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Peridynamic simulations have been carried out to perform the slope stability analysis. A slope is first modelled with discretized particles in 2D. Then the non-ordinary state-based Peridynamic model is utilized. In order to obtain a more realistic behavior of the soil, Drucker-Prager constitutive model is used to describe the mechanic properties of soil. Results show great agreements with the FEM results, while provides the dynamic slide progress in the post-failure process.

The dynamic response of the square tube subjected to the impact of a mass was investigated by using experimental and numerical methods. The square tube was impacted by a mass at the velocity ranging from 5.09 m/s to 12.78 m/s, and different progressive buckling modes were obtained. The numerical simulation was also carried out to analyze the buckling mechanism of the square tube. The results show that there is obvious stress wave propagation and strain localization in the tube, which has a significant influence on the buckling mechanism of the tube. The stress wave and inertia of the mass play different roles at various impact velocities. And buckling mechanism at low velocity is mainly caused by stress wave, whereas the buckling mechanism at high velocity is resulted from the inertial of the mass.

The shear property of the thermoelectric material Bi2Te3is inextricably linked with its layer structure. By the molecular dynamics method, the mechanism of shearing deformation was studied in this paper. In the simulation, cubic single-crystal simulation cells with different layer directions inside were adopted, ensuring that thecaxis of crystal lattice can be along, across and 45odeviated from the shear stress. Compared with all the calculation models, the results show that when the shear stress increases, slip occurs along the Te1-Te1 adjacent layers which are connected by the weak van der Waals bonding, and ultimately leads to structural fracture. Furthermore, size effect and loading modes can also impact the behavior of shearing deformation, however, in very different ways. Future efforts should be focused on the influence of the creation and motion of defects during the deformation as well as temperature effect and strain rate effect.

Based on mark points on the surface of bridge pneumatic model, adopting the DIC-Digital image correlation method to handle the pictures captured by CCD Video Camera in the high frequency get the displacement values of the mark points in the time series and thus obtaining the vibration forms of the bridge. The fundamental principles of the DIC-Digital image correlation method and its application were introduced in this paper and the reliability and stability of the method was testified by the comparison to the results measured by the laser displacement sensor

In this article, the thermo-mechanical responses of ceramic/metal functionally graded thermal barrier coating(TBC) in work environment are analyzed by a finite element method. Both the crack-tip field and the stress intensity factor of functionally graded TBC are analyzed and calculated. It is discussed that the effect of crack length on mechanical properties of functionally graded TBC in the condition creep and no creep of pure metal. The numerical results indicate that the effect of crack length(a/t) is negligible to temperature distributions and the maximum displacements of whole model but remarkable to the 1st principal stress and stress intensity factor of crack region. Moreover, creep phenomenon of pure metal can relax the value of displacement, stress and stress intensity factor but do not alter their distribution.

In this paper the spline subdomain approach is applied to the 2D simulations of the temperature distributions for composites containing a single rectangular particle with an interfacial thermal resistance at the interface between the particle and matrix. The bicubic B-splines are used to construct the trial functions for the approximations of the potential fields of composites. Applying the weighted residual point collocation method inside each subdomain and also on the boundaries between different subdomains, a system of linear algebraic equations is set up to determine the unknowns of the trial functions. The temperature distributions both inside the rectangular particle and along the interfaces under different interfacial contact conditions can be simulated approximately. Numerical results which are compared with the available solutions obtained by FEM method illustrate the accuracy and suitability of the present approach for steady-state conduction. Even in the adjacent areas of corners in the rectangular particle, the simulation results are also satisfactory.

A new micromechanical method, the weighted residual self-consistent method (WRSCM) is developed to study the effective thermal conductivity of two-phase composites with different particle geometries in the presence of a thermal barrier resistance at the interface between constituents. The imperfect interface involves the continuity of the normal flux but allow for a finite temperature differences across the interface. Within the framework of self-consistent scheme, the effective thermal conductivity of two-phase composite is obtained using numerical iterative method on the basis of a surface integral of temperature over the imperfect interfaces. Numerical results show that for the given composite system, due to the existence of an interfacial thermal resistance, the particle geometries have significant impact on the effective thermal conductivity of composites.

This paper is aimed to numerically evaluate the effective thermal conductivity of randomly distributed spherical particle composite with imperfect interface between the constituents. A numerical homogenization technique based on the finite element method (FEM) with representative volume element (RVE) was used to evaluate the effective properties with periodic boundary conditions. Modified random sequential adsorption algorithm (RSA) is applied to generate the three dimensional RVE models of randomly distributed spheres of identical size with the volume fractions up to 50%. Several investigations have been conducted to estimate the influence of the imperfect interfaces on the effective conductivity of particulate composite. Numerical results reveal that for the given composite, due to the existence of an interfacial thermal barrier resistance, the effective thermal conductivity depends not only on the volume fractions of the particle but on the particle size.

The small punch creep (SP-C) test technique is a new method which is applied to evaluate the high temperature creep properties of materials by using miniature specimen. In the present paper, the Finite Element Method (FEM) is employed to simulate the SP-C test in order to investigate the effects of test parameters on testing results of the SP-C test. In this attempt, we perform systematic numerical simulations of SP-C tests by changing friction coefficient, specimen thickness, the diameter of punch ball and the inner diameter of lower die, and discuss the effects of the variation of test parameters on test results in detail. The resulting regression equations for assessing the effects of testing parameters on test results are obtained. It is found that the test results are influenced significantly by the specimen thickness, the diameter of punch ball and the inner diameter of lower die. However, the effects of friction coefficient on the results of the SP-C test can be neglected.

This paper studies the effective thermal conductivity of multiphase composite in which a thermal boundary resistance exists at constituent interfaces. Based on the theoretical framework of conductivity for binary system composites in the presence of a thermal contact resistance between matrix and inclusion given by Y. Benveniste and T. Miloh (1986), the fundamental concept is generalized for the case of multiphase composites with imperfect contact which permits a temperature discontinuity between matrix and inclusions of different phases. A micromechanics model, the “generalized self-consistent scheme (GSCS)” based on a particle-matrix embedding in the effective medium, is generalized to evaluate the effective conductivity of multiphase medium with imperfect thermal contact at constituent interfaces. Numerical results are given for three-phase particulate composites with spherical particles to illustrate the effect of imperfect interfaces on the effective thermal conductivity of multiphase composites.

The dynamic compressive behavior of Al2O3 (10% vol.) / TiB2 ceramic composite had been tested by using a split Hopkinson pressure bar in this paper. The results show that the main failure modes of the ceramic composite include crushed failure and split fracture along the loading direction. The former is the typical compressive failure of brittle materials. The later is tensile failure along the flaws produced during the composite manufacturing. The numerical simulation was also used to study the effect of the diameter/length ratio of the samples on the experimental results. The effect of the deformation in the bars’ ends, which contacted with the samples, was also studied in the numerical models.

In this paper, the effect of imperfect inner interface on the stress fields in the coated inclusion composite is investigated, the spring-layer of vanishing thickness model is introduced to simulate the imperfect interface, assuming that across the interface between the inclusion and the coating the interfacial traction is continuous while displacement discontinuities are permitted through interfacial traction-displacement jump relations. Numerical examples corresponding to the composites containing single coated spherical and fibrous inclusion, respectively, under shear loading at infinity, are calculated, which indicate that the imperfect inner interfaces have significant effect on stress fields of the composites.

The Small Punch Creep Tests (SP-C tests) are simulated by a Finite Element Method (FEM). The objective of the present study is to establish a foundation for the SP-C test method by investigating the deformation and stress state of the SP-C test specimen. The emphasis is placed on the dependence relation of the creep strain and the stress on the measurable quantities, such as applied loads and the central deflections. Simulation works are conducted for two different materials, one is the tungsten-alloyed 9% Cr ferritic steel and the other is 12Cr1MoV steel. The numerical results for the central deflection versus time curves are quantitatively similar to the experimental results obtained on tungsten-alloyed 9% Cr ferritic steels. From the numerical results, the relationship between the central deflection and the equivalent creep strain is approximately independent of load, temperature, and material properties. The magnitude of the equivalent stress in the central region of the SP-C specimen shows no significant change with respect to time at the secondary creep stage, an approximate equation is proposed for the assessment of the equivalent stress in the SP-C specimen. As a farther result, the high temperature creep properties of the 12Cr1MoV steel and tungsten-alloyed 9% Cr ferritic steel are appraised by numerical simulation. The results are in good agreement with the results from the standard test method. The results indicate that the small punch test technique is an effective method for the evaluation of the high-temperature creep properties of materials.

In the paper, propagation of two-dimensional viscous-plastic waves in graded layer media is investigated by numerical method. Firstly, an infinite model is used to analysis wave’s propagation in FGMs, this model has a finite gradient layer and non-reflecting boundary condition is used to simplify the model to be finite. Then the characteristic of viscous-plastic wave’s propagation in graded media is investigated on the base of this model. The following contents is researched by this model: (1) The refracted effect of functionally gradient layers on incident wave; (2) the effect of incident angle on the bottom layer’s stress ; (3) the effect of gradient layer’s thickness on the bottom layer’s stress. Finally, some interesting, reasonable and important results are obtained by our researching work.

The reflected coefficient of functionally graded layer to waves is very important as the design of impact-resistant FGMs. In the paper, the Optimization problem of propagation characteristic of elastic wave in FGM has been investigated. The relation between the top layer’s stress and displacement and the bottom layer’s is deduced from elastic propagation equation as the incident wave is a plane and harmonic elastic stress wave, then the reflected coefficient of gradient layer is obtained, and the reflected coefficient is selected as object function of optimization. The thickness of each layer is selected as optimization design parameter. The conjugate gradient method is used to get the optimal results about gradient layers’ thickness.

In the paper, firstly self-consistent model (SCM) is used for establishing the predicted formula which can predict the effective permittivity of the composite materials with core-shell type inclusions. Then the factors on the effective permittivity of this kind of composite are investigated on the base of this predicted formula. The researching results indicate the effective permittivity of composite depends on not only the volume fraction of inclusions, but also the permittivity of matrix and inclusions (core and shell). According to our works, the optimal design of composite with core-shell type inclusion must be done if we want to make this composite get better effect of absorbing wave.

In 2003, a joint research project entitled “Nano and graded thermoelectric materials/Photovoltaic-thermoelectric-wind power generation” is established in cooperation among research institutes from Japan and China. The major research institutes include State Key Laboratory of Advanced Technology for Materials Synthesis and Processing (Wuhan University of Technology, China), Shanghai Institute of Ceramics (Chinese Academy of Sciences, China), State Key Laboratory of New Ceramics and Fine Processing (Tsinghua University, China), Japan Aerospace Exploration Agency (JAXA, Japan) and Foundation for Promotion of Japanese Aerospace Technology (JAST, Japan). The main aim of this project is to develop a photovoltaic-thermoelectric-wind power generation system with high efficiency solar energy conversion. The key works of the project include: (1) fabrication of high efficiency nano thermoelectric materials with a maximum figure of merit Z≥1.3; (2) design and fabrication of nano graded thermoelectric material/component with efficiency conversion larger than 12% for wide temperature range and (3) design and construction of photovoltaic- thermoelectric coupled power generation system. The recent progress about the joint research project is reported in this paper. Emphasis is put on the mechanism, design and fabrication of high efficiency nano graded thermoelectric materials. The future research plan is also mentioned in brief.

The numerical simulation for the Small Punch creep (SP-C) tests is conducted using a Finite Element method. The objective of the present study is to obtain the deformation states of the SP-C specimen and to estimate the feasibility of SP-C test method for high-temperature creep properties. The emphasis is put on the relationship between the equivalent creep strain and the central deflection of the SP-C specimen. The time history of central deflection and equivalent creep strain is obtained by finite element method and the effects of the load, temperature and material properties on the relationship of central deflection and equivalent creep strain are discussed. From the numerical results, the relationship between the central deflection and the equivalent creep strain is approximately independent of load, temperature, and material properties. As a farther result, the high temperature creep properties of the 12Cr1MoV steel are appraised by numerical simulation. The results are in good agreement with the results from the standard test method. The results indicate that the small punch test technique is an effective method for the evaluation of the high-temperature creep properties of materials.

This paper studies the optimization problem of composition distribution of functionally graded material (FGM) coating subjected to steady heat flux loading. The investigation object of the paper is an infinite plate substrate with FGM coating in the surface. The materials are heated at the ceramic surface (upside) with a steady high-intensity heat flux input, and cooled at the metal surface (underside) with flowing liquid nitrogen. The thermal stress distribution and the temperature distribution are obtained by formulation. For optimization, the design variables are the thickness of each interlayer and the volume fraction distribution of the coating. The objective function is the danger coefficient and the restricted condition is the total thickness of FGM plate and heat insulation coefficient. In the paper, three different optimization schemes are considered and compared. The µGA and related parameters are discussed in detail. Optimizing the thermal stress distribution and minimizing the danger coefficient are carried out by µGA. The optimization results of composition distribution are gained, and the results show the optimum composition distribution can distinctly reduce the danger coefficient.

The present paper investigates the creep phenomenon of the functionally graded materials under high temperature environment by the computational micromechanical method (CMM). Based on the real microstructure of the functionally graded interlayer with different component volume fractions, the emulation experiment is implemented for the creep test numerically and the creep parameters are obtained. A further series of simulation works are carried out to investigate the creep phenomenon of FGM interlayers in more detail. Numerical results show that the creep phenomenon is obvious not only for the metal-rich interlayers but also for the ceramic-rich interlayers. The creep property of ceramic/metal interlayer depends on the material’s properties of the ceramic obviously. It is remarkable that the creep strain rate of the ceramic/metal interlayer is larger than the corresponding one of pure metal under the same load when the modulus of the ceramic component is lower than the one of the metal component.

By using cryogenic treatment on 7A04 aluminum alloy tested with micrographic analysis and mechanical properties test, we studied the impact on mechanical properties of 7A04 aluminum alloy The results showed that the strength of 7A04 aluminum alloy could be highly increased and the grain size would be reduced in the process through being treated in 480°C/80min + aging in 120°C/4h + cryogenic treatment + aging at 120°C/16h.7A04 aluminum alloy are more fully recrystallized to grain refinement and the tensile strength of it can be increased to 720Mpa after the treatment.

The coupling/interaction between the thermal damage and heat conduction of ceramic-metal FGMs under thermal shock and cyclic thermal loading is an important phenomenon. A theoretical model on the coupling phenomenon is developed to examine, quantitatively, the relationship between the thermal shock damage and effective thermal conductivity. The model is investigated with an effective medium method characterized by a self-consistent micromechanics. The thermal damage is treated as randomly distributed, penny-shaped microcracks. The damage effect is accounted for by introducing a crack density parameter. The effective thermal conductivity of the FGM interlayers is derived in terms of the model and connected with the crack density parameter. The model is verified by a concrete example and provides a new, useful method for the thermal damage evaluation of the materials.

A random microstructure finite element method for effective properties of functionally graded materials is developed. The method combines a random mathematical model and a computer automatically geometry formation technique with finite element analysis The random microstructure either in a dispersive form or in an interwoven form can exactly be described. The interaction of the inclusion-inclusion and of the inclusion-matrix as well as the influence of boundary conditions in the microstructure can accurately be treated The method is verified by two examples and proved to be very effective in predicting macro properties of the materials, especially when the microstructure contains randomly distributed cracks.

The analysis model for the response of ceramic-metal FGMs under dynamic thermal loading is investigated. Emphasis is put on the effects of the residual stress, thermal- mechanical coupling and hardening model for the materials. It is shown that the three effects are significant when the materials’ response is inelastic and should carefully be considered in constructing the analysis model.

The processing-working unified analysis model and optimum design of ceramic-metal functionally graded materials are studied. Emphasis is placed on the effect of the residual stress on the working stress and optimum design of the materials. Two analysis models for the residual stress effect are examined: one is a separate analysis model and the other is an unified analysis model. It is indicated that the effect of the residual stress is significant and the optimum design of the FGMs should be based on the processing-working unified analysis model when the materials response is inelastic.

A numerical study is presented that simulates small punch creep (SP-C) tests using a finite-element method (FEM). The objective of the present study is to develop a miniaturized testing methodology for high-temperature creep properties. The numerical simulations have been shown to produce deflection versus time curves that are quantitatively similar to the experimental results obtained on tungsten-alloyed 9 % Cr ferritic steels. It is also demonstrated that the numerically predicted curves show the steady state (secondary) creep stage. Furthermore, the numerical simulations reveal that the magnitude of the equivalent stress in the central region of the SP-C specimen shows no significant change with respect to time at the secondary creep stage, supporting the use of the present SP-C testing method to characterize the secondary creep deformation rate. Finally, an approximate equation is proposed for the assessment of the equivalent stress in the SP-C specimen in terms of the load and testing parameters.