBJECT TO WATER SORPTION





Fan Jianping Tsui C.P. Tang C.Y. Chow C.L.《Acta Mechanica Solida Sinica》,2006年第19卷第3期


The damage effects of water sorption on the mechanical properties of the hydroxyapatite particle reinforced BisGMA/TEGDMA copolymer (HA/BisGMA/TEGDMA) have been predicted using 3D finite cell models. The plasticizer effect on the polymer matrix was considered as a variation of its Young's modulus. Three different cell models were used to determine the influence of varying particle contents, interphase strength and moisture concentration on the debonding damage. The stress distribution pattern has been examined and the stress transfer mode clarified. The Young's modulus and fracture strength of the BisGMA/TEGDMA composite were also predicted using the model with and without consideration of the damage. The former results with consideration of the debonding damage are in good agreement with existing literature experimental data. The shielding effect of our proposed model and an alternative approach were discussed. The FCC cell model has also been extended to predict the critical load for the damaged and the undamaged composite subject to the 3point flexural test.

2.

MESOMECHANICAL ANALYSIS OF SHAPE MEMORY ALLOY REINFORCED SMART STRUCTURE WITH DAMAGE





Hu Zili《Acta Mechanica Solida Sinica》,2006年第19卷第3期


The mechanical behaviors of shape memory alloy (SMA) wires reinforced smart structure with damage were analyzed through the variational principle, a governing equation for the structure was derived, mathematical expressions for the mesodisplacement field, stressstrain field of typical element with damage were presented, and a failure criterion for interface failure between SMA wires and matrix was established under two kinds of actuation which are deadload and temperature, where the temperature is included in effective free restoring strain. In addition, there are some other composing factors in the failure criterion such as the interface properties, dynamical properties of SMA, initial debonding length Ll etc. The results are significant to understand structural strength selfadapted control and failure mechanism of SMA wires reinforced smart structure with damage.

3.

Precracking and interfacial delamination in a bimaterial structure:Static and dynamic loadings





Barbara Gambin Jordanka Ivanova Varbinka Valeva Gergana Nikolova《Acta Mechanica Sinica》,2011年第27卷第1期


The behavior of a precracked bimaterial structure interface under given static and dynamic axial loading is an interest object in the present paper.Firstly,it is shown that the shearlag model is a proper tool to analyze a delamination process in a precracked bimaterial structure undergoing static loading.Secondly,the"shearlag model"is applied to the structure under dynamic loading.To solve the problem for an interface delamination of the structure and to determine the debond length along the interface,our own 2D boundary element method(BEM)code is proposed in the case of static loading,and the shearlag model together with the Laplace transforms and halfanalytical calculations are used in the case of dynamic loading.The interface layer is assumed as a very thin plate compared with the other two.The parametric(geometric and elastic)analysis of the debond length and interface shear stress is done. The results from the 2D BEM code proved the validity of analytical solutions to the shearlag model.In the dynamic case,the influence of loading characteristics,i.e.,frequencies and amplitude fluctuations on the shear stress and the value of debond length for an interval of time,is discussed. The analysis of the obtained results is illustrated by an example of the modern ceramicmetal composite,namely cermet, and depicted in figures.

4.

BIOMECHANICAL MODELING OF SURFACE WRINKLING OF SOFT TISSUES WITH GROWTHDEPENDENT MECHANICAL PROPERTIES





Yanping Cao Yi Jiang Bo Li Xiqiao FengInstitute of Biomechanics and Medical Engineering《Acta Mechanica Solida Sinica》,2012年第5期


This paper explores growth induced morphological instabilities in biological soft materials.In view of that the growth of a living tissue not only changes its geometry but also can alter its mechanical properties,we suggest a refined volumetric growth model incorporating the effects of growth on the mechanical properties of materials.Analogy between this volumetric growth model and the conventional thermal stress model is addressed for both small and finite deformation problems,which brings great ease for the finite element analysis based on the suggested model.Examples of growth induced surface wrinkling behavior in soft composites,including coreshell soft cylinders and threelayered soft tissues,are explored.The results and discussions foresee possible applications of the model in understanding the correlation between the morphogenesis and growth of soft biological tissues(e.g.skins and tumors),as well as in evaluating the deformation and surface instability behavior of soft artificial materials induced by swelling/shrinkage.

5.

Sizedependent thermal stresses in the core–shell nanoparticles





Astefanoaei I Dumitru I Stancu Al《中国物理 B》,2013年第12期


The thermal stress in a magnetic core–shell nanoparticle during a thermal process is an important parameter to be known and controlled in the magnetization process of the core–shell system. In this paper we analyze the stress that appears in a core–shell nanoparticle subjected to a cooling process. The external surface temperature of the system, considered in equilibrium at room temperature, is instantly reduced to a target temperature. The thermal evolution of the system in time and the induced stress are studied using an analytical model based on a timedependent heat conduction equation and a differential displacement equation in the formalism of elastic displacements. The source of internal stress is the difference in contraction between core and shell materials due to the temperature change. The thermal stress decreases in time and is minimized when the system reaches the thermal equilibrium. The radial and azimuthal stress components depend on system geometry, material properties, and initial and final temperatures. The magnitude of the stress changes the magnetic state of the core–shell system. For some materials, the values of the thermal stresses are larger than their specific elastic limits and the materials begin to deform plastically in the cooling process. The presence of the induced anisotropy due to the plastic deformation modifies the magnetic domain structure and the magnetic behavior of the system.

6.

CONSOLIDATION HEORY OF UNSATURATED SOIL BASED ON THE THEORY OF MIXTURE(Ⅰ)





陈正汉 谢定义 刘祖典《应用数学和力学(英文版)》,1993年第2期


Unsaturated soil is a threephase media and is composed of soil grain,water andgas.In this paper,the consolidation problem of unsaturated soil is investigated basedon the theory of mixture.A theoretical formula of effective stress on anisotropicporous media and unsaturated soil is derived.The principle of effective stress and theprinciple of Curie symmetry are taken as two fundamental constitutive principles ofunsaturated soil.A mathematical model of consolidation of unsaturated soil isproposed,which consists of25 partial differenfial equations with25 unknowns.Withthe help of increament linearizing method,the model is reduced to5 governingequations with5 unknowns,i.e.,the three displacement components of solid phase,thepore water pressure and the pore gas pressure.7 material parameters are involved inthe model and all of them can be measured using soil tests.It is convenient to use themodel to engineering practice.The well known Biot’s theory is a special case of themodel.

7.

CONSOLIDATION HEORY OF UNSATURATED SOIL BASED ON THE THEORY OF MIXTURE(Ⅰ)





Chen Zhenghan Xie Dingyi Liu Zudian《应用数学和力学(英文版)》,1993年第14卷第2期


Unsaturated soil is a threephase media and is composed of soil grain, water and gas. In this paper, the consolidation problem of unsaturated soil is investigated based on the theory of mixture. A theoretical formula of effective stress on anisotropic porous media and unsaturated soil is derived. The principle of effective stress and the principle of Curie symmetry are taken as two fundamental constitutive principles of unsaturated soil. A mathematical model of consolidation of unsaturated soil is proposed, which consists of 25 partial differenfial equations with 25 unknowns. With the help of increament linearizing method, the model is reduced to 5 governing equations with 5 unknowns, i.e., the three displacement components of solid phase, the pore water pressure and the pore gas pressure. 7 material parameters are involved in the model and all of them can he measured using soil tests. It is convenient to use the model to engineering practice. The well known Biot’s theory is a special case of the model.

8.

ANALYTICAL ANALYSIS OF INTERFACIAL STRESSES IN FRPRC HYBRID BEAMS WITH TIMEDEPENDENT DEFORMATIONS OF RC BEAM





Bouazza Fahsi Kouider Halim Benrahou Baghdad Krour Abdeloauhed Tounsi Samir Benyoucef1 E Abbas Adda Bedia《Acta Mechanica Solida Sinica》,2011年第6期


In this paper, the effect of timedependent deformations (such as shrinkage and creep) on the interfacial stresses between an RC beam and FRP plate is presented. For this end, a closedform solution for such stresses in externally FRP plated RC beams including creep and shrinkage effects is presented. The developed model is formulated to predict the interfacial stresses at time ‘t’, in which the RC beams have been already subjected to creep and shrinkage effects. The adherend shear deformations have been included in the present theoretical analysis by assuming a parabolic shear stress through the thickness of the RC beam and the FRP panel. Contrary to some existing studies, the assumption that both RC beam and FRP panel have the same curvature is not used in the present investigation. This research is helpful for the understanding on mechanical behavior of the interface and design of the FRPRC hybrid structures.

9.

Effective viscoelastic behavior of particulate polymer composites at finite concentration 被引次数：2





李丹 胡更开《应用数学和力学(英文版)》,2007年第28卷第3期


Polymeric materials usually present some viscoelastic behavior. To improve the mechanical behavior of these materials, ceramics materials are often filled into the polymeric materials in form of fiber or particle. A micromechanical model was proposed to estimate the overall viscoelastic behavior for particulate polymer composites, especially for high volume concentration of filled particles. The method is based on Laplace transform technique and an elastic model including twoparticle interaction. The effective creep compliance and the stress and strain relation at a constant loading rate are analyzed. The results show that the proposed method predicts a significant stiffer response than those based on MoriTanaka's method at high volume concentration of particles.

10.

Micromechanical analysis of the behavior of stiff clay





Ching S.Chang PierreYves Hicher《Acta Mechanica Sinica》,2011年第27卷第6期


Cementations formed in geological timescale are observed in various stiff clays.A micromechanical stress strain model is developed for modeling the effect of cementation on the deformation behavior of stiff clay.The proposed approach considers explicitly cementations at intercluster contacts,which is different from conventional model.The concept of intercluster bonding is introduced to account for an additional cohesion in shear sliding and a higher yield stress in normal compression.A damage law for intercluster bonding is proposed at cluster contacts for the debonding process during mechanical loading.The model is used to simulate numerous stresspath tests on Vallericca stiff clay.The applicability of the present model is evaluated through comparisons between the predicted and the measured results.In order to explain the stressinduced anisotropy arising from externally applied load,the evolution of local stresses and local strains at intercluster planes are discussed.

11.

A macroscopic constitutive model of shape memory alloy considering cyclic effects





ZHOU Bo YOON SungHo《中国科学:物理学 力学 天文学(英文版)》,2013年第4期


This paper presents a macroscopic constitutive model reproducing the hysteretic behaviors of the superelastic shape memory alloy (SMA) under cyclic loading. The progressive increase of residual strain with the increased cycle number in such materials is assumed to be a consequence of the progressive increase of residual stressinduced martensitic volume fraction upon the cyclic effects. The progressive decrease of phase transformation critical stresses with the increased cycle number in such materials is assumed to be a result from the progressive increase of phase transformation critical temperatures upon the cyclic effects. A cyclic evolution equation is supposed to describe the influences of cycle effects on the material properties of the SMA under cyclic loading. A phase transformation equation expressing the phase transformation behaviors of the SMA under cyclic loading is established based on the differential relationship between martensitic volume fraction and the free energy increment of phase transformation. A mechanical constitutive equation predicting the mechanical characteristics of the SMA under cyclic loading is developed on the basis of thermodynamics and continuum mechanics. The cyclic evolution equation, phase transformation equation, and mechanical constitutive equation together compose the presented macroscopic constitutive model considering cyclic effects. Results of the numerical simulations illustrate that it can well reproduce the superelastic hysteretic behaviors of the SMA under cyclic loading.

12.

Numerical analysis of theoretical model of the RF MEMS switches 被引次数：4





张立宪 余同希 赵亚溥《Acta Mechanica Sinica》,2004年第20卷第2期


An improved electromechanical model of the RF MEMS (radio frequency microelectromechanical systems) switches is introduced, in which the effects of intrinsic residual stress from fabrication processes, axial stress due to stretching of beam， and fringing field are taken into account. Four dimensionless numbers are derived from the governing equation of the developed model. A semianalytical method is developed to calculate the behavior of the RF MEMS switches. Subsequently the influence of the material and geometry parameters on the behavior of the structure is analyzed and compared, and the corresponding analysis with the dimensionless numbers is conducted too. The quantitative relationship between the presented parameters and the critical pullin voltage is obtained, and the relative importance of those parameters is given.

13.

The effect of laser beam size on laserinduced damage performance





韩伟 王芳 周丽丹 冯斌 贾怀庭 李恪宇 向勇 郑万国《中国物理 B》,2012年第21卷第7期


The influence of laser beam size on laserinduced damage performance, especially damage probability and the laserinduced damage threshold (LIDT), is investigated. It is found that damage probability is dependent on beam size when various damage precursors with different potential behaviors are involved. This causes the damage probability and the LIDT to be different between cases under a largeaperture beam and a smallaperture beam. Moreover, the fluence fluctuation of the largeaperture laser beam brings out hot spots, which move randomly across the beam from shot to shot. Thus this leads the most probable maximum fluence after many shots at any location on the optical component to be several times the average beam fluence. These two effects result in the difference in the damage performance of the optical component between the cases under a largeaperture and smallaperture laser.

14.

THEORETICAL MODEL ON INTERFACE FAILURE MECHANISM OF REINFORCED CONCRETE CONTINUOUS BEAM STRENGTHENED BY FRP





Hong Yuan Zifeng Lin《Acta Mechanica Solida Sinica》,2009年第22卷第2期


Fiber reinforced polymer （FRP） composites are increasingly being used for the repair and strengthening of deteriorated concrete structural components through adhesive bonding of prefabricated strips/plates and the wet layup of fabric. Interfacial bond failure modes have attracted the attention of researchers because of the importance. The objective of the present study is to analyse the interface failure mechanism of reinforced concrete continuous beam strengthened by FRP. An analytical solution has been firstly presented to predict the entire debonding process of the model. The realistic bilinear bondslip interfacial law was adopted to study this problem. The crack propagation process of the loaded model was divided into four stages （elastic,elasticsoftening,elasticsofteningdebonded and softeningdebonded stage）. Among them,elasticsofteningdebonded stage has four substages. The equations are solved by adding suitable stress and displacement boundary conditions. Finally,critical value of bond length is determined to make the failure mechanism in the paper effective by solving the simultaneously linear algebraic equations. The interaction between the upper and lower FRP plates can be neglected if axial stiffness ratio of the concretetoplate prism is large enough.

15.

Finite element method for viscoelastic medium with damage and the application to structural analysis of solid rocket motor grain





DENG Bin SHEN ZhiBin DUAN JingBo TANG GuoJin《中国科学:物理学 力学 天文学(英文版)》,2014年第57卷第5期


This paper studies the damageviscoelastic behavior of composite solid propellants of solid rocket motors(SRM).Based on viscoelastic theories and strain equivalent hypothesis in damage mechanics,a threedimensional(3D)nonlinear viscoelastic constitutive model incorporating with damage is developed.The resulting viscoelastic constitutive equations are numerically discretized by integration algorithm,and a stressupdating method is presented by solving nonlinear equations according to the NewtonRaphson method.A material subroutine of stressupdating is made up and embedded into commercial code of Abaqus.The material subroutine is validated through typical examples.Our results indicate that the finite element results are in good agreement with the analytical ones and have high accuracy,and the suggested method and designed subroutine are efficient and can be further applied to damagecoupling structural analysis of practical SRM grain.

16.

BRIDGETOUGHENING ANALYSIS OF THE FIBER REINFORCED COMPOSITE CONTAINING INTERPHASE EFFECT





Wu Zhangjian Yu Shouwen《Acta Mechanica Solida Sinica》,1994年第7卷第1期


A detailed fracture mechanics analysis of bridgetoughening in a fiberreinforced composite is presented in this paper.The integral equation governing bridgetoughening as well as crack opening displacement (COD) for the composite withinterfacial layer is derived from the Castigliano's theorem and interface shearlagmodel.A numerical result of the COD equation is obtained using the iteration solutionof the second Fredholm integral equation.In order to investigate the effect of variousparameters on the toughening,an approximate analytical solution of the equation ispresent and its error analysis is performed,which demonstrates the approximatesolution to be appropriate.A parametric study of the influence of the crack length,interracial shear modules,thickness of the interphase,fiber radius,fiber volumefraction and properties of materials on composite toughening is therefore carried out.The results are useful for experimental demonstration and toughening design includingthe fabrication process of the composite.

17.

SCATTERING OF HARMONIC ANTIPLANE SHEAR STRESS WAVES BY A CRACK IN FUNCTIONALLY GRADED PIEZOELECTRIC/PIEZOMAGNETIC MATERIALS





Liang Jun《Acta Mechanica Solida Sinica》,2007年第20卷第1期


In this paper, the dynamic behavior of a permeable crack in functionally graded piezoelectric/piezomagnetic materials is investigated. To make the analysis tractable, it is assumed that the material properties vary exponentially with the coordinate parallel to the crack. By using the Fourier transform, the problem can be solved with the help of a pair of dual integral equations in which the unknown is the jump of displacements across the crack surfaces. These equations are solved to obtain the relations between the electric filed, the magnetic flux field and the dynamic stress field near the crack tips using the Schmidt method. Numerical examples are provided to show the effect of the functionally graded parameter and the circular frequency of the incident waves upon the stress, the electric displacement and the magnetic flux intensity factors of the crack.

18.

An energyequilibrium model for complex stress effect on fatigue crack initiation





ZHAO SiCong XIE JiJia ZHAO AiGuo WU XiaoLei《中国科学:物理学 力学 天文学(英文版)》,2014年第57卷第5期


Based on Tanaka and Mura’s fatigue model and Griffith theory for fracture,an energyequilibrium model was proposed to explain the complex stress effect on fatigue behavior.When the summation of the elastic strain energy release and the stored strain energy of accumulated dislocations reach the surface energy of a crack,the fatigue crack will initiate in materials.According to this model,for multiaxial stress condition,the orientation of the crack initiation and the initiation life can be deduced from the energy equilibrium equation.For the uniaxial fatigue loading with mean stress,the relation between the maximum stress or the minimum stress and the stress amplitude is in agreement with an ellipse equation on the constant life diagram.If the ratio of the mean stress to stress amplitude is less than a critical value0.17,and the stress amplitude keeps constant,the fatigue crack initiation life will decrease with the increase of the compress mean stress.In this model,the mean stress does not cause damage accumulation with the fatigue cycles in crack initiation.For this reason,the loading sequence of different load levels would induce the cumulative damage to deviate from the PalmgrenMiner cumulative damage rule.The procedure of estimating the damage under random loading is also discussed.

19.

DYNAMIC ANALYSIS OF A BURIED RIGID ELLIPTIC CYLINDER PARTIALLY DEBONDED FROM SURROUNDING MATRIX UNDER SHEAR WAVES 被引次数：2





Wang Yuesheng Wang Duo Department of Astronautics and Mechanics Harbin Institute of Technology Harbin 150001 P. R. China《Acta Mechanica Solida Sinica》,1995年第8卷第1期


This paper investigates the dynamic behavior of a buried rigid ellipticcylinder partially debonded from surrounding matrix under the action of antiplaneshear waves (SH waves). The debonding region is modeled as an elliptic arcshapedinterface crack with noncontacting faces. By using the wave function (Mathieufunction) expansion method and introducing the dislocation density function as anunknown variable, the problem is reduced to a singular integral equation which issolved numerically to calculate the near and far fields of the problem. The resonanceof the structure and the effects of various parameters on the resonance are discussed.

20.

Numerical simulation and control of welding distortion for double floor structure of high speed train





WenChao Dong ShanPing Lu Hao Lu DianZhong Li LiJian Rong YiYi Li《Acta Mechanica Sinica》,2014年第6期


The welding heat source models and the plastic tension zone sizes of a typical weld joint involved in the double floor structure of high speed train under different welding parameters were calculated by a thermalelasticplastic FEM analysis based on SYSWELD code.Then,the welding distortion of floor structure was predicted using a linear elastic FEM and shrinkage method based on Weld Planner software.The effects of welding sequence,clamping configuration and reverse deformation on welding distortion of floor structure were examined numerically.The results indicate that the established elastic FEM model for floor structure is reliable for predicting the distribution of welding distortion in view of the good agreement between the calculated results and the measured distortion for real double floor structure.Compared with the welding sequence,the clamping configuration and the reverse deformation have a significant influence on the welding distortion of floor structure.In the case of30 mm reverse deformation,the maximum deformation can be reduced about 70%in comparison to an actual welding process.
