检索结果-南通市图书馆

Acta Mechanica Sinica 2012年第5期28卷 1389-1397页

作者： Amin Manouchehrian Mohammad Fatehi Marji mining and metallurgical engineering department Yazd University

In many situations rocks are subjected to biaxial loading and the failure process is controlled by the lateral confinement stresses. The importance of confinement stresses has been recognized in the literature by many researchers, in particular, its influence on strength and on the angle of fracture, but still there is not a clear description for the influence of confining stress on the crack propagation mechanism of rocks. This paper presents a numerical pro- cedure for the analysis of crack propagation in rock-like ma- terials under compressive biaxial loads. Several numerical simulations of biaxial tests on the rock specimen have been carried out by a bonded particle model （BPM） and the influ- ence of confinement on the mechanism of crack propagation from a single flaw in rock specimens is studied. For this purpose, several biaxial compressive tests on rectangular spec- imens under different confinement stresses were modeled in （2 dimensional particle flow code） PFC2D. The results show that wing cracks initiate perpendicular to the flaw and trend toward the direction of major stress, however, when the lat- eral stresses increase, this initiation angle gets wider. Also it is concluded that in addition to the material type, the initiation direction of the secondary cracks depends on confine- ment stresses, too. Besides, it is understood that secondary cracks may be produced from both tensile and shear mechanisms.

关键词： Crack propagation Confinement Bonded par-ticle model - Rock Secondary cracks

Impact Energy of Functionally Graded Steels with Crack Divider Configuration

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2009年第6期25卷 847-852页

作者： Ali Nazari Jamshid Aghazadeh Mohandesi department of mining and metallurgical engineering Amirkabir University of Technology

Functionally graded steels were produced via electroslag remelting process using the primary electrodes of plain carbon and austenitic stainless steels. Charpy impact energy of as-prepared specimens was measured in the form of crack divider. The obtained results show that the impact energy of the specimens depends on the type and the volume fraction of the present phases. Based on the rule of mixtures, a mathematical model, which correlates the impact energy of functionally graded steels to the impact energy of the individual layers through Vickers microhardness of the layers, was presented. A good compatibility between the experimental results and those obtained from the model was observed.

关键词： Graded steels Impact energy Crack divider Mathematical model

Reliability analysis of production schedule in multi-element deposits under grade-tonnage uncertainty with multi-destinations for the run of mine material

在线全文

学校读者我要写书评

暂无评论

International Journal of mining Science and Technology 2019年第3期29卷 483-489页

作者： Mohsen Jamshidi Morteza Osanloo department of mining and metallurgical engineering Amirkabir University of Technology

Blending contributes to create an opportunity to achieve the target feed material and helps optimize the run of mine(ROM)*** addition,it allows mixing different materials and achieving a wide range of ***,multiple destinations can be considered for *** present study seeks to develop a Mixed Integer Programming(MIP)model for the production scheduling of an iron ore *** on this model,different destinations are considered for mine products with different *** this aim,ten scenarios were considered with a number of different *** results indicated that the maximum NPV in the multiple product scenarios is about 15%more than that of the single product ***,30 realizations were used to evaluate the effect of grade and tonnage *** reliability of the production plan was approximately 61.07%and 62.81%in the first and second period of exploitation,respectively.

关键词： Production Blending Multiple products Reliability Mixed Integer Programming model

Microstructural evolution and mechanical properties of nanostructured Cu-Al-Ni shape memory alloys

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2012年第4期19卷 333-338页

作者： M. Izadinia K. Dehghani mining and metallurgical engineering department Amirkabir University of Technology

The melt spinning technique, with an applied cooling rate of about 106 K/s, was used to produce a nanostructured Cu＋13.2Al＋ 5.1Ni （in wt%） shape memory alloy. The properties of nanostructured ribbons were then compared with those of conventional coarse struc- ture. The microstructural evolution was characterized using scanning electron microscopy （SEM）, atomic force microscopy （AFM） and X-ray diffraction （XRD） techniques. Microhardness measurements indicate a two-fold increase in hardness because of the produced nanos- lructure. Comparing to its coarse structure, the nanostructured Cu-A1-Ni shape memory alloy exhibited the enhanced mechanical properties including a ductility of 6.5% and a pronounced plateau in the stress-strain curve.

关键词： copper allosy shape memory effect melt spinning mechanical properties microstructural evolution

Hot Ductility of Severe Plastic Deformed AA6061 Aluminum Alloy

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2015年第3期28卷 322-330页

作者： Ali Akbar Khamei Kamran Dehghani mining and metallurgical engineering department Amirkabir University of Technology

The hot ductility of 6061 aluminum alloy,which was subjected to two different severe plastic deformations（SPD）,was studied at different temperatures and strain *** tensile tests were carried out at the temperature range of 300-500 ℃ and at the strain rates of 0.0005-0.01 s^（-1）.The microstructure evolution was characterized using optical microscopy,transmission electron microscopy and X-ray diffraction *** influences of the microstructure after SPD,thermomechanical parameters（temperature and strain rate） and specimen size on the hot formability of this alloy were then *** results show that a decrease in grains/subgrains exhibited significant effect on the hot ductility of SPDed *** constitutive equations were then developed to model the hot formability of the studied *** developed model can be represented by Zener-Hollomon parameter in a hyperbolic sinusoidal equation *** the changes of elongation to failure and Zener-Hollomon parameter indicate that the hot ductility of the alloy is more sensitive to the temperature rather than to the strain *** uniform elongation is independent of the specimen size,but the postnecking elongation increases dramatically as the ratio of l/A^（1/2） decreases.

关键词： Al-Mg-Si alloy Deformation behavior Equal channel angular pressing(ECAP) Rolling Hot tensile deformation

A method for extracting anomaly map of Au and As using combination of U-statistic and Euclidean distance methods in Susanvar district,Iran

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2017年第11期24卷 2693-2704页

作者： Seyyed Saeed Ghannadpour Ardeshir Hezarkhani Mostafa Sharifzadeh department of mining & metallurgical engineering Amirkabir University of Technology (Tehran Polytechnic) department of mining engineering and metallurgical engineering Western Australia School of MineCurtin University

Quantitative descriptions of geochemical patterns and providing geochemical anomaly map are important in applied geochemistry. Several statistical methodologies are presented in order to identify and separate geochemical anomalies. The U-statistic method is one of the most important structural methods and is a kind of weighted mean that surrounding points of samples are considered in U value determination. However, it is able to separate the different anomalies based on only one variable. The main aim of the presented study is development of this method in a multivariate mode. For this purpose, U-statistic method should be combined with a multivariate method which devotes a new value to each sample based on several variables. Therefore, at the first step, the optimum p is calculated in p-norm distance and then U-statistic method is applied on p-norm distance values of the samples because p-norm distance is calculated based on several variables. This method is a combination of efficient U-statistic method and p-norm distance and is used for the first time in this research. Results show that p-norm distance of p=2(Euclidean distance) in the case of a fact that Au and As can be considered optimized p-norm distance with the lowest error. The samples indicated by the combination of these methods as anomalous are more regular, less dispersed and more accurate than using just the U-statistic or other nonstructural methods such as Mahalanobis distance. Also it was observed that the combination results are closely associated with the defined Au ore indication within the studied area. Finally, univariate and bivariate geochemical anomaly maps are provided for Au and As, which have been respectively prepared using U-statistic and its combination with Euclidean distance method.

关键词： mineral anomaly Susanvar district U-statistic method Euclidean distance bivariate anomaly map

Comparing the Fatigue and Corrosion Behavior of Nanograin and Coarse-Grain IF Steels

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2015年第3期28卷 295-301页

作者： A.Chabok K.Dehghani M.Ahmadi Jazani mining and metallurgical engineering department Amirkabir University of Technology

In the present work,a nanograin layer of about 150 μm thick was formed on the surface of an interstitial-free（IF） steel via friction stir ***,the fatigue and corrosion behaviors of IF steel with nanograin layer were compared with that of coarse-structure *** than threefold increase in the hardness was observed due to the formation of nanograin *** size of nanograms in the stir zone was within 30-150 *** resulted in 50%increase in the fatigue strength of nanostructured ***,the fracture surfaces were characterized using field emission scanning electron microscopy and scanning electron *** for the fatigue behavior of nanograin IF steel,the fracture surface was characterized by the formation of nanospacing striations and ***,the nanograin structure pronounced the passivity and exhibited higher corrosion resistance.

关键词： Nanograin Interstitial-free(IF) steel Fatigue Friction stir processing(FSP) Corrosion

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2018年第11期31卷 1183-1196页

作者： Farhad Bakhtiari Argesi Ali Shamsipur Seyyed Ehsan Mirsalehi department of mining and metallurgical engineering Amirkabir University of Technology

In this study, the dissimilar friction stir welding （FSW） butt joints between aluminum alloy 5754-H114 and commerciallypure copper were investigated. The thickness of welded plates was 4 mm and the aluminum plate was placed on theadvancing side. In order to obtain a suitable flow and a better material mixing, a 1-mm offset was considered for thealuminum plate, toward the butt centerline. For investigating the microstructure and mechanical properties of FSWedjoints, optical microscopy and mechanical tests （i.e., uniaxial tensile test and microhardness） were used, ***, the analysis of intermetallic compounds and fracture surface was examined by scanning electron microscopyand X-ray diffraction. The effect of heat generation on the mechanical properties and microstructure of the FSWed jointswas investigated. The results showed that there is an optimum amount of heat input. The intermetallic compounds formedin FSWed joints were A14Cu9 and AI2Cu. The best results were found in joints with 1000 rpm rotational speed and100 mm/min travel speed. The tensile strength was found as 219 MPa, which reached 84% of the aluminum base ***, maximum value of the microhardness of the stir zone （SZ） was attained as about 120 HV, which was greatlydepended on the grain size, intermetallic compounds and copper pieces in SZ.

关键词： Friction stir welding 5754-H114 aluminum alloy Pure copper Heat generation Microstructure Intermetallic compounds

Application of artificial neural networks to the prediction of tunnel boring machine penetration rate

在线全文

学校读者我要写书评

暂无评论

mining Science and Technology 2010年第5期20卷 727-733页

作者： JAVAD Gholamnejad NARGES Tayarani department of mining and metallurgical engineering Yazd University mining & metallurgical engineering Yazd University

Rate of penetration of a Tunnel Boring Machine(TBM) in a rock environment is generally a key parameter for the successful accomplishment of a tunneling *** paper presents the results of a study into the application of an Artificial Neural Network(ANN) technique for modeling the penetration rate of tunnel boring machines.A database,including actual,measured TBM penetration rates,uniaxial compressive strengths of the rock,the distance between planes of weakness in the rock mass and rock quality designation was *** collected from three different TBM projects(the Queens Water Tunnel,USA,the Karaj-Tehran water transfer tunnel,Iran,and the Gilgel Gibe II hydroelectric project,Ethiopia).A five-layer ANN was found to be optimum,with an architecture of three neurons in the input layer,9,7 and 3 neurons in the first,second and third hidden layers,respectively,and one neuron in the output *** correlation coefficient determined for penetration rate predicted by the ANN was 0.94.

关键词： artificial neural networks TBM tunneling penetration rate modeling

Machine Learning Techniques in Predicting Hot Deformation Behavior of Metallic Materials

在线全文

学校读者我要写书评

暂无评论

Computer Modeling in engineering & Sciences 2025年第1期142卷 713-732页

作者： Petr Opela Josef Walek Jaromír Kopecek department of metallurgical Technologies Faculty of Materials Science and TechnologyVSB–Technical University of OstravaOstrava70800Czech Republic FZU—Institute of Physics of the Czech Academy of Sciences Prague18200Czech Republic

In engineering practice,it is often necessary to determine functional relationships between dependent and independent *** relationships can be highly nonlinear,and classical regression approaches cannot always provide sufficiently reliable ***,Machine Learning(ML)techniques,which offer advanced regression tools to address complicated engineering issues,have been developed and widely *** study investigates the selected ML techniques to evaluate their suitability for application in the hot deformation behavior of metallic *** ML-based regression methods of Artificial Neural Networks(ANNs),Support Vector Machine(SVM),Decision Tree Regression(DTR),and Gaussian Process Regression(GPR)are applied to mathematically describe hot flow stress curve datasets acquired experimentally for a medium-carbon *** the GPR method has not been used for such a regression task before,the results showed that its performance is the most favorable and practically unrivaled;neither the ANN method nor the other studied ML techniques provide such precise results of the solved regression analysis.

关键词： Machine learning Gaussian process regression artificial neural networks support vector machine hot deformation behavior