检索结果-南通市图书馆

size effectS OF ELASTIC MODULUS OF FCC METALS BASED ON THE CAUCHY-BORN RULE AND NANOPLATE MODELS

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2014年第2期27卷 111-121页

作者： Jianyun Liu Jingru Song Yueguang Wei State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences

In the present research, a simple quasi-continuum model, the Cauchy-Born rule model, is used to investigate the size effects of elastic modulus for fcc metals. By considering a nanoplate model and calculating the strain energy for the nano-sized plate under tension and bending, the relationship between the elastic modulus and the plate thickness is found. size effects of the elastic modulus are displayed by the relative differences of the elastic modulus between the nano-sized plate sample and the bulk sample. By comparing the present results with those of others, the effectiveness of the Cauchy-Born rule model in studying the size effects of material properties are shown.

关键词： quasi-continuum method Cauchy-Born rule size effect elastic modulus fcc-metal

size effects in the uniaxial compressive properties of 3D printed models of rocks:an experimental investigation

在线全文

学校读者我要写书评

暂无评论

International Journal of Coal Science & Technology 2022年第6期9卷 1-12页

作者： Hao Wu Yang Ju Xin Han Zhangyu Ren Yue Sun Yanlong Zhang Tianyi Han School of Mechanics&Civil Engineering China University of Mining&Technology(Beijing)Beijing 100083China State Key Laboratory of Coal Resources and Safe Mining China University of Mining&Technology(Beijing)Beijing 100083China School of Emergency Management and Safety Engineering China University of Mining&Technology(Beijing)Beijing 100083China

Transparent physical models of real rocks fabricated using three-dimensional(3D)printing technology are used in photoelas-tic experiments to quantify the evolution of the internal stress and deformation fields of ***,they are rendered as an emerging powerful technique to quantitatively reveal the intrinsic mechanisms of rock *** mechanical behav-ior of natural rocks exhibits a significant size effect;however,limited research has been conducted on whether transparent physical models observe similar size *** this study,to make the transparent printed models accurately demonstrate the mechanical behavior of natural rocks and reveal the internal mechanism of the size effect in rock mechanical behavior,the size effect in 3D printed models of fractured and porous rocks under uniaxial compressive loading was *** cylindrical models with different sizes that contained different fractured and porous structures were printed using the fracture and porous characteristics extracted from natural coal and *** variation in uniaxial compres-sive strength and elastic modulus of fractured and porous models for increasing model sizes were obtained through uniaxial compression ***,the influence of internal discontinuous structural features,such as fractures and pores,on the size effect pertaining to the mechanical behavior of the model was analyzed and elaborated by comparing it with the mechanical properties of the continuous homogeneous model without fractures and *** findings provided support and reference to analyze the size effect of rock mechanical behavior and the effect of the internal discontinuous structure using 3D printed transparent models.

关键词： size effect 3D printed model Rocks Mechanical property Fractures Pores

size effects on the tensile strength and fracture toughness of granitic rock in different tests

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2023年第9期15卷 2179-2192页

作者： Ignacio Pérez-Rey Andrea Muñoz-Ibáñez Manuel A.González-Fernández Mauro Muñiz-Menéndez Miguel Herbón Penabad Xian Estévez-Ventosa Jordi Delgado Leandro RAlejano Laboratorio de Geotecnia CEDEXMadridSpain CINTECX GESSMin GroupDepartment of Natural Resources and Environmental EngineeringUniversidade de VigoVigoSpain School of Civil Engineering Universidade da CoruñaA CoruñaSpain

This study investigates the tensile failure mechanisms in granitic rock samples at different scales by means of different types of *** do that,we have selected a granitic rock type and obtained samples of different sizes with the diameter ranging from 30 mm to 84 *** samples have been subjected to direct tensile strength(DTS)tests,indirect Brazilian tensile strength(BTS)tests and to two fracture toughness testing *** DTS and fracture toughness were found to consistently grow with sample size,this trend was not clearly identified for BTS,where after an initial grow,a plateau of results was *** is a rather complete database of tensile related properties of a single rock *** if similar databases are rare,the obtained trends are generally consistent with previous scatter and partial experimental ***,different observations apply to different types of rocks and experimental *** differences in variability and mean values of the measured parameters at different scales are critically analysed based on the heterogeneity,granular structure and fracture mechanics *** potential relations between parameters are revised and an indication is given on potential sample sizes for obtaining reliable *** this database with different types of rocks is thought to be convenient to advance towards a better understanding of the tensile strength of rock materials.

关键词： size effect Tensile strength Fracture toughness Granite Finite fracture mechanics

Synergistic effect of size-dependent PtZn nanoparticles and zinc single-atom sites for electrochemical ozone production in neutral media

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2020年第12期29卷 312-322页

作者： Bowen Yuan Zihao Yao Chenlong Qiu Haiyang Zheng Yilong Yan Qiaoqiao Zhang Xiang Sun Yu Gu Xing Zhong Jianguo Wang Institute of Industrial Catalysis State Key Laboratory Breeding Base of Green-Chemical Synthesis TechnologyCollege of Chemical EngineeringZhejiang University of TechnologyHangzhou 310032ZhejiangChina

Electrochemical ozone production(EOP) via water electrolysis represents an attractive method for the generation of high-purity O3. Herein, the X-PtZn/Zn-N-C electrocatalysts show a strong structural sensitive behavior depends on the size of the PtZn nanoparticles and their EOP activity exhibits a volcano-type dependence for the O3 performance in neutral media. The 7.7-PtZn/Zn-N-C exhibits EOP current efficiency of 4.2%, and shows the prominent performance in the production of gaseous O3 with a value of 1647 ppb at 30 min, which is almost 4-fold compared to 2.2-Pt Zn/Zn-N-C. Based on the experiments and theoretical calculations, the performance of the EOP process was determined by the nanoparticle size-effect and the synergistic effect between the PtZn nanoparticles and atomically dispersed Zn-N-C. Furthermore, the fivemembered cyclic structure of O3 can be stabilized between the PtZn nanoparticle and the Zn-N-C support,indicating that O3 is produced at the interface.

关键词： Electrochemical ozone production PtZn Single-atom catalysts size effect Synergistic effect

PARTICULATE size effectS IN THE PARTICLE-REINFORCED METAL-MATRIX COMPOSITES

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2001年第1期17卷 45-58页

作者：魏悦广 LNM Institute of Mechanics Chinese Academy of Sciences Beijing China 100080

The influences of I,article size on the mechanical properties of the particulate metal matrix composite;are obviously displayed in the experimental observations. However, the phenomenon can not be predicted directly using the conventional elastic-plastic theory. It is because that no length scale parameters are involved in the conventional theory. In the present research, using the strain gradient plasticity theory, a systematic research of the particle size effect in the particulate metal matrix composite is carried out. The roles of many composite factors, such as: the particle size, the Young's modulus of the particle, the particle aspect ratio and volume fraction, as well as the plastic strain hardening exponent of the matrix material, are studied in detail. In order to obtain a general understanding for the composite behavior, two kinds of particle shapes, ellipsoid and cylinder, are considered to check the strength dependence of the smooth or non-smooth particle surface. Finally, the prediction results will be applied to the several experiments about the ceramic particle-reinforced metal-matrix composites. The material length scale parameter is predicted.

关键词： size effect strain gradient plasticity the particle-reinforced metal-matrix composite

effect of size on mechanical behavior of Au pillars by molecular dynamics study

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2012年第6期55卷 1111-1117页

作者： TANG QiHeng State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

The influence of specimen size on the mechanical behavior of Au pillars is studied by means of molecular dynamics (MD) simulations with the EAM *** compression at 300 K,as the deformation of pillars is in the plastic stage,nucleation of partial dislocations is *** coupling effect of surface stress and thermal activation is considered when analyzing the size effect on the yield property of the Au *** appears that both the tensile stress component and the temperature in the surface layer impart significant effect on the mechanical behaviors of the nano-sized Au pillars.

关键词： molecular dynamics simulation size effect dislocation compression

The size effects on Process Design of Micro Deep Drawing

在线全文

学校读者我要写书评

暂无评论

Journal of Shanghai Jiaotong university(Science) 2007年第3期12卷 323-327页

作者：马宁董湘怀 Dept. of Plasticity Technology Shanghai Jiaotong Univ.

This paper suggested to reformulate cylindrical deep drawing parameters with dimensionless form. A diagram, in which a feasible zone is drawn to bound both the maximal allowable tension and compression stress during the deep drawing process, was established. Since it is presented in a dimensionless form, it may be applied for both conventional and micro deep drawing. Cylindrical cup deep drawing was taken as an example to show the dimensionless process design method. In addition, the size effects should be taken into account. Two kinds of size effects on micro deep drawing were investigated, which can be explained by surface layer model and strain gradient model. Numerical simulations were carried out to compare the strain distribution with or without consideration of size effect.

关键词： micro deep drawing size effect surface layer strain gradient

Numerical Investigation of the Cushion and size effects During Single-Particle Crushing via DEM

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2020年第6期33卷 851-863页

作者： Du-min Kuang Zhi-lin Long Rui-qi Guo Piao-yi Yu Xu-tong Zhou Jie Wang College of Civil Engineering and Mechanics Xiangtan UniversityXiangtan 411105China

This paper uses the discrete element method to model the size and cushion effects during single-particle crushing *** propose simplified numerical modeling to examine the effects of particle size and coordination number on particle breakage *** validate the proposed modeling by comparing the numerical results with the experimental data reported in the literature,in terms of the variability of particle tensile strength and axial force-displacement *** on the numerical results,it is clear that a larger particle size entails a higher tensile strength with a larger *** addition,the characteristic tensile strength increases linearly with an increasing coordination ***,smaller particles are more susceptible to the cushion effect than larger *** numerical results also indicate that an increasing coordination number induces a more ductile mode of *** on these results,we propose an empirical equation for calculating tensile strength,incorporating both the cushion effect and the size effect.

关键词： Particle breakage Cushion effect size effect Discrete element method

Multi-dimensional size effects and representative elements for nonpersistent fractured rock masses: A perspective of geometric parameter distribution

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2023年第9期15卷 2339-2354页

作者： Jia Wang Wen Zhang Chun Tan Zhenbang Nie Wenliang Ma Donghui Chen Qi Sun College of Construction Engineering Jilin UniversityChangchun130026China China Water Northeastern Investigation Design and Research Co.Ltd.Changchun130026China North China Power Engineering Co. Ltd.of China Power Engineering Consulting GroupChangchun130000China

This study takes a fractured rock mass in the Datengxia Hydropower Station,China as an example to analyze the size effects and determine the representative elementary sizes.A novel method considering geometric parameter distributions is proposed in this *** proposed method can quickly and simply determine the size effects and representative elementary ***,geometric parameter distributions,including fracture frequency,size and orientation,are generated on the basis of the Bernoulli trial and Monte Carlo *** distributions are assessed using the coefficient of variation(CV),and the acceptable variations for CV(5%,10%and 20%)are used to determine representative elementary ***,the representative element of rock masses is the representative elementary volume(REV).The present study extends the representative element to other dimensions,*** elementary length(REL)and representative elementary area(REA)for one and two dimensions,*** and REA are useful in studying the size effects of one-(1D)and twodimensional(2D)characteristics of rock *** relationships among multi-dimensional representative elementary sizes are *** representative elementary sizes reduce with the increase in the dimensions,and REA and REV can be deduced by ***,the proposed method can quickly and simply determine REL and further estimate REA and REV,which considerably improves the efficiency of rock mass analysis.

关键词： size effect Discrete fracture network(DFN) Stochastic mathematics Anisotropy Coefficient of variation(CV)