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A MICROMECHANICAL FRAMEWORK WITH AGGREGATE-MASTIC INTERFACE EFFECT FOR PREDICTING UNIAXIAL COMPRESSION CREEP OF ASPHALT MIXTURE

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Acta Mechanica Solida Sinica 2014年第3期27卷 306-314页

作者： Jun Wu xinhua yang Fan Bai Department of Mechanics Huazhong University of Science and Technology

According to the elastic-viscoelastic correspondence principle, an elastic microme- chanical framework taking the inclusion-matrix interface effect into account is extended for predicting viscoelastic properties of asphalt mixture, which is simply treated as elastic coarse aggregate inclusions periodically and isotropically embedded in a viscoelastic asphalt mastic matrix. The Burgers model is adopted for characterizing the matrix mechanical behavior, so that the homogenized relaxation modulus of asphalt mixture in compression creep is derived. After a series of uniaxial compression creep tests are performed on asphalt mastic in different temperature and stress conditions in order to determine the matrix constitutive parameters, the framework presented is validated by comparison with the experiment, and then some predictions of uniaxial compression creep behavior of asphalt mixture in different temperature and stress conditions are given.

关键词： asphalt mixture micromechanics elastic-viscoelastic correspondence principle compression creep

Effect of Randomness of Interfacial Properties on Fracture Behavior of Concrete Under Uniaxial Tension

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Acta Mechanica Solida Sinica 2018年第2期31卷 174-186页

作者： Chuanchuan Zhang xinhua yang Hu Gao School of Civil Engineering and Mechanics Huazhong University of Science and Technology Wuhan 430074 China Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment 1037 Luoyu Road Wuhan 430074 China

Interfacial transition zones （ITZs） between aggregates and mortar are the weakest parts in concrete. The random aggregate generation and packing algorithm was utilized to create a two-phase concrete model, and the zero-thickness cohesive elements with different normal distribution parameters were used to model the ITZs with random mechanical properties. A number of uniaxial tension-induced fracture simulations were carried out, and the effects of the random parameters on the fracture behavior of concrete were statistically analyzed. The results show that, different from the dissipated fracture energy, the peak load of concrete does not always obey a normal distribution, when the elastic stiffness, tensile strength, or fracture energy of ITZs is normally distributed. The tensile strength of the ITZs has a significant effect on the fracture behavior of concrete, and its large standard deviation leads to obvious diversity of the fracture path in both location and shape.

关键词： Interface transition zone Random parameter Concrete Fracture

BASIC THEOREMS IN LINEAR MICROMORPHIC THERMOELECTROELASTICITY AND THEIR PRIMARY APPLICATION

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Acta Mechanica Solida Sinica 2013年第2期26卷 161-176页

作者： Weizhong Cao xinhua yang Xiaobao Tian Department of Mechanics Huazhong University of Science and Technology State Key Laboratory of Materials Processing and Die & Mould Technology Huazhong University of Science and Technology

As a natural extension of the micromorphic continuum theory, the linear theory of micromorphic thermoelectroelasticity is developed to characterize the nano-micro scale behavior of thermoelectroelastic materials with remarkable microstructures. After the basic governing equations are given and the reciprocal theorem is deduced, both the generalized variational prin- ciple and the generalized Hamilton principle for mixed boundary-initial value problems of micro- morphic thermoelectroelastodynamics in convolution form are established. Finally, as a primary application, steady state responses of an unbounded homogeneous isotropic micromorphic thermo- electroelastic body to external concentrated loads with mechanical, electric, and thermal origins are analyzed.

关键词： micromorphic thermoelectroelasticity reciprocal theorem variational principle,concentrated load microstructure

General Kinetostatic Modeling and Deformation Analysis of a Two-Module Rod-Driven Continuum Robot with Friction Considered

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Chinese Journal of Mechanical Engineering 2023年第3期36卷 110-122页

作者： Peiyi Wang xinhua yang Xiangyang Wang Sheng Guo School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China Guangdong Provincial Key Lab of Robotics and Intelligent System Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen 518005China

Continuum robots actuated by flexible rods have large potential applications,such as detection and operation tasks in confined environments,since the push and pull actuation of flexible rods withstand tension and compressive force,and increase the structure's *** this paper,a generalized kinetostatics model for multi-module and multi-segment continuum robots considering the effect of friction based on the Cosserat rod theory is ***,the model is applied to a two-module rod-driven continuum robot with winding ropes to analyze its deformation and load *** different in-plane configurations under the external load term as S1,S2,C1,and C2 are *** a bending plane as an example,the tip deformation along thex-axis of these shapes is simulated and compared,which shows that the load capacity of C1 and C2 is generally larger than that of S1 and ***,the deformation experiments and simulations show that the maximum error ratio without external loads relative to the total length is no more than 3%,and it is no more than 4.7%under the external *** established kinetostatics model is proven sufficient to accurately analyze the rod-driven continuum robot with the consideration of internal friction.

关键词： Rod-driven continuum robot Kinetostatic model Cosserat rod theory Deformation and stiffness analysis

Heterogeneous Fracture Simulation of Three-point Bending Plain-concrete Beam with Double Notches

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Acta Mechanica Solida Sinica 2016年第3期29卷 232-244页

作者： Chuanchuan Zhang xinhua yang Hu Gao Hongping Zhu School of Civil Engineering and Mechanics Huazhong University of Science and Technology Wuhan 430074 China Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment 1037 Luoyu Road Wuhan 430074 China

Plain concrete is regarded as a two-phase material comprising randomly distributed aggregates and mortar matrix. A series of three-point bending concrete beams with symmetric or asymmetric double notches are modeled using the modified random aggregate generation and packing algorithm. The cohesive zone model is used as the fracture criterion and the cohesive el- ements are inserted into both the mortar matrix and the aggregate-mortar interfaces as potential micro-cracking zones. The dead and alive crack phenomena are studied experimentally and nu- merically; and the influences of notch location, aggregate distribution and gradation on fracture are numerically evaluated. Some important conclusions are given.

关键词： concrete beam double notches three-point bending fracture cohesive zone model

Damage Evolution and Crack Propagation in Semicircular Bending Asphalt Mixture Specimens

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Acta Mechanica Solida Sinica 2016年第6期29卷 596-609页

作者： Guowei Zeng xinhua yang Long Chen Fan Bai School of Civil Engineering and Mechanics Huazhong University of Science and Technology School of Science Wuhan University of Science and Technology

The damage and fracture behaviors of semicircular bending （SCB） asphalt mixture specimens with different orientation notches are experimentally and numerically investigated. In the numerical simulations, asphalt mixture is modeled as a two-phase material, namely a mix of coarse aggregates and asphalt mastic, and the mechanical behavior of asphalt mastic is charac- terized with the damage constitutive model and the damage-based fracture criterion. Some SCB experiments are performed on the asphalt mixture specimens with different orientation notches to validate the numerical method. Finally, the effects of notch orientation and aggregate distrib- ution on crack path, damage distribution, and the load vs. displacement relation are numerically evaluated.

关键词： semicircular bending heterogeneous model damage notch orientation

Low-level lead exposure effects on spatial reference memory and working memory in rats

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Neural Regeneration Research 2009年第1期4卷 72-76页

作者： xinhua yang Ping Zhou Yonghui Li Mental Health Center Hunan Agriculture University Changsha 410128 Hunan Province China College of Education Sciences Hunan Normal University Changsha 410081 Hunan Province China Institute of Psychology Chinese Academy of Sciences Beijing 100101 China

BACKGROUND： Studies have demonstrated that lead exposure can result in cognitive dysfunction and behavior disorders. However, lead exposure impairments vary under different experimental conditions. OBJECTIVE： To detect changes in spatial learning and memory following low-level lead exposure in rats, in Morris water maze test under the same experimental condition used to analyze lead exposure effects on various memory types and learning processes. DESIGN AND SETTING： The experiment was conducted at the Animal Laboratory, Institute of Psychology, Chinese Academy of Science between February 2005 and March 2006. One-way analysis of variance （ANOVA） and behavioral observations were performed. MATERIALS： Sixteen male, healthy, adult, Sprague Dawley rats were randomized into normal con-trol and lead exposure groups （n = 8）. METHODS： Rats in the normal control group were fed distilled water, and those in the lead exposure group were fed 250 mL of 0.05% lead acetate once per day. At day 28, all rats performed the Morris water maze test, consisting of four phases： space navigation, probe test, working memory test, and visual cue test. MAIN OUTCOME MEASURES： Place navigation in the Morris water maze was used to evaluate spatial learning and memory, probe trials for spatial reference memory, working memory test for spatial working memory, and visual cue test for non-spatial cognitive function. Perkin-Elmer Model 300 Atomic Absorption Spectrometer was utilized to determine blood lead levels in rats. RESULTS：（1） In the working memory test, the time to reach the platform remained unchanged between the control and lead exposure groups （F（1,1） = 0.007, P = 0.935）. A visible decrease in escape latencies was observed in each group （P = 0.028）. However, there was no significant difference between the two groups （F（1,1） = 1.869, P = 0.193）. The working memory probe test demonstrated no change between the two groups in the time spent in the target quadrant during the working m

关键词： lead spatial learning reference memory working memory

Water modeling of mold powder entrapment in slab continuous casting mold

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Journal of University of Science and Technology Beijing 2007年第5期14卷 399-404页

作者： Qiaotong Lu Rongguang yang xinhua Wang Jiongming Zhang Wanjun Wang Metallurgical and Ecological Engineering School University of Science and Technology Beijing Beijing 100083 China

The optimal parameters were determined by the water modeling of slab casting. It was found that there are mainly three types of mold powder entrapment in slab continuous casting, i.e., the entrapment caused by the shearing flow near the narrow face of mold, the entrapment caused by vortexes around the submerged entry nozzle （SEN）, and the entrapment caused by the Ar bubbling. Both the velocity of the surface flow and the level fluctuation of the liquids are enlarged with increasing the casting speed, reducing the submersion depth of SEN, decreasing the downward angles of the nozzle outlets, and increasing the Ar flowrate, all of which increase the tendency of mold powder entrapment. Among the four above-mentioned factors, casting speed has the largest effect.

关键词： continuous casting slab mold mold powder water model

Master-slave synchronization of singular Lur'e systems with time-delay

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控制理论与应用（英文版） 2011年第4期9卷 594-598页

作者： Zebin yang xinhua ZHANG Xiaofu JI School of Electrical and Information Engineering Jiangsu University Zhenjiang Jiangsu 212013 China

This paper is concerned with the problem of designing a time-delay output feedback control law for masterslave synchronization of singular Lur＇e systems. Using generalized Lyapunov stability theory, a sufficient condition for the existence of such feedback control law is given and an explicit expression of such control law is also achieved. These algorithms are formulated in terms of linear matrix inequalities, which can be easily performed numerically. A numerical example is used to illustrate the effectiveness of the design method.

关键词： Singular Lur'e systems Time-delay synchronization Linear matrix inequality