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2005 Vol. 35, No. 4

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2005, 35(4): 465-466. doi: 10.6052/1000-0992-2005-4-J2005-137
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2005, 35(4): 467-471. doi: 10.6052/1000-0992-2005-4-J2005-138
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CARPAL TUNNEL SYNDROME AND BIO-MECHANICAL STUDIES ON CTS
2005, 35(4): 472-480. doi: 10.6052/1000-0992-2005-4-J2005-054
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Carpal tunnel syndrome (CTS)is defined as anentrapment neuropathy of the median nerve, and its high social and economiccosts lead to a surge of studies,especially during the past ten years. This article first reviews normalanatomy of carpal tunnel, symptoms, causal factors and compression mechanismof CTS, and the diagnosis and treatment available for CTS patients. Then itgives a detailed review of the biomechanical studies related to carpaltunnel syndrome from the following aspects: (1) Factors affecting the carpaltunnel pressure, such as different wrist postures, loads on finger tips ortendons or palms, and the frequency of wrist movement in repetitive handactivities; (2) Carpal stability, such as the influence of incising thetransverse carpal ligament or some transverse intercarpal ligament on carpalstiffness, and the loss of stability caused by the open carpal tunnelrelease as viewed in kinetics; (3) Movements and interactions between thedigital flexor tendons, median nerve and transverse carpal ligament; (4)Lengthening of transverse carpal ligament by sustained tensile loads orusing the transposition flap technique. The objective of this paper is toprovide a basic understanding of CTS and to introduce the biomechanicalstudies that have been carrived out related to the CTS. It is suggested that one ofpromising aspects in biomechanical studies of CTS may lie in the use offinite element (FE) methods to set up three-dimensional models of the wristand the hand and to analyze the carpal tunnel by biomechanics.
NUMERICAL SOLUTIONS OF THE DIFFUSION PARABOLIZED NAVIER-STOKES EQUATIONS
2005, 35(4): 481-497. doi: 10.6052/1000-0992-2005-4-J2004-060
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In the late 1960's the different-type simplifiedNavier-Stokes models, or as are generally called, the diffusionparabolized N-S (DPNS) equations,and their computational methods developed from the Prandtl's boundary-layertheory have correctly included the viscous-inviscid flow interacting mechanismand opened a new approach for simulating large-scale complex flowfields. Thispaper reviews the related main results of this field, includingadvantages and drawbacks of different simplified Navier-Stokes models;mathematical characteristics and their marching regularization procedures of theDPNS equations; various representative numerical solutions and theapplicability of the DPNS equations and finally the new generalized DPNSequations.
ADVANCES OF VIBRATION LOCALIZATION IN DISORDERED PERIODIC STRUCTURES
2005, 35(4): 498-512. doi: 10.6052/1000-0992-2005-4-J2004-154
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Periodic structures find many practical applicationsin engineering. They have special dynamiccharacters such as frequency passbands and stopbands. Disorder canresult in radical changes of their mechanical properties.In disordered periodic structures, one may see vibration localization.Localization destroys the regularities of vibration modes ofperiodic structures and some parts of the structures may have very largevibration amplitudes under external excitations. This may lead to energyaccumulation oreven destroy the structures. So it is very important to analyze thepropagation characteristics of vibration and energy in disordered periodicstructures, which can provide theoretical bases for the vibration controland vibration reduction of substructures. This paperreviews the current development of the investigations on the vibrationlocalization in one-dimensional linear periodic structures, cyclic periodicand two-dimensional periodic structures. The discussion is focused on theestablishment of mechanical models, analytical methods and other issuesin vibration localization. Finally,some problems for further studies are suggested.
ADVANCES OF RESEARCH ON BIFURCATIONS AND CHAOS IN VIBRO-IMPACT SYSTEM
2005, 35(4): 513-524. doi: 10.6052/1000-0992-2005-4-J2004-085
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The vibro-impact system found in many practicalsystems, as a typical non-smooth dynamical system is importantin engineering. Its studies include theoretical analysis, numericalsimulations, applied and experimental studies. By establishing thePoincar\'{e} map, using the center manifold theorem and the theory of normalforms, the periodic motion stability, bifurcation and chaos of the vibro-impactsystem can be investigated. The theory of bifurcation and chaos of map isone of the bases in studying vibro-impact systems. The smooth nonlinear dynamics canbe partly extended to vibro-impact systems, but the discontinuity caused byimpact will affect applicability and effectiveness of some methods.The theoretical studies and engineering applications of stability,bifurcations, chaos and singularity of vibro-impact systems are surveyedin this paper. Finally, the discussion centers around some unsolved problemsof bifurcations and chaos of vibro-impact systems, and the advance in thecorresponding discrete map dynamics. The future research trends aresuggested.
A REVIEW ON GRAIN BOUNDARY EFFECTS IN SUPERPLASTICITY
2005, 35(4): 525-540. doi: 10.6052/1000-0992-2005-4-J2004-073
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Since superplasticity wasdiscovered in 1934, muchattention has been paid to its special deformation mechanisms. In thispaper, with the investigation on grain boundaries being taken as themain thread, some newdevelopments are summarized from a viewpoint of mechanics, including the modelsbased on the grain boundary topological structure, statistical law and energydissipation theory. Superplastic intergranular fracture due to the grainboundary void damage and relationships between grain boundary structurechanges and macroscopic rate-sensitivity are addressed. Typical numericalmodels for superplastic deformation simulations are enumerated, withconsiderations of grain boundary effects. Some importantexperimental methods measuring the grain boundary sliding are reviewed anddiscussed. Finally, we suggest some future directions insuperplasticity, including multi-scale coupled superplastic mechanics,applications of superplastic properties in material preparations andSPF/DB fabrication process.
2005, 35(4): 541-548. doi: 10.6052/1000-0992-2005-4-J2004-105
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Made of high strength-low density fibers and amatrix, the fibrous composite enjoys many excellent properties or specialcharacteristics and finds wide applications. The mechanical properties ofcomposite materials are correlated with the manufacturing process, and theirdiversity is generally larger than that of metals, so the reliabilityanalysis is important. Designability is anotherfeature of composites, which makes it possible to optimize acomposite structure. This paper discusses the reliability, optimum design,reliability-based optimization and robust optimization for laminatedcomposites, and some suggestions are made for future research.
RECENT PROGRESS IN STATISTICS OF TURBULENT PASSIVE SCALAR
2005, 35(4): 549-558. doi: 10.6052/1000-0992-2005-4-J2004-125
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The passive scalar statistics are important in turbulencetheories and engineering problems related to turbulent combustion, pollutantdiffusion and others. Since the 1980s, studies of passive scalar have been oneof hotspots in the turbulence research. Experiments and numerical simulationshave revealed many new phenomena and concepts, which make itnecessary toreinterpret the classical turbulent theories and modify applicationmodels. This paper gives a review of the recent developments, including theanisotropy of passive scalar field, PDF of scalar and scalar dissipation,dynamics of small-scale structure and scalar mixing model etc.
STUDY ON GAS KINETIC NUMERICAL ALGORITHM USING BOLTZMANN MODEL EQUATION
2005, 35(4): 559-576. doi: 10.6052/1000-0992-2005-4-J2004-072
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Based on the kinetic Shakhov model equation, a unifiedsimplified velocity distribution function equation describing gas transportphenomena for various flow regimes is proposed. The discrete velocityordinate technique is studied and applied to the velocity distributionfunction equation. With the decoupling technique of the DSMC methodand the unsteady time-splitting method, the gas-kinetic finite differencemethod for directly solving the velocity distribution functions isestablished by coupling and iteration. The discrete velocitynumerical integration methods are developed and applied to evaluate themacroscopic flow parameters at each point in the physical space. As aresult, a unified simplified gas-kinetic numerical algorithm is obtained for flows from rarefied transition to continuum. To test thepresent method, one-dimensional shock structure problems,two-dimensional flows past cylinder, and three-dimensional flows aroundsphere with various Knudsen numbers are simulated. The computational resultswith high resolution of the flow fields are found in good agreement with thetheoretical, DSMC, N-S and experimental data. The computing resultsconfirm a good precision and reliability of the algorithm in solving thegas dynamical problems from rarefied flow to continuum. The HPF parallelstrategy is studied for the gas-kinetic numerical method. The gas flowsaround three-dimensional sphere and spacecraft-like shape with variousKnudsen numbers are computed with massive scale parallel schemes. A good parallel efficiency and speed-up ratio have been found so that itis practical and possible that an HPF parallel algorithm can bedeveloped for solvingthree-dimensional complex problems in various flow regimes. The gas kinetic algorithm is extended and applied to study themicro -channel gas flows. The numerical algorithm is developed for thegas flows in two-dimensional short micro-channels with various Knudsennumbers. The classical Couette flows, the pressure-driven plane Poiseuilleflow, and the pressure-driven gas flows in two-dimensional shortmicro-channels are simulated and compared with the approximatesolutions of the linear Boltzmann equation, the related DSMC results, themodified N-S solutions with slip-flow boundary, and the experimentaldata. The numerical experience shows that the gas kinetic algorithm may be apowerful tool in the numerical simulation of micro-scale gas flows in theMicro-Electro-Mechanical System (MEMS).
ADVANCES OF ACTIVE FLOW CONTROL BASED ON MEMS TECHNOLOGY
2005, 35(4): 577-584. doi: 10.6052/1000-0992-2005-4-J2004-122
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Active flow control isrelated to the flowmechanism and aircraft researches with real time anddynamic features. It becomes possible only after the applications ofMEMS technology MEMS technology has opened a newterritory for active flow control, and considerably accelerated the progressof active flow control technology. The fundamental principle, the keytechnologies and the mechanism that how and where MEMS could be used inactive flow controls are discussed briefly in this paper.Advances of micro-sensor, micro-controller, micro-actuator, integrationtechnologies, and their applications such as to leading edge separationvortices of delta wing, to drag reduction, to jet flow and to separationflow of slender bodies are reviewed. All of these showthe merits of active flow control based MEMS, and the potential military andindustry uses.
Coupling research on tiop mechanics and surface physicochemistry
2005, 35(4): 585-599. doi: 10.6052/1000-0992-2005-4-J2004-130
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Since the invention of scanning probe microscopy, it ispossible in reality to explore the ultrastructures with a resolutiondown to nanometer, molecule and atom scales, to probe mechanical, electrical,magnetical and complex chemical and physical properties, and to manipulatesingle atom and molecule. From the view point of coupling of probetechniques and surface chemical, physical and mechanical properties, theresearch field of probe's chemical and physical mechanics is summarized inthis paper, and several important methods about chemically modified tips areintroduced, which include using metal films, molecular self-assembly films,colloidal spheres and carbon nanotubes. And then several active researchfields are presented. These fieldsinclude theoretical descriptions and experimental measurements of surfaceand intermolecular forces which mainly involve Van der Waals, double layer,hydrophobic, Casimir and Single-Bond forces, and also involve theapplications of probe techniques related to mechanics of chemical forcetitration, surface chemical recognition and so on. The effect of tip andsubstrate materials on the resulting force is also discussed. Because thesecomplex interactions and physical, chemical, mechanical and biologicalproperties within atoms and molecules can be measured by a tiny tip, we firstput forward the concept of tip mechanics in this paper. Finally,it is pointed out that probe chemical and physical mechanics combined withmultiple fieldswill become an attractive interdisciplinary research field of mechanics.
2005, 35(4): 600-604. doi: 10.6052/1000-0992-2005-4-J2005-128
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2005, 35(4): 605-610. doi: 10.6052/1000-0992-2005-4-J2005-127
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2005, 35(4): 611-612. doi: 10.6052/1000-0992-2005-4-J2005-087
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2005, 35(4): 613-613. doi: 10.6052/1000-0992-2005-4-J2005-097
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2005, 35(4): 614-615. doi: 10.6052/1000-0992-2005-4-J2005-077
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2005, 35(4): 616-616. doi: 10.6052/1000-0992-2005-4-J2004-186
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Contents of Advances in Mechanics,Vol.35,2005
2005, 35(4): 617-620. doi: 10.6052/1000-0992-2005-4-J2005-147
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Subject Index to Advances in Mechanics,Vol.35,2005
2005, 35(4): 621-624. doi: 10.6052/1000-0992-2005-4-J2005-148
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