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Basic solution of two parallel Mode-I cracks in functionally graded materials

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Science china(Technological Sciences) 2008年第9期51卷 1380-1393页

作者： liang jun center for composite materials and structures, harbin Institute of {2., harbin 150080, china center for composite {2. and structures Harbin Institute of Technology Harbin 150080 China

The solution of two parallel cracks in functionally graded materials subjected to a tensile stress loading is derived in this paper. To make the analysis tractable, it is assumed that the shear modulus varies exponentially with coordinate parallel to the crack. The problem is formulated through Fourier transform into four pairs of dual integral equations, in which the unknown variables are jumps of displace-ments across crack surfaces. To solve the dual integral equations, the jumps of displacements across crack surfaces are directly expanded as a series of Jacobi polynomials to obtain the shielding effects of the two parallel cracks in functionally graded materials.

关键词： parallel cracks shielding effects functionally graded materials

The nonlocal solution of two parallel cracks in functionally graded materials subjected to harmonic anti-plane shear waves

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Acta Mechanica Sinica 2007年第4期23卷 427-435页

作者： jun liang Shiping Wu Shanyi Du {2. for composite materials and Structure,harbin Institute of technology,harbin 150001,china center for composite {2. and Structure Harbin Institute of Technology Harbin 150001 China

In this paper, the dynamic interaction of two parallel cracks in functionally graded materials （FGMs） is investigated by means of the non-local theory. To make the analysis tractable, the shear modulus and the material density are assumed to vary exponentially with the coordinate vertical to the crack. To reduce mathematical difficulties, a one-dimensional non-local kernel is used instead of a twodimensional one for the dynamic problem to obtain stress fields near the crack tips. By use of the Fourier transform, the problem can be solved with the help of two pairs of dual integral equations, in which the unknown variables are the jumps of displacements across the crack surfaces. To solve the dual integral equations, the jumps of displacements across the crack surfaces are expanded in a series of Jacobi polynomials. Unlike the classical elasticity solutions, it is found that no stress singularity is present at the crack tips. The non-local elastic solutions yield a finite hoop stress at the crack tips. The present result provides theoretical references helpful for evaluating relevant strength and preventing material failure of FGMs with initial cracks. The magnitude of the finite stress field depends on relevant parameters, such as the crack length, the distance between two parallel cracks, the parameter describing the FGMs, the frequency of the incident waves and the lattice parameter of materials.

关键词： Crack The non-local theory Stress waves Functionally graded materials

Effects of heat treatment on mechanical properties of ODS nickel-based superalloy sheets prepared by EB-PVD

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Rare Metals 2011年第1期30卷 76-80页

作者： CHEN Song QU Shoujiang liang jun HAN Jiecai center for composite {2. Harbin Institute of TechnologyHarbin 150001China

A Y2.3 dispersion strengthened nickel-based superalloy sheet（0.15 mm thick） was prepared by electron beam physical vapor deposition（EB-PVD） *** heat treatments were used to improve the mechanical properties of the alloy *** thermal analysis（DTA） was used to examine the thermal stability of the as-deposited *** contents,phase composition and microstructure investigations on as-deposited and heat treated specimens were performed by X-ray fluorescence spectrometer（XRF）,X-ray diffraction（XRD） and scanning electron microscopy（SEM）.Tensile tests were conducted at room temperature on specimens as-deposited and heat *** results show that the as-deposited sheet is composed of equiaxed grains on the substrate side and columnar grains on the evaporation *** as-deposited sheet shows poor ductility due to micropores between columnar *** strength and ductility can be improved effectively by annealing at 800°C for 3 *** samples treated at 1100°C,the strength drops down due to the precipitates of Y3Al5O12.YAG）.

关键词： superalloys nickel alloys mechanical properties heat treatment electron beams physical vapor deposition

Enhanced thermoelectric performance enabled by compositing ZrO_(2.in n-type SiGe alloy with low thermal conductivity

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Rare Metals 2024年第3期43卷 1167-1176页

作者： Meng-Fei Wang Hua-jun Lai Ji-Sheng liang jun-liang Chen Wang-Yang Ding Qi Zhou Ying Peng Cheng-Yan Liu Lei Miao Guangxi Key Laboratory for Relativity Astrophysics State Key Laboratory of Featured Metal Materials and Life-Cycle Safety for Composite StructuresSchool of Physical Science and TechnologyGuangxi UniversityNanning530004China Guangxi Academy of Sciences Nanning530007China Key Laboratory of Information Material Engineering Research Center of Electronic Information Materials and DevicesGuilin University of Electronic TechnologyMinistry of EducationGuilin541004China Guangxi Key Laboratory of Precision Navigation technology and Application School of Information and CommunicationGuilin University of Electronic TechnologyGuilin541004China

SiGe-based thermoelectric(TE)materials have gained increasing interests due to their low maintenance costs,environmental friendliness and long ***,the intrinsically high thermal conductivity of Si-based materials also results in poor TE *** this investigation,a zirconia(ZrO_(2.){2. strategy was applied to an n-type SiGe alloy,tremendously elevating its TE *** mechanical alloying and spark plasma sintering(SPS)processes,the ZrO_(2.induced the formation of nanopores in the SiGe matrix via phosphorus ***,such increase in porosity enhanced the phonon scattering and dramatically suppressed lattice thermal conductivity,from 2.83 to 1.59 W·m^(-1)·K^(-1)at 873 ***,reduced phosphorus doping led to an increase in Seebeck coefficients and a relatively minor decrease in electrical conductivity,The power factor didn't deteriorate significantly,either,as its maximum of~3.43 mW·m^(-1-)K^(-2.was achieved at 873 K with(Si_(0.8)Ge_(0.2.)_(0.097)P_(0.03)(ZrO_(2.)_(0.003).In short,a peak figure of merit(ZT)of~1.2. at 873 K and an average ZT~0.7 from 32. to 873 K were *** study demonstrates that the electrical and thermal transportation of SiGe material can be synergistically tuned by compositing ZrO_(2.,illustrating a novel strategy to optimize the TE properties of bulk materials.

关键词： Thermoelectric SiGe alloy ZrO2.composting P element adsorption nanopores

Mechanical Properties of Metal Honeycomb SandWich Panel

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Mechanical Properties of Metal Honeycomb SandWich Panel

Mesoscopic investigation on moduli prediction in visco-elastic particle reinforced composites

International Conference on Experimental Mechanics 2.08 (ICEM 2.08)

作者： Guangping Zou~(1 *) Jie Lu~1 jun liang~2.Zhongliang Chang~1 1 center for Mechanics Testing harbin Engineering University harbin china 2.center for composite materials harbin Institute of technology harbin china

＜正＞Many developed countries are committed to work with the aerospace industry to develop a Reusable Launch Vehicle（RLV） because it will greatly reduce the cost of repetition launching into *** space shuttle"Colum... 详细信息

关键词： MTPS mechanical properties digital speckle correlation method ESPI debonding detection

来源： cnki会议评论

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Mesoscopic investigation on moduli prediction in visco-elast...

ZrB_2.SiC复合陶瓷双尺度热应力分析

第五届国际非线性力学会议

作者： Bao-lai Wang~1 Yang Liu~1 jun liang~1 Shan-yi Du~1 ({2. for composite materials and Structure harbin Institute of technology harbin 150001 china)

＜正＞The visco-elastic mechanism of particles reinforced composites has been investigated through revised Eshelby equivalent inclusion theory.A visco-elastic model is applied. Furthermore,by introducing Heaviside step function and Laplace transform,the creep constitutional equation related to strain rate effect is ***,by equivalent inclusion theory,introducing secant modulus,the material moduli with time and volume fraction concerning Glass/ED6 particles reinforced materials have been *** results show that the visco-elastic property of composite material is mainly determined by the visco-elastic behavior of the matrix,which agree with experimental results *** can be concluded from the results that there exits close relationship between the inclusion shape,volume fraction and loading path.

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来源： cnki会议评论

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上海航天 2011年第4期28卷 67-72页

作者：唐绍锋梁军杜善义哈尔滨工业大学复合材料与结构研究所黑龙江哈尔滨150001

基于双尺度渐近分析方法,对ZrB2.SiC陶瓷的细观热应力场进行数值模拟,研究了SiC夹杂的含量、颗粒尺寸和中心距对细观ZrB2.SiC陶瓷单胞热应力场分布的影响。结果发现:在ZrB2.SiC陶瓷材料制备冷却过程中,SiC含量越高,材料越易产生微裂纹;... 详细信息

基于双尺度渐近分析方法,对ZrB2.SiC陶瓷的细观热应力场进行数值模拟,研究了SiC夹杂的含量、颗粒尺寸和中心距对细观ZrB2.SiC陶瓷单胞热应力场分布的影响。结果发现:在ZrB2.SiC陶瓷材料制备冷却过程中,SiC含量越高,材料越易产生微裂纹;当夹杂含量一定时,SiC夹杂颗粒的尺寸越大或夹杂颗粒间的中心距越小,材料越易产生微裂纹。数值计算结果与扫描电镜(SEM)照片吻合。

关键词：热应力双尺度渐近分析方法 ZrB2.SiC陶瓷细观

SCATTERING OF HARMONIC ANTI-PLANE SHEAR STRESS WAVES BY A CRACK IN FUNCTIONALLY GRADED PIEZOELECTRIC/PIEZOMAGNETIC materials

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Acta Mechanica Solida Sinica 2007年第1期20卷 75-86页

作者： liang jun P. O.Box 12.7 Center for Composite Materials Harbin Institute of Technology Harbin 150001 China

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.

关键词： functionally graded piezoelectric/piezomagnetic materials crack stress wave

Achieving thermal magnification by using effective thermal conductivity

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Theoretical & Applied Mechanics Letters 2018年第3期8卷 164-170页

作者： Qingxiang Ji Guodong Fang jun liang center for composite {2. Harbin Institute of Technology Institute of Advanced Structure technology Beijing Institute of Technology

thermal magnification device is proposed by using effective thermal conductivity. Different fromtransformation optics method, the magnification design is realized analytically by enforcingequality of effective thermal conductivity on the magnification device and the reference case inspecified domains. The validity of theoretical analysis is checked by numerical simulation results,which demonstrates the magnifying effects of the proposed design. The device only needsisotropic and homogeneous materials that are easy to obtain in nature. It is also shown that theobtained magnifying conditions are the same as those derived by separation of variables. But theproposed method proves more flexible for multilayered materials and simpler for non-sphericalobjects under non-uniform thermal fields. It can also be extended to other fields and applicationsgoverned by Laplace equation.

关键词： Thermal magnification Effective thermal conductivity Separation of variables