力学进展

MULTI-SCALE MODELING AND DAMAGE ANALYSES OF LARGE CIVIL STRUCTURE ------MULTI-SCALE MECHANICS FROM MATERIAL TO STRUCTURE

2007, 37(3): 321-336. doi: 10.6052/1000-0992-2007-3-J2007-039

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This paper discusses firstly a newchallenge in securing safe and reliable service of large civilstructures: multi-scale modeling and damage analyses. Thenthe applications, the features of spatial multi-scales involved and therelated issues for multi-scale mechanics of materials and structures arereviewed. The theories and methods ofmulti-scale mechanics and multi-scale material modeling arebriefly discussed and several methods are paid a special attention,such as asymptotic analysis of periodical heterogeneous materials, partition of unity method andmulti-scale reproducing kernel method. The engineeringbackground and the current research progress for multi-scale structuralmodeling and damage analyses of large civil structure are summarized, andseveral key issues are proposed, among which are bridging insimulation, updating and verification of the multi-scale structural model,damage evolution in multiple temporal scales, trans-scale sensitivity in thesimulation of structural deterioration and final failure, and thestrategies of multi-scale modeling and simulation in engineeringcomputation of large civil structure.

THE ESTIMATION OF RESPONSE STATISTICS IN STATISTICAL ENERGY ANALYSIS AND ITS RESEARCH PROGRESSES

2007, 37(3): 337-345. doi: 10.6052/1000-0992-2007-3-J2006-086

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Statistical energy analysis (SEA) is a powerful tool in studies on the structural-acoustic coupled vibration response of complexdynamic system, and the estimation of response statistics in SEA is abasis for evaluating the analysis accuracy, and is an important part of SEA. The basic theory of SEA and the theory of the estimation ofresponse statistics in SEA are briefly discussed and the research progressesof the estimation of response statistics in SEA are reviewed. Some problemsin the estimation of response statistics in SEA are pointed out,together with some further research topics. Particularly, the method ofvariance analysis of structure response based on Poisson natural frequencyspacing and natural frequency spacing conforming to the Gaussian orthogonalensemble in the estimation of response statistics are discussed, and itsimportance in the development of the estimation of responsestatistics in SEA is shown.

LIQUID FRAGILITY AND ITS CORRELATION WITH THE MECHANICAL PROPERTIES

2007, 37(3): 346-360. doi: 10.6052/1000-0992-2007-3-J2006-143

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The concept of liquid fragility, firstly introduced byAngell in the 1980s, has provided new insight on thenature of glassy state and built a bridge between the glass-formed liquidsand the resulting solids. The study on the glass transition based on fragilityand Mode coupling theory or potential energy landscape has become an areaof intensive research in recent years. Exploring the correlationbetween the fragility of liquids and the basic property of the correspondingglass phase should be a promising field for mechanics. In this paper,the basic phenomena and several dominant theories about the glasstransition, the development of the relationship between the fragility andthe basic property of glasses are first reviewed, and then several pointsthat deserve further investigations in this field are proposed.

A REVIEW ON CONSTITUTIVE MODELS FOR PLASTIC DEFORMATION OF METAL MATERIALS UNDER DYNAMIC LOADING

2007, 37(3): 361-374. doi: 10.6052/1000-0992-2007-3-J2006-184

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The constitutive models for plastic flow ofmetal materials under dynamic loading, such as explosive or impact loading,is very important in the impact dynamics, and its studies in recentdecades have greatly promoted the development of shock physics, impactdynamics and material sciences, among others. In this paper, some importantconstitutive models for numerical calculations of dynamic plasticdeformation of metal materials are reviewed. Their application range,advantage and disadvantage are discussed in details. A new constitutivemodel, PTW model is specially addressed.

ADVANCES IN THE TENSILE INSTABILITY OF SMOOTHED PARTICLE HYDRODYNAMICS APPLIED TO SOLID DYNAMICS

2007, 37(3): 375-388. doi: 10.6052/1000-0992-2007-3-J2006-053

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SPH (smoothed particle hydrodynamics) is a gridlessLagrangian numerical method based on kernel approximation. In this method,the continuum equations of fluid dynamics are replaced by particleequations. SPH can deal with large deformation and extensive tangling, whichare difficult to be handled in FEM, as well as free surface and materialinterface, which are tricky problems in FDM. SPH is robust in the simulation ofimpact, explosion and crack. However, the tensile instability is its biggestdrawback in the applications to solid dynamics. Von Neumannstability analysis shows that the criterion for stability or instabilitycan be expressed in terms of the stress state and the second derivative of the kernel function.At present, SPH tensile instability is alleviated in the stress point method,artificial stress method, CSPM (corrected smoothed particle hydrodynamicsmethod), conservative smoothing method and other methods, but they can not completely overcome SPH tensile instability. In thispaper, the theory of SPH and the idea of Von Neumann stability analysis areintroduced, and the research results and recent advances in SPH tensileinstability are analyzed. The existing problems and future trends inthese fields are discussed.

ADVANCES IN THE NUMERICAL INVESTIGATIONS ON WRINKLES IN SPACE MEMBRANE STRUCTURES

2007, 37(3): 389-397. doi: 10.6052/1000-0992-2007-3-J2006-186

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Investigation on wrinkles is related with high precision requirementsand is one of the hottest topics for space membrane structures. The wrinkles arethe key factor to affect the space membrane structural surface accuracy. Itis therefore important to develop computationally effective analysis methodsto predict the performance of wrinkled membrane structures. At present, themain methods to study the wrinkles in space membrane structures are thenumerical simulation and experimental investigation. In the present paper, therecent advances of wrinkle numerical methodsfor space membrane structures are reviewed. We mainly discuss the importantand widely used analytical method of membrane wrinkling, and some suggestions for further investigation are made.

PROGRESS AND APPLICATION OF COMBINED COMPRESSION AND SHEAR WAVE LOADING TECHNIQUE

2007, 37(3): 398-408. doi: 10.6052/1000-0992-2007-3-J2005-125

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Since the invention of pressure/shear gas gun in the late 1970's,great advances have been achieved in the field of combinedpressure and shear impact loading and diagnostic techniques.The combined pressure and shear waves can disclose the dynamic shearproperty of materials directly, which offers additional informationof yield, damage evolution, failure, phase transition, interfacesliding etc. With respect to the dynamic behavior and mechanismof materials and the complete constitutive equations.This article summarizes the production methods of combinedcompression-shear plane waves, the measurement techniques, and theirapplications and advances in the investigation of pressure/shearplastic waves, dynamic high pressure constitutive equations,impact behavior of polymers, the shear wave tracing technique (SWT)and the failure of cement composites, dynamic friction response ofinterface, shock induced phase transition, and dynamic damage andfracture.

PROGRESS IN TURBULENCE/TRANSITION MODELLING

2007, 37(3): 409-416. doi: 10.6052/1000-0992-2007-3-J2006-159

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One of the effective approaches to simulating laminar-turbulent transitionflows is the transition\,\,/ turbulence modeling based on Reynolds-averagedNavier-Stokes equations. In this paper, its development is reviewed. First, we analyze the limitations of the so calledlow-Reynolds number turbulence models for transitional flows.These models, with modified damping functions for the viscous sublayer, seem to have some ability for transition prediction,while it is argued that it is just a chance coincident in numericalsimulation. Second, the correlation-based transitionmodels are discussed. These models, always constructed by considering theintermittency factor, take into account the physical mechanism of transitionin some extent, thus can model the transition procedure in several simpleflows. Unfortunately, it is not easy to make these models compatible with modernCFD methods because of the non-local variables in model equations. Thirdly,based completely on local variables, some recently proposed transitionmodels related to the new transport equations of laminar kinetic energy,transitional momentum thickness, Reynolds number and other characteristicparameters are analyzed. Finally, the future challenges are pointed out.

ADVANCES IN HIGH-ORDER ACCURATE WEIGHTED COMPACT NONLINEAR SCHEMES

2007, 37(3): 417-427. doi: 10.6052/1000-0992-2007-3-J2006-185

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The progress in the theoretical analysis of high-orderaccurate weighted compact nonlinear schemes (WCNS) and applications to thecomplicated flows is summarized in this paper. The development ofhigh-order schemes is reviewed, focusing on WCNS. WCNS are analyzed with Fourier method and asymptoticstability theory. Some explicit WCNS are used tosolve multi-dimensional complicated flows.

THE PROGRESS OF THE DOPPLER GLOBAL VELOCIMETRY

2007, 37(3): 428-442. doi: 10.6052/1000-0992-2007-3-J2005-073

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Doppler global velocimetry (DGV) uses molecular/atomicfilter principle to determine Doppler shift of light scattered fromparticles in a plane defined by a laser sheet, thus provides instantaneousmeasurements of the flow velocity in the plane. DGV has a greatpotential in the investigations in the areas of fluid mechanics,aerodynamics, and combustion, especially, in the high Mach-number flow. Thistechnique has attracted interests of many researches, as is called planar Doppler velocimetry (PDV), absorption filteredplanar Doppler velocimetry, filtered Rayleigh scattering (FRS). This paperreviews DGV in terms of its principle, structures, dataprocessing, and future development.

RESEARCH PROGRESS OF CROSS CORRELATION ALGORITHMS IN PARTICLE IMAGE VELOCIMETRY

2007, 37(3): 443-452. doi: 10.6052/1000-0992-2007-3-J2006-101

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Cross correlation algorithms in particle image velocimetry(PIV) are used to get the full field velocity information of the flowfield from the two PIV images. Such an algorithm can be implementedin the following stages: image pre-processing, area discretization,block matching, searching programs setting, image deformation predicting anddata post-processing, which are detailed in this paper with relatedresearches during the recent years being reviewed. The spatial resolution and theefficiency of the different algorithms are discussed and compared witheach other.

TERRAMECHANICS AND ITS APPLICATION IN PLANETARY EXPLORATION

2007, 37(3): 453-464. doi: 10.6052/1000-0992-2007-3-J2006-141

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Terramechanics concerns studies on the interaction between vehicles andrough terrain in off-road locomotion. The main topics include predictionof vehicle mobility performance, optimum design of mobility systems and soiltrafficability evaluation. In this paper, the methodology, testequipment and main results of terramechanics are reviewed, and the recentprogress is discussed. The paper focuses on the applications ofterramechanics theory in planetary exploration, including the design, validation of planetary rover,development and characterization of simulated soil and in situ mechanical parameter measurement of planetary soil. The possible future directions of this field are also discussed.

ADVANCES IN BIOMECHANICS RELATED WITH ARTIFICIAL KNEE REPLACEMENT

2007, 37(3): 465-471. doi: 10.6052/1000-0992-2007-3-J2006-120

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Knee is the biggest and the most complicated joint in humanbody, whose damage would cause abnormal movement of knee.The joint cartilage and meniscus would be worn out anddegenerated, and bony arthrosis would be formed at last. The daily life ofthe patient would be affected. The most popular treatmentis knee orthopaedic or replacement, while the total knee replacement would beadopted for severe damaged knee joint. As the knee replacementbecomes the most popular surgery, the researches related to knee prothesisattract more and more attentions. This paper reviews studies on thereplacement from biomechanical point of view, including the types and materials of prothesis, the theoreticaland experimental study on biomechanical properties of prothesis, theoreticalmodel of bone reconstruction, the theory and experiment of osseointegration,and the related finite element model. The existing problems related toartificial knee replacement are discussed and the futuredevelopment directions are commented.

AN APPROACH FOR SURMOUNTING “HYPERSONIC BARRIER”

2007, 37(3): 472-476. doi: 10.6052/1000-0992-2007-3-J2007-057

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Under the condition of hypersonic flight, the temperature of the air flowentering the combustion chamber of ramjet is very high. A large fraction ofthe available reactive heat of air and fuel of such high temperature will betransferred to dissociation energy of the products. When the burnt gases runover the exhaust nozzle with limited length, the dissociation energy can notbe released fully. As a result, the thrust of ramjet drops and can not meet theneeds of propulsion requirement for hypersonic flight. This effect is termed``hypersonic barrier''. For surmounting the``hypersonic barrier'', sometentative ideas are proposed. Under the condition of preserving the breathingand burning modes of existent ramjet, the catalysis is utilized to promotethe recombination of dissociation compositions during expansion in nozzle.Thus the thrust of the ramjet may be increased to the extent that therequirements of hypersonic propulsion can be met.

2007, 37(3): 477-479. doi: 10.6052/1000-0992-2007-3-J2007-091

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[中]梅凤翔 [英]MEI Feng-Xiang

2007, 37(3): 480-480. doi: 10.6052/1000-0992-2007-3-J2007-086

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2007 Vol. 37, No. 3

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