检索结果-南通市图书馆

Speculation of fluid dynamics equations based on Liutex theory and constitutive relation of symmetric shearing deformation

引用

Journal of Hydrodynamics 2023年第4期35卷 607-629页

作者： Shuai-chen Zhu Duo Wang Yang Liu Hongyi Xu Department of Aeronautics and Astronautics Fudan UniversityShanghai200433China

The fluid kinematics of Liutex decomposes a velocity gradient tensor(VGT)of∇v into four components,including rotation(R),stretching/compressing(SC),anti-symmetric shear(Santi-sym)and symmetric shear(Ssym),as oppose to the traditional Cauchy-Stokes decomposition where a VGT was decomposed into the strain rate and vorticity tensors.The current study limpidly clarified the physical meanings of these deformations in the newly-proposed decomposition from the perspectives of both fluid kinematics and dynamics.With in-depth understanding the physical connotations of these deformations,the present study further suggests that the Ssym be the only deformation appropriately correlated to the stress tensor,leading to the establishment of a new constitutive relation for Newtonian fluids with the modified model assumptions originated from Stokes in 1845.Moreover,the present research finds that the“principal decomposition”proposed by Liu is not mathematically unique when a VGT has three real eigenvalues(TR).Within the context,a new decomposition method is introduced to avoid the non-uniqueness issue arising from using the principal decomposition to establish fluid dynamics equations.Based on the modified Stokes assumptions and the novel VGT decomposition method,a set of new fluid dynamics momentum equations are obtained for Newtonian fluid.The added stress tensor of Fadd is identified as the key difference between the newly-derived governing equations and the conventional Navier-Stokes(N-S)equations,which is caused by excluding the SC correlation to the stress tensor in the new constitutive equation.Finally,a preliminary analysis of Fadd is conducted using the existing channel turbulence direct numerical simulations(DNS)data based on the traditional N-S equations.The Fadd is found widely existing in turbulence and is of the same order of magnitude with the other force terms.Therefore,the Fadd is expected to have some nonnegligible effects on altering the current DNS data based on the traditional N-S equations,which will be furt

关键词： constitutive relation Liutex principal decomposition Newtonian fluid Navier-Stokes equations fluid kinematics fluid dynamics

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

ELASTIC-PLASTIC constitutive relation OF PARTICLE REINFORCED COMPOSITES

引用

Acta Mechanica Sinica 1999年第4期15卷 344-354页

作者：季葆华王自强 LNM Institute of Mechanics Chinese Academy of Sciences Beijing China 100080

In this paper, a systematic approach is proposed to obtain the macroscopic elastic-plastic constitutive relation of particle reinforced composites (PRC). The strain energy density of PRC is analyzed based on the cell model, and the analytical formula for the macro-constitutive relation of PRC is obtained. The strength effects of volume fraction of the particle and the strain hardening exponent of matrix material on the macro-constitutive relation are investigated, the relation curve of strain versus stress of PRC is calculated in detail. The present results are consistent with the results given in the existing references.

关键词： cell model elastic-plastic constitutive relation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

New constitutive relation for eddy viscosity models

引用

航空动力学报 2016年第10期31卷 2485-2492页

作者： JIANG Li-jun GAO Ge Hunan Aviation Powerplant Research Institute Aero Engine Corporation of China School of Energy and Power Engineering Beijing University of Aeronautics and Astronautics

A new turbulent constitutive relation was directly derived from Boussinesqs hypothesis and mixing length theory,and then implemented in the standard k-ε model.The performance of this constitutive relation was validated in zero pressure gradient flat-plate boundary layer flow,fully-developed turbulent channel flow and separated flow in a plane asymmetric diffuser.The investigation demonstrated that,this new constitutive relation gave very accurate results in the former two basic cases and provided significant improvement in prediction of separated and reattachment points in the plane asymmetric diffuser.Separation and reattachment points at x/H =7.5and 29 were calculated accurately in comparison to experimental results,and the static pressure coefficient of 0.82 was very close to large eddy simulation calculation.These results are very encouraging but further verification and extensive application of the new constitutive relation to other two-equation eddy viscosity model are needed.

关键词： constitutive relation turbulence model flat-plate flow channel flow separated flow

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

One-dimensional Incremental constitutive relation of SMA Wire Reinforced Smart Composites with Damages

引用

Journal of Materials Science & Technology 2008年第5期24卷 729-732页

作者： Zili HU Wanlin ZHOU Institute of Unmanned Aircraft Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

A new Martensitic transformation kinetic model for shape memory alloy （SMA） is proposed based on the phenomenological description of the Martensitic transformation heat flow-temperature curve and on the linear relationship between the partial derivatives of Martensite fraction and of Gbbis free energy with respect to the temperature. A meso-mechanical model is developed to describe the longitudinal stiffness reduction and thermo-dilatation variation of the composites caused by fiber breaking or fiber peeling off the base material. One-dimensional incremental constitutive relation is then established for SMA wire reinforced smart composites with damages by introducing three parameters to respectively describe the extent of fiber breaking, fiber peeling off the base material and interface weakening. The results presented herein may provide a theoretical basis for further studying on SMA smart composites with damages.

关键词： Smart composites constitutive relation Meso-mechanical model Damages SMA Martensitic transformation Kinetic model

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The constitutive relation of a Fabric Membrane Composite for a Stratospheric Airship Envelope Based on Invariant Theory

引用

Computers, Materials & Continua 2017年第2期53卷 73-89页

作者： Junhui Meng Mingyun Lv College of Engineering China Agricultural UniversityBeijing 100083PR China School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191PR China.

The study of stratospheric airships has become the focus in many countries in recent years,because of its potential applications in many fields.Lightweight and high strength envelopes are the keys to the design of stratospheric airships,as it directly determines the endurance flight performance and loading deformation characteristics of the airship.A typical envelope of any stratospheric airship is a coated-fabric material which is composed of a fiber layer and several functional membrane layers.According to composite structure,nonlinearity and viscoelasticity are the two main characteristics of such envelope.Based on the analysis on the interaction between the different components in the micro-mechanical model of the coated-fabric,several invariant values reflecting the characteristics of the envelope material are obtained according to invariant theory.Furthermore,the constitutive equation that describes the viscoelasticity of the envelope material is derived.The constitutive equation can represent both the individual roles of the warp and weft fibers,and their further coupled interactions.The theoretical computation results were verified by off-axial tension tests.The results can help gain a deeper understanding of the mechanical mechanism and provide a reference for structural design of envelope material.

关键词： Stratospheric airship fabric membrane composite constitutive relation invariant theory viscoelasticity.

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Research on Bond-Slip constitutive relation for Steel Reinforced Concrete Members

引用

Journal of Beijing Institute of Technology 2009年第2期18卷 152-156页

作者：梁斌孟凡深刘俊玲 College of Architectural Engineering Henan University of Science and Technology Department of Civil Engineering Luoyang Institute of Science and Technology

The constitutive relation of bond-slip on steel and concrete interface is proposed for short steel reinforced concrete （SRC） column. Based on the experimental research on bond-slip performance, a mechanical model of short SRC column in pulling or pushing test is established. By means of the elasto-plasticity theory the explicit formulation of bond-slip constitutive relation τ-s in different anchor-hold place of push and pull member is investigated under the conditions of balance and boundary. The study shows that the constitutive relation is relevant to the embedment length and the thickness of concrete cover. The results are continuous descriptions of bond-slip constitutive relation and can be used to analyze the non-linear performance of SRC members. Results indicate that the principle of the method is correct and it performs well for short SRC column.

关键词： steel reinforced concrete （SRC） bond-slip constitutive relation pushing and pull member

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A constitutive relation FOR PSEUDO-ELASTIC BEHAVIOUR IN SHAPE MEMORY ALLOYS

引用

Acta Mechanica Sinica 1991年第1期7卷 67-75页

作者： Zhigang, Wang Kehchih, Hwang Tsinghua University China

A constitutive relation to describe pseudo-elastic deformation in shape memory alloys is pres- ented in this paper. It is capable of describing deformation behaviour of polycrystalline materials under triaxial stress state as well as of monocrystalline materials under one-dimensional condition. Total strain rate is sup- posed to be composed of elastic strain rate and transformation strain rate. Deformation behaviour of Cu-Zn-Sn alloy and Ti-Ni alloy is simulated by use of the proposed constitutive relation. It is shown that simulated results are in a good agreement with experimental data.

关键词： constitutive relation shape memory alloys pseudo-elasticity phase transfonnations

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Heterogeneous anisotropic complex structure gradual model and constitutive relation

引用

Chinese Physics B 2003年第11期12卷 1187-1193页

作者：李永宋健张志民 StateKeyLaboratoryofAutomotiveSafetyandEnergy TsinghuaUniversityBeijing100084China CenterofPhysics BeijlngUniversityofAeronauticsandAstronauticsBeijing100083China

Four new gradually delaminate models of the three-dimensional macro-/mesoscopic structure and delamination of the heterogeneous anisotropic composite (HAC) are set up by conducting research into its structure and performance. A general theory, which demonstrates the three-dimensional constitutive relation of the macro-/mesoscopic performance of this structure is further developed. The macroscopic expression of HAC is presented in terms of a Tanigawa delaminate homogeneous equivalent approach, the mesoscopic problems are analysed utilizing Eshelby-Mori-Tanaka theory, with the introduction of the representative volume elements of monolayer single unit cell and interlaminar double unit cells.According to the gradual continuity of the structure as a whole, great attention is given to the modelling and research of the interlaminar macroscopic and mesoscopic problems of HAC structure. Comparison with the existing solutions is made through calculation of typical cases.

关键词： HAC constitutive relation mesoscopic Tanigawa approach

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Alternative constitutive relation for momentum transport of extended Navier–Stokes equations

引用

Chinese Physics B 2020年第12期29卷 340-345页

作者：韩国锋刘晓丽黄进 Kumar Nawnit 孙亮 Institute of Mechanics Chinese Academy of SciencesBeijing 100190China State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing 100084China PetroChina Research Institute of Petroleum Exploration&Development Beijing 100083China

The classical Navier–Stokes equation(NSE)is the fundamental partial differential equation that describes the flow of fluids,but in certain cases,like high local density and temperature gradient,it is inconsistent with the experimental results.Some extended Navier–Stokes equations with diffusion terms taken into consideration have been proposed.However,a consensus conclusion on the specific expression of the additional diffusion term has not been reached in the academic circle.The models adopt the form of the generalized Newtonian constitutive relation by substituting the convection velocity with a new term,or by using some analogy.In this study,a new constitutive relation for momentum transport and a momentum balance equation are obtained based on the molecular kinetic theory.The new constitutive relation preserves the symmetry of the deviation stress,and the momentum balance equation satisfies Galilean invariance.The results show that for Poiseuille flow in a circular micro-tube,self-diffusion in micro-flow needs considering even if the local density gradient is very low.

关键词： extended Navier-Stokes equation constitutive relation momentum transport mass diffusion

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Analysis of Bonding Properties of Corroded Reinforcement Concrete

引用

Journal of Architectural Research and Development 2024年第3期8卷 80-92页

作者： Liang Fang Yingzhuo Liu College of Water Resources&Civil Engineering Hunan Agricultural UniversityChangsha 410128Hunan ProvinceChina

In order to investigate the degradation of bonding properties between corroded steel bars and concrete,this study employs the half-beam method to conduct bond-slip tests between corroded steel bars and concrete after impressed-current accelerated corrosion of the steel bars in concrete.The effects of steel corrosion rate,steel bar diameter,steel bar strength grade,and concrete strength grade on the bonding properties between concrete and corroded steel bars were analyzed.The influence of different corrosion rates on specimens’bonding strength and bond-slip curves was determined,and a constitutive relationship for bond-slip between corroded steel bars and concrete was proposed.The results indicate that the ultimate bonding strength of corroded reinforced concrete specimens decreases with increasing corrosion rate.Additionally,an increase in corrosive crack width leads to a linear decrease in bonding strength.Evaluating the decline in adhesive properties through rust expansion crack width in engineering applications is feasible.Furthermore,a bond-slip constitutive relationship between corroded steel bars and concrete was established using relative bond stress and relative slip values,which aligned well with the experimental findings.

关键词： Corrosion Reinforced concrete Bonding property constitutive relation

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：