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A VIEWPOINT OF THE TENSORAL PROPERTY OF COORDINATE TRANSFORMATION COEFFICIENT AND ANALYSISON THE CONCEPT OF HYBRID TENSOR1)
YIN Yajun
Mechanics in Engineering    2019, 41 (1): 1-9.   DOI: 10.6052/1000-0879-18-154
Abstract618)   HTML4)    PDF(pc) (2778KB)(185)       Save

This paper discusses a basic problem: Is the coordinate transformation coefficient the component of a tensor? The conventional viewpoint is that the coordinate transformation coefficient is not the component of a tensor. To reveal the essence of the coordinate transformation coefficient, the basic concept of the tensor is revisited. A new concept, i.e. the hybrid tensor, is defined. On the basis of the new concept, the conventional viewpoint is negated: the coordinate transformation coefficient is indeed the component of a tensor. That is to say, it is the hybrid component of a metric tensor. Thus, the concept of tensors is extented.

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REVIEW ON OPTIMIZATION OF ASTEROID CAPTURE ORBITS
BAOYIN Hexi, BAO Changchun
Mechanics in Engineering    2019, 41 (5): 511-519.   DOI: 10.6052/1000-0879-19-106
Abstract109)   HTML22)    PDF(pc) (283KB)(191)       Save

The asteroid is of great significance for studying the formation of planets, the origin of life on the Earth, the defense against the collision of asteroids to the Earth and the mining on asteroids. Due to the insufficient capacity of the existing propulsion technology, the velocity increment needed to optimize the asteroid capture is the key for a successful capture mission. This paper reviews the capture orbit optimization method for asteroid and the extended capture period with the impulse thrust and lowthrust propulsions, including the strategy to capture asteroids by the gravity assisted and resonant orbital techniques, the continuous low thrust and temporary asteroid capture, and the scheme of extending the capture period.

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APPLICATIONS AND CHALLENGES OF STRUCTURAL OPTIMIZATION IN HIGH-SPEED AEROCRAFT 1)
QUAN Dongliang, SHI Guanghui, GUAN Chengqi, WANG Jian, LUO Junhang, SONG Feng, WANG Bo, GAO Tong, ZHU Jihong, ZHANG Weihong
Mechanics in Engineering    2019, 41 (4): 373-381.   DOI: 10.6052/1000-0879-18-448
Abstract269)   HTML16)    PDF(pc) (2880KB)(247)       Save

With its great national strategic importance and socio-economic benefits, the high-speed vehicle always plays a specific role in the field of aerospace. In this paper, the structural optimization technique and its application in the aircraft design are reviewed firstly. Then, the specific applications of structural optimization techniques in the high-speed vehicle design are then discussed in the context of the typical service environment and the design requirement. We show typical cases subsequently with applications in the concept design of the high-speed vehicle and in the innovative and improved design of their parts over the last years. In view of the solid theoretical foundations as well as the numerous successful engineering practices of the structural optimization, it not only provides an effective tool, but also brings about revolutionary changes for the design of high-speed vehicle structures. It is anticipated that the structural optimization supplemented by the empirical design will surely be a standard procedure for the aircraft design, and the practice-oriented research will undoubtedly enhance the core competitiveness of the aerospace industry in China

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THE COVARAINT DERIVATIVES OF NATURAL BASE VECTORS AND THE ADVANCES IN GENERALIZED COVARAIBILITIES1)
Yajun YIN
Mechanics in Engineering    2019, 41 (3): 255-264.   DOI: 10.6052/1000-0879-18-226
Abstract421)   HTML34)    PDF(pc) (2779KB)(318)       Save

This is the question asked in class: is it possible to obtain the covariant derivative of natural base vectors? To answer this question, the idea of axiomazitaion is introduced, the concepts of the generalized component and the generalized covariant derivative are defined. Based on these new concepts, the classical covariance is developed into the generalized covariance, and the classical covariant differentiation is developed into the generalized covariant differentiation. This paper summarizes the main difficulties and the important points of the above explorations, and shows the abstractions of the generalized covariant derivatives and the advances of the generalized covaraibilities.

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RESEARCH PROGRESS OF LOCKED-IN STRESS IN ROCKS1)
GENG Hansheng, XU Hongfa, CHEN Xiao, BAI Zhun
Mechanics in Engineering    2018, 40 (6): 613-624.   DOI: 10.6052/1000-0879-18-195
Abstract325)      PDF(pc) (1949KB)(483)       Save

The influence of the locked-in stress on the rock mechanical properties cannot be ignored. Since Chen Zongji proposed the definition of the locked-in stress in rocks, there were very few related studies. Starting from the definition, combined with the current development of the rock mechanics, this paper expands the concept of the locked-in stress,in a new definition of the locked-in stress in rocks. The forms of the stress in accordance with the new definition of the locked-in stress in the rock mechanics research are classified. The variation law of various kinds of locked-in stress and its empirical formula are summarized. The correlation between the locked-in stress and the excavation of the underground engineering and its influence are discussed. This paper provides a new way to explain the special phenomenon of deep rock mechanics.

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PROGRESS IN STUDIES OF FLEXIBLE STRESS SENSITIVE CONDUCTIVE POLYMER COMPOSITES1)
LIU Hu, LIU Yongzhi, DAI Kun, GUO Zhanhu, LIU Chuntai
Mechanics in Engineering    2018, 40 (5): 481-494.   DOI: 10.6052/1000-0879-18-250
Abstract213)   HTML11)    PDF(pc) (47164KB)(248)       Save

The flexible stress sensitive conductive polymer composites (CPCs) have a wide application prospect in the fields of the wearable human machine interaction, the medical monitoring, the portable sports equipment and the bionic robot, and others. The conductive percolation theory, the response mechanisms and the sensitivity of the stress sensitive CPCs are discussed in this paper. The response characteristics of different types of stress sensitive CPCs are reviewed, including the numerical predications. Finally, the future development is commented.

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INTERFERENCE OF SHOCK AND BOUNDARY LAYER IN SUPERSONIC FLOW
LIU Peiqing, GUO Zhifei
Mechanics in Engineering    2018, 40 (4): 357-361.   DOI: 10.6052/1000-0879-17-363
Abstract329)   HTML12)    PDF(pc) (12452KB)(364)       Save

The compression boundary layer transition and separation caused by the interference of the shock and the boundary layer directly affect the drag, surface thermal protection and the flight performance of flying vehicles. This paper first reviews the past work on the interference between the shock wave and the boundary layer. And then, the effects of the forward shock, the oblique shock and the head shock on the laminar flow and the turbulent boundary layer of supersonic and transonic flows are studied and compared. The shock waves of different intensities have different effects on the boundary layer.A strong interference is more likely to cause the separation and the airfoil stall.

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SOME FUNDAMENTAL CONCEPTS AND RESEARCH METHOD OF STRUCTURAL TOPOLOGY OPTIMIZATION
ZHOU Kemin
Mechanics in Engineering    2018, 40 (3): 245-252.   DOI: 10.6052/1000-0879-18-054
Abstract377)   HTML17)    PDF(pc) (1757KB)(422)       Save

Some fundamental concepts and problems in the research field of the structural topology optimization are introduced briefly. The essential characteristics of the truss-like and its discretization are analyzed. The classical analytical solutions as the benchmarks are listed in the references. The optimization strategies and the characteristics of various numerical methods for the structural topology optimization are reviewed. The numerical instabilities, such as the mesh-dependencies, the singular optima, the checkerboards and the local constraints, commonly in the structural topology optimization, are explained. The fundamental principles of the optimality criteria, the sequential programming and the heuristic methods are discussed.

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DRAG REDUCTION TECHNIQUE FOR LARGE TRANSPORT AIRCRAFT
LIU Peiqing, ZHANG Wen, GUO Hao
Mechanics in Engineering    2018, 40 (2): 129-139.   DOI: 10.6052/1000-0879-17-295
Abstract222)   HTML4)    PDF(pc) (19858KB)(431)       Save

The techniques for the drag reduction of large transport aircraft are reviewed in this paper. The techniques intended to reduce the friction drag, the induced drag and the wave drag are reviewed specifically. Techniques like the suction control for delay boundary layer transition, the riblets for reducing turbulent friction drag, and the winglet are relatively mature for practical application. Distributed roughness, plasma actuators and the contour bump are most like to be used in the newly designed large transport aircraft. These newly developed techniques might be useful in further improving the drag characteristic of the next generation aircraft.

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ADVANCE OF EXPERIMENTAL TECHNOLOGIES FOR STRUCTURAL MODAL TEST IN HIGH TEMPERATURE ENVIRONMENTS
YU Kaiping, BAI Yunhe, ZHAO Rui, ZHOU Haotian
Mechanics in Engineering    2018, 40 (1): 1-12.   DOI: 10.6052/1000-0879-17-288
Abstract271)   HTML6)    PDF(pc) (28136KB)(1678)       Save

Since the hypersonic vehicle is acted by a serious aerodynamic thermal load caused by the flight through the atmosphere, it is necessary to consider the effect of the high temperature in the ground test of the vehicle structures. But the structural modal experiment in a high temperature environment is far more complex than the normal modal experiment with many technical difficulties to be solved. In this paper, the advance of the thermal modal test technology is reviewed. The characteristics and the applicability of the excitation and measurement techniques to be used in the high temperature environment are discussed in detail. The development direction and the research focus of the structural modal test technology in the high temperature environment are suggested.

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RESEARCH ADVANCES IN THE TREFFTZ FINITE ELEMENT METHOD
WANG Keyong, LI Peichao
Mechanics in Engineering    2017, 39 (5): 433-440.   DOI: 10.6052/1000-0879-17-115
Abstract397)      PDF(pc) (3696KB)(1053)       Save

The Trefftz finite element method (TFEM) is an efficient numerical approach with many joint advantages of the conventinal finite and boundary element methods. Based on the mutual independent interpolation modes, the finite element formulation involving the boundary integrations only is derived by incorporating the hybrid functional and the Gaussian divergence theorem. The research advances in the internal interpolation function, the treatment of the source term, the special-purpose element and the nonisotropic material during the past decade (2007-2016) are reviewed and several directions are pointed out for the future development.

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SURVEY OF ASTRODYNAMICS SOFTWARE DEVELOPMENT
LUO Yazhong, SUN Zhenjiang, QIAO Dong
Mechanics in Engineering    2017, 39 (6): 549-560.   DOI: 10.6052/1000-0879-17-248
Abstract1054)      PDF(pc) (305KB)(3498)       Save

The astrodynamics software is a bridge between the astrodynamics theory and the engineering application, which can evidently improve the e-ciency and the ability of the space mission design and analysis. There are many mature software systems in the world, but many of them are not available in our country. In recent years, great progress has been made in the fleld of the national astrodynamics research and the engineering applications, but the mature astrodynamics software remains almost a blank area. The development of the international astrodynamics software is surveyed and sorted into two kinds:the space mission analysis and the spacecraft trajectory optimization. The representative open-source and commercial software systems are introduced, including JAT, STK, Freeflyer, POST and ASTOS. Additionally, the development of the Chinese astrodynamics software is also reviewed. At last, the technical characteristics of difierent astrodynamics softwares are summarized, and preliminary suggestions for the development of a mature astrodynamics software in China are given.

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GEOMETRIZATION OF MECHAINICS
WU Jike
Mechanics in Engineering    2017, 39 (4): 323-332.   DOI: 10.6052/1000-0879-17-181
Abstract987)      PDF(pc) (9849KB)(2454)       Save

In the development of mechanics, the geometrization of theoretical systems of mechanics, is introduced. Dynaminc systems of mechanics reduced to Riemann geometry and Symplectic geometry are presented, the concepts of duel space, symmetry, transform, invariant, and there general applications in mechanics are introducd.

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Recent progress of satellite micro-vibration control based on the parallel platform
YU Kaiping, JIAO Jian, WU Ying
Mechanics in Engineering    2017, 39 (3): 219-225,259.   DOI: 10.6052/1000-0879-17-072
Abstract317)      PDF(pc) (10318KB)(496)       Save

The high-resolution capability is an important development direction for satellite in our country. In this respect, a key technique is the satellite micro-vibration control. This paper reviews the developments of the parallel platform for solving the problem of micro-vibration control in China and abroad, with a comparison of the platform manufacture and the performance conditions. It is shown that the level of the micro-vibration control technology based on the parallel platform in China is still some way behind those of other advanced countries. This paper reviews the typical configuration design, the dynamics modeling, the control system design, the platform optimization and the ground test of the parallel platform. The further research directions for the micro-vibration control technology in our country are suggested.

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THERMAL VIBRATION OF TYPICAL NANO-STRUCTURE
LIU Rumeng, WANG Lifeng
Mechanics in Engineering    2017, 39 (2): 109-119.   DOI: 10.6052/1000-0879-16-429
Abstract554)      PDF(pc) (13573KB)(862)       Save

The thermal vibration is the inherent vibration of nanostructures, which plays an important role in the dynamics of nanostructures. The quantum effects, the boundary effects and the van der Waals interaction have a significant influence on the thermal vibration of nanostructures. The carbon nanotubes and the graphene were extensively studied for their novel electronic properties and superior mechanical strength. This paper reviews some research methods for the thermal vibration of nanostructures, the thermal vibration of the carbon nanotube and the graphene in low temperatures and the nonlinear thermal vibration of the carbon nanotube.

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TRANSFER ORBIT DEVIATION PROPAGATION ANALYSIS AND MID-COURSE CORRECTION FOR HUMAN LUNAR MISSION
LI Haiyang, HE Boyong, CAO Pengfei
Mechanics in Engineering    2017, 39 (1): 1-6.   DOI: 10.6052/1000-0879-16-291
Abstract549)      PDF(pc) (1477KB)(569)       Save

The transfer orbit for the human lunar mission means that between the trans-lunar orbit and the trans-earth orbit, and it has the characteristics of long flight time, complex dynamics model, and strong nonlinear and variable coe-cients. The controllability of the inevitable deviation afiects the result of the task execution, even the success or the failure of the engineering task directly. This paper reviews the studies of the transfer orbit of human lunar mission, the analysis method of the deviation propagation, the mid-course correction optimal strategy and the mid-course correction aiming algorithm. At last, some suggestions are made or the mid-course correction of the Chinese human lunar mission in the future.

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UNIQUE DYNAMICS OF ASTEROIDS
LI Junfeng, ZENG Xiangyuan, ZHANG Yun
Mechanics in Engineering    2016, 38 (6): 603-611.   DOI: 10.6052/1000-0879-16-354
Abstract1284)      PDF(pc) (14126KB)(849)       Save

Millions of asteroids are in various shapes, which show unique dynamical phenomena, including their own revolutions and the vicinal surrounding objects. This paper reviews the recent development of studies of asteroids. Significant effects on the long-term evolution of asteroids' attitude and orbit are introduced, i.e., the Yarkovsky effect and the YORP effect. Modeling methods of their irregular gravitational fields are presented as well as naturally periodic orbits in complex universal curves. Some basic problems and potential research directions are suggested.

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Cited: Baidu(1)
ANALYSIS OF THE ENERGY ABSORPTION PROPERTIES FOR TUBULAR STRUCTURE UNDER AXIAL COMPRESSION OF DIFFERENT FAILURE MODELS
QIU Xinming, PAN Mingle, YU Xiaohuan, WANG Wei, LIU Yuzhe
Mechanics in Engineering    2016, 38 (5): 477-492.   DOI: 10.6052/1000-0879-16-243
Abstract585)      PDF(pc) (12678KB)(631)       Save

Tubular structures such as circular tubes and square tubes under axial compression, are widely used as structural components in engineering applications. Considering the difference of tube geometries, boundary conditions and material properties, we classify the failure of tubes under axial compression into 5 different mechanisms: progressive buckling, global buckling, inversion, expansion and splitting. In this paper, the theoretical, experimental and numerical studies about the different failure modes of tubes under axial compression are reviewed, and the mechanical responses and energy absorption properties are compared and discussed.

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PROGRESS IN STUDIES ON DISCRETE BOLTZMANN MODELING OF PHASE SEPARATION PROCESS
XU Aiguo, ZHANG Guangcai, GAN Yanbiao
Mechanics in Engineering    2016, 38 (4): 361-374.   DOI: 10.6052/1000-0879-16-006
Abstract485)      PDF(pc) (33914KB)(423)       Save

The studies on discrete Boltzmann modeling and simulation of phase separation are reviewed. According to the system component, the studies cover the single-component two-phase separation and the multi-component phase separation. According to the physical modeling, the studies cover the LBM (lattice Boltzmann method) simulations based on traditional hydrodynamic modeling and discrete kinetic modeling of the phase separation system. According to the main focus, the topic covers method/model studies and physical behavior investigations. The discrete kinetic modeling has brought some deeper insights into the phase separation process. The features of non-equilibriums obtained from discrete Boltzmann simulations can serve as some simple and effective physical criteria for dividing the two stages of phase separation, and can be used to discriminate and track various interfaces.

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Cited: Baidu(14)
RESEARCH PROGRESS OF LIQUID SLOSHING IN MICROGRAVITY
MIAO Nan, WANG Tianshu, LI Junfeng
Mechanics in Engineering    2016, 38 (3): 229-236.   DOI: 10.6052/1000-0879-15-185
Abstract442)      PDF(pc) (1379KB)(516)       Save

Sloshing of liquid propellant in microgravity and its influence on the attitude control system have been studied for several decades. Accurate modeling is necessary, especially, for modern spacecrafts carrying large amounts of liquid propellant. Research progress on this issue is reviewed, including a summary of analytical methods for both linear and nonlinear sloshing, an introduction of numerical techniques such as modal analysis and CFD (computational fluid dynamics) methods, and also a description of experimental approaches and advances. Finally, some critical problems concerning liquid sloshing in microgravity are proposed and discussed.

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Cited: Baidu(3)
DYNAMICS OF ENGINEERING CABLE:NONLINEAR MODELLING AND ANALYSIS
GUO Tieding, KANG Houjun, WANG Lianhua, ZHAO Yueyu
Mechanics in Engineering    2016, 38 (2): 119-125.   DOI: 10.6052/1000-0879-15-184
Abstract805)      PDF(pc) (561KB)(745)       Save

Cables are widely used as tension structure members in engineering as they are light, flexible and of high strength. On one hand, the external excitations induce cable's complex dynamic responses with large amplitudes, which might cause structure's failure. On the other hand, the cable structure is a typical nonlinear system with both quadratic and cubic nonlinearities, which means extensive nonlinear dynamic behaviors. Therefore, the cable dynamics is an interesting research issue in both engineering and applied mechanics, and our knowledge about the cable dynamics is much enriched in the past few decades. This paper reviews the progress of cable dynamics, including cable's dynamic models, internally resonant dynamics, moving support induced cable dynamics, and complex excitation induced cable dynamics. And we also discuss the limitations of the present cable dynamics.

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A REVIEW OF NUMERICAL SIMULATIONS OF HYDRO-FRACKING IN SHALE GAS RESERVOIR
JIN Yan, CHENG Wan, CHEN Mian
Mechanics in Engineering    2016, 38 (1): 1-9.   DOI: 10.6052/1000-0879-15-225
Abstract682)      PDF(pc) (9736KB)(1117)       Save

In the numerical simulation of hydraulic fracturing in a shale gas reservoir, both the shale rock's properties and the multistage hydro-fracking technique of the horizontal well should be considered, which is a difficult problem of mechanics. In this paper, the mechanical characteristics of the shale rock and the multistage fracking technology of the horizontal well in the shale gas reservoir are discussed, as well as the applications of the extended finite element method, the boundary element method and the discrete element method in hydraulic fracturing and their advantages and limitations. It is indicated that the three dimensional displacement discontinuity method of the boundary element method is an effective approach to model the propagation of multistage fractures.

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Cited: Baidu(1)
REVIEW OF TRAJECTORY DESIGN FOR MANNED LUNAR MISSION
BAOYIN Hexi, LI Jingyang
Mechanics in Engineering    2015, 37 (6): 665-673.   DOI: 10.6052/1000-0879-15-139
Abstract489)      PDF(pc) (1346KB)(650)       Save

At the beginning of this century, the lunar exploration programs Constellation, Aurora and Chang'e are proposed by NASA(National Aeronautics and Space Administration), ESA(European Space Agency) and CAST(China Academy of Space Technology), respectively. They open a new page for human being returning to space, and pose new requirements for the manned lunar mission. These requirements include more diversified detection scope, more accurate trajectory design and more strict safety measures for human crew. These make the program more complicated and sophisticated. This paper reviews in detail the developments of manned lunar mission's trajectory, Earth——Moon transfer trajectory, autonomous rendezvous guidance and lunar global coverage design, and presents the relevant hot topics in these fields. Finally, this paper outlines the tendency of future researches on this direction.

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Cited: Baidu(2)
RESEARCH PROGRESS OF UNSATURATED SOIL MECHANICS
LIU Yan, ZHAO Chenggang, CAI Guoqing, LI Jian
Mechanics in Engineering    2015, 37 (4): 457-465.   DOI: 10.6052/1000-0879-15-008
Abstract626)      PDF(pc) (745KB)(681)       Save

This paper firstly reviews the studies of the effective stress of unsaturated soils and points out that two stress variables are preferred to be chosen to establish a constitutive model at present. The paper also explains the definition of the matric suction, which involves the effects of the capillary component and the adsorptive component. Secondly the paper discusses the strength of unsaturated soils. The shear strength is usually formulated by the extended Mohr-Coulomb Criterion. The tensile strength also affects the soil behavior due to the capillary effect and thus cannot be ignored. Thirdly, the paper reviews the studies of the constitutive models for unsaturated soils, including the models based on the net stress and the matric suction and that based on the Bishop effective stress and the matric suction. The double pore structure model is also discussed. Finally, the paper addresses the applications of the thermodynamic method and the porous media theory in unsaturated soils. It is shown that these two methods-using the thermodynamic principles to establish the constitutive framework, and using the porous media theory to study the complicated coupling effect of unsaturated soils are subjects very worthy to be developed.

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Cited: Baidu(5)
EXPANSION POWER OF COMPRESSED MICRO FLUID INCLUSIONS AS THE CAUSE OF ROCKBURST
YUE Zhongqi
Mechanics in Engineering    2015, 37 (3): 287-294.   DOI: 10.6052/1000-0879-15-089
Abstract648)      PDF(pc) (10999KB)(619)       Save

The rockburst (rock burst) is a peculiar, abnormal, localized, isolated, delayed, sudden and damaging phenomenon associated with the underground rock excavation. Several hours after the completion of the excavation, some parts of the in-situ intact rock wall might be actively, suddenly and vigorously ejected, thrown and blown off from the original wall into the excavated open space, with high initial ejecting velocity and kinetic energy. It often causes fatality, injury and damage because its occurrence is usually unforeseeable and unpredictable. The rockburst is still a worldwide tough problem that puzzles the international communities of rock mechanics in spite of tremendous research efforts over the past 50 years. This paper puts forward a hypothesis of micro-fluid inclusions as the cause and mechanism of the rockburst. The fluid inclusions in the micro-voids of intact rocks may have a high initial pressure equaling to the average of the three in-situ principal stresses. The fluid inclusions with a high initial pressure can have a high expansion power. They can flow, migrate and turn from the liquid phase into the gas phase after the rock excavation. Their physical and chemical expansion power can cause the rockburst of the excavated intact rock wall. This hypothesis offers effective solutions for the rockburst problem to reduce and eliminate its damage.

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Cited: Baidu(3)
PROGRESS IN MEASUREMENT TECHNOLOGY FOR DRILL STRING VIBRATION
DI Qinfeng, PING Junchao, LI Ning, WANG Wenchang, WANG Mingjie, ZHANG He
Mechanics in Engineering    2015, 37 (5): 565-579.   DOI: 10.6052/1000-0879-15-044
Abstract550)      PDF(pc) (18839KB)(922)       Save

The drill string fatigue failure caused by drill string vibration is increasingly an issue related with the development of ultra-deep drilling operations. The research methods of drill string vibration can be classified into two types, the theoretical analysis or numerical simulation, and the the measurement technology. Owing to various complicated nonlinear mechanical problems, especially, the impact between moving drilling tools and hole wall, it is dificult to study the drill string vibration in many cases using the theoretical analysis or numerical simulation method, and therefore, the down hole vibration measurement technology becomes more and more important. This paper gives a comprehensive and systematic review of the status and progress of drill string vibration measurement technology, followed by a detailed discussion of the working mechanism, analytical approach and application technology for several overseas measurement tools which have been widely used around the world. The results would provide important supports to develop the down hole vibration measurement technology in our country.

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Cited: Baidu(1)
RECENT ADVANCES AND REVIEW OF BRIDGE SAFETY MONITORING
MA Hongwei, NIE Zhenhua
Mechanics in Engineering    2015, 37 (2): 161-170,181.   DOI: 10.6052/1000-0879-14-106
Abstract830)      PDF(pc) (1035KB)(969)       Save

The development of damage detection methods and safety monitoring technology of bridge are analyzed and summarized, and the existing methods are classified. The five major challenges and problems of the current existing methods in the application and research are also analyzed. Some hot research issuesdeveloped recently are further discussed. Then, some suggestions and the direction of the next research work are put forward, and the idea that using big data method to deal with bridge safety monitoring is also put forward, hoping that these ideas can inspire the researchers in the future research work.

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Cited: Baidu(3)
ADVANCES IN STUDIES OF THE MECHANICAL PERFORMANCE OF CELLULAR METALS AND RELATED SANDWICH STRUCTURES
JING Lin, WANG Zhihua, ZHAO Longmao
Mechanics in Engineering    2015, 37 (1): 1-24,48.   DOI: 10.6052/1000-0879-14-180
Abstract1123)      PDF(pc) (4725KB)(1818)       Save

The high-porosity cellular metals and the related sandwich structures are a new type of light-weight structural and functional material/structure. They are attractive for their high specific strength, high specific stiffness and excellent energy absorption capability. This paper reviews various processing techniques, the mechanical performance and the application fields of the sandwich structures with cellular metal cores. The mechanical behavior of metallic sandwich structures, including beams, plates and shells, subjected to quasistatic and dynamic loads is discussed, including theoretical predictions, numerical simulations and experimental results. The discussion also includes the deformation/failure, the dynamic response and the energy absorption of sandwich structures.

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Cited: Baidu(9)
PROGRESS IN MECHANICS OF THE COCHLEA
MA Fuyin, WU Jiuhui
Mechanics in Engineering    2014, 36 (6): 685-715.   DOI: 10.6052/1000-0879-13-477
Abstract600)      PDF(pc) (8023KB)(1521)       Save

The mechanics of cochlea is the core of hearing sciences and physiological acoustics, as well as a representative biomechanics topic. The study of cochlear mechanical properties could promote the related studies of psychoacoustics. This paper reviews the mechanics of the cochlea in two parts, the macro and micro mechanics, focusing on the development trend of the cochlear mechanics and application prospects. It is suggested that the cochlea is a part of the inner ear and its mechanical response provides us with many aspects of our amazing sensitive and selective hearing, with an accurate frequency response from 20~20 000 Hz and with the stimulus signal being able to be amplified more than 4 000 times.

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Cited: Baidu(2)
THE RESEARCH PROGRESS OF LATTICE BOLTZMANN METHOD IN NON-NEWTONIAN FLUID FLOW
LI Yong, LIU Wenqin
Mechanics in Engineering    2014, 36 (4): 383-395.   DOI: 10.6052/1000-0879-14-168
Abstract950)      PDF(pc) (3014KB)(1240)       Save

LBM (lattice Boltzmann method) allows straightforward calculations of the local shear rate to the second-order accuracy, so it has some advantages in the simulation of the non-Newtonian behavior of flows. Although the suitability of LBM for the non-Newtonian flow has been well demonstrated, the algorithms are mainly through instantaneously regulating the local relaxation time in the BGK (Bhatnagar-Gross-Krook) approximated collision term to match its corresponding viscosity for reflecting the effect of the local rheology variation.This approach, however, might cause some numerical instabilities when the relation time is close to 1/2.In this paper, the advances of LBM applied to generalized Newtonian flows are reviewed.The methods to mitigate numerical instabilities are described and the results are compared.Several ways of extending LBM to viscoelastic flows in the literature are introduced.Finally the prospective developments of LBM for non-Newtonian flows are suggested.

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