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| 1 | Representation of the constitutive equation of viscoelastic materials by the generalized fractional element networks and its generalized solutions显示文摘The generalized fractional element networks are presented in this paper. In order to extend the structure of the model solutions to the generalized function space and make it contain more physical meanings, the restriction on the parameters of the fractional element proposed by Schiessel et al. is eliminated and a 'compatibility equation' is added. The discretization method for solving the inverse Laplace transform is used and developed. The generalized solutions of the model equations are given. At the same time the generalized fractional element network--Zener and Poyinting-Thomson models are discussed in detail. It is shown that all the results obtained previously about the models of single parameter with fractional order and the classical models with integer order can be contained as the special cases of the results of this paper. | 徐明瑜 谭文长 | 2003 | Science China(Physics,Mechanics & Astronomy)2003，46，2： | 25 |
| 2 | Deformation and failure mechanism of slope in three dimensions显示文摘Understanding three-dimensional(3D)slope deformation and failure mechanism and corresponding stability analyses are crucially important issues in geotechnical engineering.In this paper,the mechanisms of progressive failure with thrust-type and pull-type landslides are described in detail.It is considered that the post-failure stress state and the pre-peak stress state may occur at different regions of a landslide body with deformation development,and a critical stress state element(or the soil slice block)exists between the post-failure stress state and the pre-peak stress state regions.In this regard,two sorts of failure modes are suggested for the thrust-type and three sorts for pull-type landslides,based on the characteristics of shear stress and strain(or tensile stress and strain).Accordingly,a new joint constitutive model(JCM)is proposed based on the current stability analytical theories,and it can be used to describe the mechanical behaviors of geo-materials with softening properties.Five methods,i.e.CSRM(comprehensive sliding resistance method),MTM(main thrust method),CDM(comprehensive displacement method),SDM(surplus displacement method),and MPM(main pull method),for slope stability calculation are proposed.The S-shaped curve of monitored displacement vs.time is presented for different points on the sliding surface during progressive failure process of landslide,and the relationship between the displacement of different points on the sliding surface and height of landslide body is regarded as the parabolic curve.The comparisons between the predicted and observed load e displacement and displacement e time relations of the points on the sliding surface are conducted.The classi fi cation of stable/unstable displacement e time curves is proposed.The de fi nition of the main sliding direction of a landslide is also suggested in such a way that the failure body of landslide(simpli fi ed as'collapse body')is only involved in the main sliding direction,and the strike and the dip are the same as the collapse body.The rake angle is taken as the direction of the sum of sliding forces or the sum of displacements in collapse body,in which the main slip direction is dependent on progressive deformation.The reason of non-convergence with fi nite element method(FEM)in calculating the stability of slope is also numerically analyzed,in which a new method considering the slip surface associated with the boundary condition is proposed.It is known that the boundary condition of sliding surface can be described by perfect elasto-plastic model(PEPM)and JCM,and that the stress and strain of a landslide can be described properly with the JCM. | Yingfa Lu | 2015 | Journal of Rock Mechanics and Geotechnical Engineering2015，7，2： | 17 |
| 3 | Research on nonlinear constitutive relationship of permanent deformation in asphalt pavements显示文摘To predict correctly the rut depths in asphalt pavements,a new nonlinear viscoelastic-elastoplastic constitutive model of permanent deformation in asphalt pave-ments is presented. The model combines a generalized Maxwell model with an elasto-plastic one. Then from the creep theory,the linear and nonlinear constitutive equations of the generalized Maxwell model are obtained. From the nonlinear finite element method for the rutting of the asphalt pavement,the rut depths of 4 asphalt-aggregate mixtures are obtained. And the results are compared with the ones from the finite element method by SHRP and the experiments by SWK/UN. The results in this paper are better than the ones by SHRP,and agree with the ones of the experiment by SWK/UN. This shows that the nonlinear viscoelastic-elastoplastic constitutive model,which is presented in this paper for the rutting of the asphalt pavement,is effective. The properties,such as nonlinear elastic-ity,plasticity,viscoelasticity and nonlinear viscoelasticity,which affect the rutting of an asphalt pavement,can be shown in the model. And the characteristics of the permanent deformation of the asphalt pavement can be presented entirely in the model. | PENG Miaojuan1 & XU Zhihong2 1. Department of Civil Engineering,Shanghai University,Shanghai 200072,China 2. School of Transportation Engineering,Tongji University,Shanghai 200092,China | 2006 | Science China(Physics,Mechanics & Astronomy)2006，49，6： | 16 |
| 4 | Review of collapse triggering mechanism of collapsible soils due towetting显示文摘Loess soil deposits are widely distributed in arid and semi-arid regions and constitute about 10% of land area of the world.These soils typically have a loose honeycomb-type meta-stable structure that is susceptible to a large reduction in total volume or collapse upon wetting.Collapse characteristics contribute to various problems to infrastructures that are constructed on loess soils.For this reason,collapse triggering mechanism for loess soils has been of significant interest for researchers and practitioners all over the world.This paper aims at providing a state-of-the-art review on collapse mechanism with special reference to loess soil deposits.The collapse mechanism studies are summarized under three different categories,i.e.traditional approaches,microstructure approach,and soil mechanics-based approaches.The traditional and microstructure approaches for interpreting the collapse behavior are comprehensively summarized and critically reviewed based on the experimental results from the literature.The soil mechanics-based approaches proposed based on the experimental results of both compacted soils and natural loess soils are reviewed highlighting their strengths and limitations for estimating the collapse behavior.Simpler soil mechanics-based approaches with less parameters or parameters that are easy-to-determine from conventional tests are suggested for future research to better understand the collapse behavior of natural loess soils.Such studies would be more valuable for use in conventional geotechnical engineering practice applications. | Ping Li Sai Vanapalli Tonglu Li | 2016 | Journal of Rock Mechanics and Geotechnical Engineering2016，8，2： | 15 |
| 5 | Dynamic mechanical behavior and the constitutive model of concrete subjected to impact loadings显示文摘Based on the theory of consecutive damage mechanics, micro-mechanics, statis-tics and the visco-plastic constitutive equation of Perzyna, a coupled model of damage and plasticity is developed to describe the complex behavior of concrete subjected to impact loadings. In this model, some suppositions about deformation of the material and evolution of the damage are made. First, concrete is macro-scopically assumed to be homogeneous and consecutive, while it is microscopi-cally filled with large amounts of micro-crack and micro-void defects. Second, the damage evolution of the micro-cracks is caused by the nucleation, growth and coalescence of the micro-cracks due to the interior tensile stress in concrete, which leads to a degradation in the strength and stiffness of concrete. Third, compaction of concrete is physically a collapse of the material micro-void. It pro-duces irreversible plastic strains in the material and, at the same time, an increase in the bulk modulus. Fourth, there is no interaction between the micro-crack and the micro-void. Last, when the damage reaches a critical value, the concrete may fail totally. The model parameters for concrete are determined by plate impact ex-periments. The model predictions fit the experimental results well. So the model can be used to simulate the dynamic mechanical behavior of concrete under impact loadings. | NING JianGuo LIU HaiFeng SHANG Lin | 2008 | Science China(Physics,Mechanics & Astronomy)2008，51，11： | 12 |
| 6 | Fracture characteristics of concrete subjected to impact loading显示文摘This paper takes concrete as a four-phase composite made of the intact matrix and three mutually perpendicular groups of penny-shaped micro-cracks. The intact matrix is assumed to be elastic,homogeneous and isotropic,and the micro-cracks are penny-shaped. Combined with the failure mechanism of concrete subjected to impact loading,a dynamic constitutive model for concrete is developed based on Mori-Tanaka's average stress concept and Eshelby's equivalent inclusion theory. Experimental results show that concrete is rate-dependent. The model predictions are in good agreement with the experimental results. The model may be used to simulate the mechanical behavior of concrete under impact loadings. | LIU HaiFeng1,2,LIU HaiYan3 & SONG WeiDong1 1 State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology,Beijing 100081,China 2 School of Civil and Hydraulic Engineering,Ningxia University,Yinchuan 750021,China 3 School of Science,Beijing Institute of Technology,Beijing 100081,China | 2010 | Science China(Physics,Mechanics & Astronomy)2010，53，2： | 12 |
| 7 | A new elliptic-parabolic yield surface model revised by an adaptive criterion for granular soils显示文摘An adaptive criterion for shear yielding as well as shear failure of soils is proposed in this paper to address the fact that most criteria,including the Mohr-Coulomb criterion,the Lade criterion and the Matsuoka-Nakai criterion,cannot agree well with the experimental results when the value of the intermediate principal stress parameter is too big.The new criterion can adjust an adaptive parameter based on the experimental results in order to make the theoretical calculations fit the test results more accurately.The original elliptic-parabolic yield surface model can capture both soil contraction and dilation behaviors.However,it normally over-predicts the soil strength due to its application of the Extended Mises criterion.A new elliptic-parabolic yield surface mode is presented in this paper,which introduces the adaptive criterion in three-dimensional principal stress space.The new model can well model the stress-strain behavior of soils under general stress conditions.Compared to the original model which can only simulate soil behavior under triaxial compression conditions,the new model can simulate soil behaviors under both triaxial compression conditions and general stress conditions. | LIU HanLong 1,2 ,XIAO Yang 1,2 ,LIU JinYuan 3 &LI GuoYing 4 1 Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering,Hohai University, Nanjing 210098,China 2 Geotechnical Research Institute,Hohai University,Nanjing 210098,China 3Department of Civil Engineering,Ryerson University,Toronto,Canada 4 Department of Geotechnical Engineering,Nanjing Hydraulic Research Institute,Nanjing 210014,China | 2010 | Science China(Technological Sciences)2010，53，8： | 12 |
| 8 | A Novel Constitutive Equation for Viscoelastic-Thixotropic Fluids and its Application in the Characterization of Blood Hysteresis Loop显示文摘1 INTRODUCTIONIt is well known that viscoelasticity and thixotropy of fluids are often investigated by measuringhysteresis loops under transient conditions.For some fluids(such as blood),it has been provedthat,an“8”shaped hysteresis loop may be obtained if triangular steps of shear rate wereapplied on it(Fig.l).This kind of hysteresis loop is composed of a viscoelastic loop and athixotropic loop.The viscoelastic and thixotropic properties are unified in the formation ofthe hysteresis loop.How to describe the formation of this complex hysteresis loop and how | 方波 江体乾 | 1998 | Chinese Journal of Chemical Engineering1998，6，3： | 10 |
| 9 | Asymptotic state behaviour and its modeling for saturated sand显示文摘A new double hardening elasto-plastic model is proposed in this paper based on the existing unified hardening model (UH model). By assuming that there is part coupling effect between the plastic volumetric strain and plastic shear strain, hardening parameters consisting of a coupled and an uncoupled components are adopted in this model. A unique feature of this model is that it can describe not only the conventional drained and undrained behaviors of soil, but also the stress-strain relationships of soil under partially drained conditions which can be volumetric compression or dilation. Adopting the asymptotic state concept, simple equations for estimating the limiting stress ratio under undrained or earth pressure at rest (i.e. K0) conditions are derived. The new model is relatively simple to be adopted in practice for two reasons. First, the same soil parameters as in Cam-clay model are used except the addition of one extra parameter, the stress ratio at the characteristic state. Second, all the parameters can be determined using conventional triaxial compression tests. | LUO Ting YAO YangPing CHU Jian | 2009 | Science China(Technological Sciences)2009，52，8： | 10 |
| 10 | A brief history of the discovery of PXR and CAR as xenobiotic receptors显示文摘The nuclear receptors pregnane X receptor(PXR) and constitutive androstane receptor(CAR) were cloned and/or established as xenobiotic receptors in 1998.Due to their activities in the transcriptional regulation of phase I and phase II enzymes as well as drug transporters,PXR and CAR have been defined as the master regulators of xenobiotic responses.The discovery of PXR and CAR provides the essential molecular basis by which drugs and other xenobiotic compounds regulate the expression of xenobiotic enzymes and transporters.This article is intended to provide a historical overview on the discovery of PXR and CAR as xenobiotic receptors. | Jiong Yan Wen Xie | 2016 | Acta Pharmaceutica Sinica B2016，6，5： | 9 |
| 11 | Genome-wide Dissection of Co-selected UV-B Responsive Pathways in the UV-B Adaptation of Qingke显示文摘Qingke (Tibetan hulless barley) has long been cultivated and exposed to long-term and strong UV-B radiation on the Tibetan Plateau, which renders it an ideal species for elucidating novel UV-B responsive mechanisms in plants. Here we report a comprehensive metabolite profiling and metabolite-based genome-wide association study (mGWAS) using 196 diverse qingke and barley accessions. Our results demonstrated both constitutive and induced accumulation, and common genetic regulation, of metabolites from different branches of the phenylpropanoid pathway that are involved in UV-B protection. A total of 90 significant mGWAS loci for these metabolites were identified in barley-qingke differentiation regions, and a number of high-level metabolite trait alleles were found to be significantly enriched in qingke, suggesting co-selection of various phenylpropanoids. Upon dissecting the entire phenylpropanoid pathway, we identified some key determinants controlling natural variation of phenylpropanoid content, including three novel proteins, a flavone C-pentosyltransferase, a tyramine hydroxycinnamoyl acyltransferase, and a MYB transcription factor. Our study, furthermore, demonstrated co-selection of both constitutive and induced phenylpropanoids for UV-B protection in qingke. | Xingquan Zeng Hongjun Yuan Xuekui Dong Meng Peng Xinyu Jing Qijun Xu Tang Tang Yulin Wang Sang Zha Meng Gao Congzhi Li Chujin Shu Zexiu Wei Wangmu Qimei Yuzhen Basang Jiabu Dunzhu Zeqing Li Lijun Bai Jian Shi Zhigang Zheng Sibin Yu Alisdair R.Fernie Jie Luo Tashi Nyima | 2020 | Molecular Plant2020，13，1： | 9 |
| 12 | Constitutive model for methane desorption and diffusion based on pore structure differences between soft and hard coal显示文摘This paper aims to improve the accuracy and applicability of gas diffusion mathematical models from coal particles. Firstly, a new constitutive model for gas diffusion from coal particles with tri-disperse pore structure is constructed by considering the difference in characteristics between soft coal and hard coal.The analytical solution is then derived, that is, the quantitative relationship between gas diffusion rate(Qt/Q_∞) and diffusion time(t), The pore structure parameters of soft coal and hard coal from Juji coal mine are determined. Gas diffusion rules are numerically calculated and investigated by physical simulation methods. Lastly, the applicability of this model is verified. The results show that the homogeneous model only applies to the gas diffusion process of hard coal during the initial 10 min. The calculation results from this model and the physical experimental results of soft coal and hard coal are nearly identical during the initial 30 min. | Liu Yanwei Wang Dandan Hao Fuchang Liu Mingju Mitri Hani S. | 2017 | International Journal of Mining Science and Technology2017，27，6： | 8 |
| 13 | Dynamic property tests of frozen red sandstone using a split hopkinson pressure bar显示文摘In this study, frozen red sandstone specimens were impacted by a Split Hopkinson bar (SHPB), with a velocity of 4.558 ~ 6.823 ms-1. The temperature of the specimens was maintained at -15℃ during the experiment. For comparison purposes, static uniaxial compression tests were conducted in advance using a freezing triaxial test machine. Four stress-strain curves were obtained in diff erent average strain rates. The test results suggested that when the average strain rate is low, the specimen strength changes gradually;but when it is high, its strength changes rapidly. When the average strain rate is 120.73 s-1, the peak value of stress is as high as 82.96 MPa, which is about two times that of the static compressive strength of 44.1 MPa. A constitutive model was established that was composed of the damaged, viscoelastic and spring bodies, and revealed the variations of compressive strength and strain for the frozen red sandstone under diff erent high strain rates. The test results also showed that the failure form was correlated to the average strain rate of the frozen red sandstone. When the average strain rate is low, the damage was only distributed on the specimen’s edges. However, as the average strain rate increases, the damage range extended to the central parts of the specimen. When the average strain rate reached 107.34s-1, the specimen was smashed. | Shan Renliang Song Yongwei Song Liwei Bai Yao | 2019 | Earthquake Engineering and Engineering Vibration2019，18，3： | 8 |
| 14 | A modified Johnson–Cook model for 7N01 aluminum alloy under dynamic condition显示文摘Tensile tests at different strain rates(0.0002, 0.002, 0.02, 1000 and 3000 s^(-1)) were carried out for 7N01 aluminum alloy. Low strain rate experiments(0.0002, 0.002 and 0.02 s^(-1)) were conducted using an electronic mechanical universal testing machine, while high strain rate experiments(1000, 3000 s^(-1)) were carried out through a split Hopkinson tensile bar. The experimental results showed that 7N01 aluminum alloy is strain rate sensitive. By introducing a correction scheme of the strain rate hardening coefficient, a modified Johnson–Cook model was proposed to describe the flow behaviors of 7N01 aluminum alloy. The proposed model fitted the experimental data better than the original Johnson–Cook model in plastic flow under dynamic condition. Numerical simulations of the dynamic tensile tests were performed using ABAQUS with the modified Johnson–Cook model. Digital image correlation was used together with high-speed photography to study the mechanical characters of specimen at high strain rate. Good correlations between the experiments results, numerical predictions and DIC results are achieved. High accuracy of the modified Johnson-Cook model was validated. | 张一犇 姚松 洪翔 王中钢 | 2017 | Journal of Central South University2017，24，11： | 7 |
| 15 | Interaction between two sliders in a system with rate- and state-dependent friction显示文摘This study examines slip recurrence patterns in a two-block spring-slider model with rate- and state-dependent friction. Both weak and strong heterogeneities are considered with different settings of coupling stiffness. The results show that the recurrence pattern of slips strongly depends on the degree of coupling between the two blocks. With strong coupling between the two blocks (e.g., kc/ki max >~1), the slip pattern of the system is simple and characterized by periodical stick-slips, with the two blocks slipping together. With strong heterogeneity in friction strength, period-2 motion is found for moderate coupling stiffness (kc/ki max=0.4) between the two blocks. More complicated patterns are found with weak coupling stiffness (kc/ki max=0.2) and strong heterogeneity. With strong heterogeneity, very weak coupling leads to chaotic slip patterns. With coupling stiffness kc=5 ki max and strong heterogeneity, chaotic slip patterns are not found, in contrast with the results by Huang and Turcotte who employed the classical static/kinetic friction law. | HE Changrong (何昌荣) | 2003 | Science China Earth Sciences2003，46，z2： | 7 |
| 16 | A NEW DAMAGE MODEL FOR MICROCRACK-WEAKENED BRITTLE SOLIDS显示文摘In the present paper, a micromechanically based damage model formicrocrack-weakened solids is developed. The concept of the domain of microcrackgrowth (DMG) is defined and used to describe the damage state and the anisotropicproperties of brittle materials. After choosing an appropriate fracture criterion ofmicrocrack, we obtain the analytical expression of DMG under a monotonically in-creasing proportional plane stress. Under a complex loading path, the evolutionequation of DMG and the overall effective compliance tensor of damaged materialsare given. | 冯西桥 余寿文 | 1993 | Acta Mechanica Sinica1993，9，3： | 6 |
| 17 | Dynamic softening behaviors of 7075 aluminum alloy显示文摘The dynamic softening behaviors during hot deformation of 7075 aluminum alloy were studied by isothermal hot compression tested at temperatures of 250, 300, 350, 400 and 450 ℃ and strain rates of 0.01, 0.1, 1 and 10 s-1 on Gleeble1500. The results show that the temperature changes have a significant effect on the dynamic softening rate. It is indicated that the considerable dynamic softening rate associated with dynamic recrystallization leads flow stress value decreasing gradually. A group of coefficients needed by the phenomenological constitutive model containing a softening ratio item were calculated by the multiple linear regression method. The optical microstructures show that the grains of billets compressed become more and more refined with strain rate increasing as well as the degree of dynamic softening and work-hardening higher. The phenomenological constitutive description of 7075 aluminum alloy can accurately describe the relationships among flow stress, temperature, strain rate, strain and dynamic softening, and offer the basic model for plastic forming process simulation. | 权国政 刘克威 周杰 陈斌 | 2009 | 中国有色金属学会会刊:英文版2009，19，S3： | 6 |
| 18 | Thermodynamic watershed hydrological model: Constitutive relationship显示文摘The representative elementary watershed (REW) approach proposed by Reggiani et al. was the first attempt to develop scale adaptable equations applicable directly at the macro scale. Tian et al. extended the initial definition of REW for simulating the energy related processes, and re-organized the deriving procedure of balance equations so that additional sub-regions and substances could be easily incorpo-rated. The resultant ordinary differential equation set can simulate various hydro-logical processes in a physically reasonable way. However, constitutive and geo-metric relationships have not been developed for Tian et al.'s equation set, which are necessary for the thermodynamic watershed hydrological model to apply in hydrological modeling practice. In this work, the constitutive equations for mass exchange terms and momentum exchange terms were developed as well as geo-metric relationships. The closed ordinary differential equation set with nine equa-tions was finally obtained. | TIAN FuQiang HU HePing LEI ZhiDong | 2008 | Science China(Technological Sciences)2008，51，9： | 6 |
| 19 | Refining constitutive relation by integration of finite element simulations and Gleeble experiments显示文摘Thermo-mechanical coupled finite element calculations were carried out to simulate the Gleeble compression of the samples of a titanium alloy(Ti60), and the results are analyzed and compared with the actual compression tests conducted on a Gleeble 3800 thermo-mechanical simulator. The changes in temperature, stress and strain distribution in the samples and the source of error on the constitutive relations from Gleeble hot compression test were analyzed in detail. Both simulations and experiments showed that the temperature distribution in the specimen is not uniform during hot compression, resulting in significant deformation inhomogeneity and non-ignorable error in the flow stress strain relation,invalidating the uniform strain assumption commonly assumed when extracting the constitutive relation from Gleeble tests. Based on the finite element simulations with iterative corrections, we propose a scheme to refine the constitutive relations from Gleeble tests. | D.J. Yu D.S. Xu H. W ang Z.B. Zhao G.Z. Wei R. Yang | 2019 | Journal of Materials Science & Technology2019，35，6： | 6 |
| 20 | Co-regulation of indole glucosinolates and camalexin biosynthesis by CPK5/CPK6 and MPK3/MPK6 signaling pathways^°°显示文摘Secondary plant metabolites,represented by indole glucosinolates(IGS)and camalexin,play important roles in Arabidopsis immunity.Previously,we demonstrated the importance of MPK3 and MPK6,two closely related MAPKs,in regulating Botrytis cinerea(Bc)-induced IGS and camalexin biosynthesis.Here we report that CPK5 and CPK6,two redundant calcium-dependent protein kinases(CPKs),are also involved in regulating the biosynthesis of these secondary metabolites.The loss-of-function of both CPK5 and CPK6 compromises plant resistance to Be.Expression profiling of CPK5-VK transgenic plants,in which a truncated constitutively active CPK5 is driven by a steroidinducible promoter,revealed that biosynthetic genes of both IGS and camalexin pathways are coordinately upregulated after the induction of CPK5-VK,leading to high-level accumulation of camalexin and 4-methoxyindole-3-ylmethylglucosinolate(4MI3G).Induction of camalexin and 4MI3G,as well as the genes in their biosynthesis pathways,is greatly compromised in cpks cpk6 mutant in response to Be.In a conditional cpk5 cpk6 mpk3 mpk6 quadruple mutant,Be resistance and induction of IGS and camalexin are further reduced in comparison to either cpks cpk6 or conditional mpk3 mpk6 double mutant,suggesting that both CPK5/CPK6 and MPK3/MPK6 signaling pathways contribute to promote the biosynthesis of 4MI3G and camalexin in defense against Be. | Liuyi Vang Yan Zhang Rongxia Guan Sen Li Xuwen Xu Shuqun Zhang Juan Xu | 2020 | Journal of Integrative Plant Biology2020，62，11： | 6 |
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