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A MICROMECHANICS CONSTITUTIVE THEORY FOR FORWARD TRANSFORMATION PLASTICITY WITH shear AND DILATATION effect:I,NONPROPORTIONAL LOADING HISTORY

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Acta Mechanica Sinica 1990年第4期6卷 324-332页

作者： Hwang Kehchih Sun Qingping Yu Shouwen (Department of Engineering Mechanics,Tsinghua University,Beijing,China.) Department of Engineering Mechanics Tsinghua University Beijing China

A micromechanics constitutive theory which takes into account both the dilatation and shear ef- fects of the transformation is proposed to describe the macroscopic plastic behavior of structure ceramics during forward transformation under different *** some basic assumptions,the analytic expressions of the Helmholtz and complementary free energy of the constitutive element are derived in a self-consistent manner by using the Mori-Tanaka's method which takes into account the interaction between the transformed *** the framework of Hill-Rice's internal variable constitutive theory,the forward transformation yield function and incremental stress strain relations,in analogy to the theory of metal plasticity,for non-proportional loading histories are obtained.

关键词： shear effect internal variables constitutive element

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Mechanism of nanoparticle aggregation in gas-liquid microfluidic mixing

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Chinese Chemical Letters 2024年第4期35卷 376-381页

作者： Hongxia Li Xiyang Wang Du Qiao Jiahao Li Weiping Zhu Honglin Li Key Laboratory for Precision&Non-traditional Machining Technology of Ministry of Education Dalian University of TechnologyDalian 116023China Shanghai Key Laboratory of New Drug Design School of PharmacyEast China University of Science and TechnologyShanghai 200237China

Using gas-liquid segmented micromixers to prepare nanoparticles that have a homogeneous particle size, controllable shape, and monodispersity advantages. Although nanoparticle aggregation within a microfluid has been shown to be affected by the shear effect, the shear effect triggering conditions in gasliquid two-phase flow is unclear and the aggregation behavior of nanoparticles under the shear effect is difficult to predict, resulting in uncontrollable physical and chemical properties of nanoparticle aggregates. In this study, a numerical simulation of nanoparticle aggregation in gas-liquid two-phase flow under the shear effect is performed using the CFD-DEM method. Then, the effects of total flow rate,gas-liquid two-phase flow ratio, and particle volume fraction on particle aggregation were analyzed to achieve control of particle aggregation shape and size. Meanwhile, the triggering mechanism of the shear effect and the mechanism of the shear effect on the aggregation of nanoparticles were clarified. The results show that increasing the total flow rate or decreasing the gas-liquid two-phase flow rate ratio can induce the shear effect, which reduces the particle aggregation size and makes the morphology tend to be spherical. Moreover, increasing the particle volume fraction, and total flow rate or decreasing the gas-liquid two-phase flow rate ratio also increases the number of particle collisions and induce interparticle adhesion. Hence, particle adhesion and the shear effect compete with each other and together affect particle aggregation.

关键词： Microfluidic Gas-liquid segmented micromixer Nanoparticle aggregation shear effect Numerical calculation

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Influence of shear effects on the Characteristics of Axisymmetric Wave Propagation in a Buried Fluid‑Filled Pipe

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Chinese Journal of Mechanical Engineering 2022年第3期35卷 275-284页

作者： Ping Lu Xiaozhen Sheng Yan Gao Ruichen Wang State Key Laboratory of Traction Power Southwest Jiaotong UniversityChengdu 610031China School of Urban Railway Transportation Shanghai University of Engineering ScienceShanghai 201620China Key Laboratory of Noise and Vibration Research Institute of AcousticsChinese Academy of SciencesBeijing 100190China Institute of Railway Research University of HuddersfieldHuddersfield HD13DHUK

The acoustic propagation characteristics of axisymmetric waves have been widely used in leak detection of fluid-filled *** related acoustic methods and equipment are gradually coming to the market,but their theoretical research obviously lags behind the field practice,which seriously restricts the breakthrough and innovation of this *** on the fully three-dimensional effect of the surrounding medium,a coupled motion equation of axisymmetric wave of buried liquid-filled pipes is derived in detail,a contact coefficient is used to express the coupling strength between surrounding medium and pipe,then,a general equation of motion was derived which contain the pipe soil lubrication contact,pipe soil compact contact and pipe in water and ***,the corresponding numerical calculation model is established and solved used numerical *** shear effects of the surrounding medium and the shear effects at the interface between surrounding medium and pipe are discussed in *** output indicates that the surrounding medium is to add mass to the pipe wall,but the shear effect is to add *** the consideration of the contact strength between the pipe and the medium,the additional mass and the pipe wall will resonate at a specific frequency,resulting in a significant increase in the radiation wave to the surrounding *** research contents have great guiding effect on the theory of acoustic wave propagation and the engineering application of leak detection technology in the buried pipe.

关键词： Buried fluid-filled pipe Axisymmetric waves shear effect Dispersion

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ASYMPTOTIC ANALYSIS OF PLANE-STRAIN MODE I STEADY-STATE CRACK GROWTH IN TRANSFORMATION TOUGHENINGCERAMICS(Ⅱ)

引用

Applied Mathematics and Mechanics(English Edition) 1997年第7期18卷 689-696页

作者：张浠叶裕恭 Zhongnan Institute of Technology Hengyang P. R. China Institute of Mechanics Chinese Academy of Sciences Beijing P. R. China

Based on a constitutive law which includes the shear components oftransformation plasticity. the asymptotic solutions to near-tip fields of plane-strainmode I steadity propagating cracks in rransformed ceramics are obtained for the caseof linear isotropic hardening. The Stress singularity. the distributions of stresses andvelocities at the crack tip are determmed for various material parameters. The factorsinfluencing the near-tip fields are discussed in detail.

关键词： transformation toughening ceramics shear effect crack growth,asymptotic method

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