Subjects -> METALLURGY (Total: 59 journals)
Showing 1 - 10 of 10 Journals sorted alphabetically
Acta Metallurgica Slovaca     Open Access   (Followers: 2)
Advanced Device Materials     Open Access   (Followers: 6)
American Journal of Fluid Dynamics     Open Access   (Followers: 51)
Archives of Metallurgy and Materials     Open Access   (Followers: 9)
Asian Journal of Materials Science     Open Access   (Followers: 5)
Canadian Metallurgical Quarterly     Hybrid Journal   (Followers: 21)
Complex Metals     Open Access   (Followers: 2)
Corrosion Communications     Open Access   (Followers: 1)
Energy Materials : Materials Science and Engineering for Energy Systems     Hybrid Journal   (Followers: 24)
Handbook of Magnetic Materials     Full-text available via subscription   (Followers: 2)
High Temperature Materials and Processes     Open Access   (Followers: 6)
Indian Journal of Engineering and Materials Sciences (IJEMS)     Open Access   (Followers: 11)
International Journal of Metallurgy and Alloys     Full-text available via subscription   (Followers: 3)
International Journal of Metals     Open Access   (Followers: 7)
International Journal of Minerals, Metallurgy, and Materials     Hybrid Journal   (Followers: 13)
International Journal of Mining and Geo-Engineering     Open Access   (Followers: 4)
Ironmaking & Steelmaking     Hybrid Journal   (Followers: 5)
ISIJ International - Iron and Steel Institute of Japan     Full-text available via subscription   (Followers: 26)
Izvestiya Vuzov. Poroshkovaya Metallurgiya i Funktsional’nye Pokrytiya (Proceedings of Higher Schools. Powder Metallurgy аnd Functional Coatings)     Full-text available via subscription   (Followers: 2)
JOM Journal of the Minerals, Metals and Materials Society     Hybrid Journal   (Followers: 36)
Journal of Advanced Joining Processes     Open Access  
Journal of Central South University     Hybrid Journal   (Followers: 1)
Journal of Cluster Science     Hybrid Journal  
Journal of Heavy Metal Toxicity and Diseases     Open Access  
Journal of Iron and Steel Research International     Hybrid Journal   (Followers: 11)
Journal of Materials & Metallurgical Engineering     Full-text available via subscription   (Followers: 2)
Journal of Materials Processing Technology     Hybrid Journal   (Followers: 21)
Journal of Metallurgical Engineering     Open Access   (Followers: 4)
Journal of Sustainable Metallurgy     Hybrid Journal   (Followers: 3)
Materials Science and Metallurgy Engineering     Open Access   (Followers: 7)
Metallurgical and Materials Engineering     Open Access   (Followers: 7)
Metallurgical and Materials Transactions A     Hybrid Journal   (Followers: 43)
Metallurgical and Materials Transactions B     Hybrid Journal   (Followers: 33)
Metallurgical and Materials Transactions E     Full-text available via subscription   (Followers: 2)
Metallurgical Research & Technology     Full-text available via subscription  
Metallurgical Research and Technology     Full-text available via subscription   (Followers: 8)
Metallurgy and Foundry Engineering     Open Access   (Followers: 3)
Mining, Metallurgy & Exploration     Hybrid Journal  
Powder Diffraction     Full-text available via subscription   (Followers: 1)
Powder Metallurgy     Hybrid Journal   (Followers: 35)
Powder Metallurgy and Metal Ceramics     Hybrid Journal   (Followers: 7)
Powder Metallurgy Progress     Open Access   (Followers: 5)
Practical Metallography     Full-text available via subscription   (Followers: 5)
Rare Metals     Hybrid Journal   (Followers: 3)
Revista de Metalurgia     Open Access  
Revista del Instituto de Investigación de la Facultad de Ingeniería Geológica, Minera, Metalurgica y Geográfica     Open Access  
Revista Remetallica     Open Access   (Followers: 1)
Russian Metallurgy (Metally)     Full-text available via subscription   (Followers: 4)
Science and Technology of Welding and Joining     Hybrid Journal   (Followers: 8)
Soldering & Surface Mount Technology     Hybrid Journal   (Followers: 2)
Stainless Steel World     Full-text available via subscription   (Followers: 17)
Transactions of the IMF     Hybrid Journal   (Followers: 14)
Transactions of the Indian Institute of Metals     Hybrid Journal   (Followers: 5)
Tungsten     Hybrid Journal  
Universal Journal of Materials Science     Open Access   (Followers: 3)
Welding in the World     Hybrid Journal   (Followers: 8)
Welding International     Hybrid Journal   (Followers: 11)
Вісник Приазовського Державного Технічного Університету. Серія: Технічні науки     Open Access  
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Journal of Central South University
Journal Prestige (SJR): 0.336
Citation Impact (citeScore): 1
Number of Followers: 1  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 2095-2899 - ISSN (Online) 2227-5223
Published by Springer-Verlag Homepage  [2654 journals]
  • Mechanical behavior of deep sandstone under high stress-seepage coupling

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      Abstract: Abstract The mechanical behavior evolution characteristics of sandstone are important to the application and practice of rock engineering. Therefore, a new method and concept of deep rock mechanics testing are proposed to reveal the mechanical behavior evolution mechanism of deep roadway surrounding rock after excavation with a depth over 1000 m. High stress-seepage coupling experiments of deep sandstone under various confining pressures are conducted using GCTS. Stress — strain and permeability curves are obtained. The three-stage mechanical behavior of deep sandstone is better characterized. A platform and secondary compaction phenomena are observed. With the confining pressure increasing, the platform length gradually decreases, even disappears. In the stade I, the rigid effect of deep sandstone is remarkable. In the stage II, radial deformation of deep sandstone dominates. The transient strain of confining pressure compliance is defined, which shows three-stage evolution characteristics. In the stage III, the radial deformation is greater than the axial deformation in the pre-peak stage, but the opposite trend is observed in the post-peak stage. It is found that the dynamic permeability can be more accurately characterized by the radial strain. The relations between the permeability and stress-strain curves in various stages are revealed.
      PubDate: 2021-09-16
      DOI: 10.1007/s11771-021-4791-x
       
  • Heat strain in chemical protective clothing in hot-humid environment:
           Effects of clothing thermal properties

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      Abstract: Abstract Heat strain experienced by individuals wearing chemical protective clothing (CPC) is severe and dangerous especially in hot-humid environment. The development of material science and interdisciplinary studies including ergonomics, physiology and heat transfer is urgently required for the reduction of heat strain. The aim of this paper was to study the relationship among clothing thermal properties, physiological responses and environmental conditions. Three kinds of CPC were selected. Eight participants wore CPC and walked (4 km/h, two slopes with 5% and 10%) on a treadmill in an environment with (35±0.5) °C and RH of (60±5)%. Core temperature, mean skin temperature, heart rate, heat storage and tolerance time were recorded and analyzed. Physiological responses were significantly affected by the clothing thermal properties and activity intensity in hot-humid environment. The obtained results can help further development of heat strain model. New materials with lower evaporative resistance and less weight are necessary to release the heat strain in hot-humid environments.
      PubDate: 2021-09-06
      DOI: 10.1007/s11771-021-4670-5
       
  • Influence of brittleness and confining stress on rock cuttability based on
           rock indentation tests

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      Abstract: Abstract In order to understand the influence of brittleness and confining stress on rock cuttability, the indentation tests were carried out by a conical pick on the four types of rocks. Then, the experimental results were utilized to take regression analysis. The eight sets of normalized regression models were established for reflecting the relationships of peak indentation force (PIF) and specific energy (SE) with brittleness index and uniaxial confining stress. The regression analyses present that these regression models have good prediction performance. The regressive results indicate that brittleness indices and uniaxial confining stress conditions have non-linear effects on the rock cuttability that is determined by PIF and SE. Finally, the multilayer perceptual neural network was used to measure the importance weights of brittleness index and uniaxial confining stress upon the influence for rock cuttability. The results indicate that the uniaxial confining stress is more significant than brittleness index for influencing the rock cuttability.
      PubDate: 2021-09-04
      DOI: 10.1007/s11771-021-4766-y
       
  • Mechanical properties and microstructure evolution of an Al-Cu-Li alloy
           subjected to rolling and aging

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      Abstract: Abstract The mechanical properties and microstructure of Al-Cu-Li alloy sheets subjected to cryorolling (−100 °C, −190 °C) or hot rolling (400 °C) and subsequent aging at 160 °C for different times were investigated. The dynamic precipitation and dislocation characterizations were examined via transmission electron microscopy and X-ray diffraction. The grain morphologies and the fracture-surface morphologies were studied via optical microscopy and scanning electron microscopy. Samples subjected to cryorolling followed by aging exhibited relatively high dislocation densities and a large number of precipitates compared with hot-rolled samples. The samples cryorolled at −190 °C and then aged for 15 h presented the highest ultimate tensile strength (586 MPa), while the alloy processed via hot rolling followed by 10 h aging exhibited the highest uniform elongation rate (11.5%). The size of precipitates increased with the aging time, which has significant effects on the interaction mechanism between dislocations and precipitates. Bowing is the main interaction method between the deformation-induced dislocations and coarsened precipitates during tensile tests, leading to the decline of the mechanical properties of the alloy during overaging. These interesting findings can provide significant insights into the development of materials possessing both excellent strength and high ductility.
      PubDate: 2021-08-10
      DOI: 10.1007/s11771-021-4764-0
       
  • Synthesis of nano- to micrometer-sized B4C particle-reinforced aluminum
           matrix composites via powder metallurgy and subsequent heat treatment

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      Abstract: Abstract B4C/6061Al composites reinforced with nano- to micrometer-sized B4C particles were fabricated via powder metallurgy route consisting of spark plasma sintering (SPS) and hot extrusion and rolling (HER), followed by T6 treatment. The microstructural evolution and mechanical properties were investigated. Results showed that the status of B4C particles changed from a network after SPS to a dispersion distribution after HER. The substructured grains reached 66.5% owing to the pinning effect of nano-sized B4C, and the grain size was refined from 3.12 μm to 1.56 μm after HER. After T6 treatment, dispersed Mg2Si precipitated phases formed, and the grain size increased to 1.87 μm. Fine recrystallized grains around micro-sized B4C were smaller than those in the areas with uniform distribution of nano-sized B4C and Mg2Si. The stress distributions of as-rolled and heated composites were similar, considering that the T6 heat treatment was only effective in eliminating the first internal stress. The Vickers, microhardness, and tensile strength of as-SPSed composites were greatly improved from HV 55.45, 0.86 GPa, and 180 MPa to HV 77.51, 1.08 GPa, and 310 MPa, respectively. Despite the precipitation strengthening, the corresponding values of as-heated composites decreased to HV 70.82, 0.85 GPa, and 230 MPa owing to grain coarsening.
      PubDate: 2021-08-01
      DOI: 10.1007/s11771-021-4770-2
       
  • Lubrication characteristics of external return spherical hinge pair of
           axial piston pump or motor under combined action of inclination and offset
           distance

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      Abstract: Abstract External return mechanism is a mechanical structure applied to axial piston pumps. To study its lubrication characteristics, the Reynolds equation applied to an external return spherical hinge pair was deduced based on the vector equation of relative-motion velocity of the external return spherical hinge pair under the influence of external swash plate inclination and offset distance. The results show that the total friction, axial leakage flow, and maximum value of the maximum oil-film pressure increase with increasing pump-shaft speed and decrease with increasing offset distance in one working cycle when the external-swash-plate inclination is constant. However, the varying offset distance has little effect on the axial leakage flow. The maximum value of the maximum oil-film pressure decreases with increasing external-swash-plate inclination and the total leakage flow increases with increasing external-swash-plate inclination in one working cycle when the offset distance is constant. It can be seen that the abovementioned parameters are important factors that affect the lubrication characteristics of external return spherical hinge pairs. Therefore, the complex effects of different coupling parameters should be comprehensively considered in the design of the external return mechanism.
      PubDate: 2021-08-01
      DOI: 10.1007/s11771-021-4776-9
       
  • Risk assessment of floor water inrush in coal mines based on MFIM-TOPSIS
           variable weight model

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      Abstract: Abstract Floor water inrush is one of the main types of coal mine water hazards. With the development of deep mining, the prediction and evaluation of floor water inrush is particularly significant. This paper proposes a variable weight model, which combines a multi-factor interaction matrix (MFIM) and the technique for order performance by similarity to ideal solution (TOPSIS) to implement the risk assessment of floor water inrush in coal mines. Based on the MFIM, the interaction between seven evaluation indices, including the confined water pressure, water supply condition and aquifer water yield property, floor aquifuge thickness, fault water transmitting ability, fracture development degree, mining depth and thickness and their influence on floor water inrush were considered. After calculating the constant weights, the active degree evaluation was used to assign a variable weight to the indices. The values of the middle layer and final risk level were obtained by TOPSIS. The presented model was successfully applied in the 9901 working face in the Taoyang Mine and four additional coal mines and the results were highly consistent with the engineering situations. Compared with the existing nonlinear evaluation methods, the proposed model had advantages in terms of the weighting, principle explanation, and algorithm structure.
      PubDate: 2021-08-01
      DOI: 10.1007/s11771-021-4775-x
       
  • Experimental investigation on basic law of rock directional fracturing
           with static expansive agent controlled by dense linear multi boreholes

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      Abstract: Abstract Directional rupture is one of the difficult problems in deep rock mechanics and engineering. A directional fracturing method with static expansive agent controlled by dense linear multi boreholes is proposed. A physical experiment is designed and performed to investigate the basic laws of this method. The fracture initiation and propagation process, and the mechanism of directional fracturing are analyzed. The results indicate that a directional fracture is formed along the direction of boreholes layout through directionally fracturing with static expansive agents controlled by the dense linear multi boreholes. According to the variation of strain and the distribution of associated acoustic emission (AE) events and energy, the experiment can be divided into three stages. In the first stage, the static expansive agent expand slowly with no fracturing inside the rock. In the second stage, some initial micro-fracturing occurs inside the rock. In the third stage, a wide range of fracturing occurs inside the sample. The internal micro-fracturing planes are connected to form a macro-fracture. Finally, it propagates to the surface of the sample. The directional fracturing plane presents a relatively smooth plane with little bias but much local fluctuation.
      PubDate: 2021-08-01
      DOI: 10.1007/s11771-021-4782-y
       
  • Application of signal processing and support vector machine to transverse
           cracking detection in asphalt pavement

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      Abstract: Abstract Vibration-based pavement condition (roughness and obvious anomalies) monitoring has been expanding in road engineering. However, the indistinctive transverse cracking has hardly been considered. Therefore, a vehicle-based novel method is proposed for detecting the transverse cracking through signal processing techniques and support vector machine (SVM). The vibration signals of the car traveling on the transverse-cracked and the crack-free sections were subjected to signal processing in time domain, frequency domain and wavelet domain, aiming to find indices that can discriminate vibration signal between the cracked and uncracked section. These indices were used to form 8 SVM models. The model with the highest accuracy and F1-measure was preferred, consisting of features including vehicle speed, range, relative standard deviation, maximum Fourier coefficient, and wavelet coefficient. Therefore, a crack and crack-free classifier was developed. Then its feasibility was investigated by 2292 pavement sections. The detection accuracy and F1-measure are 97.25% and 85.25%, respectively. The cracking detection approach proposed in this paper and the smartphone-based detection method for IRI and other distress may form a comprehensive pavement condition survey system.
      PubDate: 2021-08-01
      DOI: 10.1007/s11771-021-4779-6
       
  • Evolution of anisotropy during sandstone rockburst process under
           double-faces unloading

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      Abstract: Abstract Rockburst is one of the major disasters in deep underground rock mechanics and engineering. The precursors of rockbursts play important roles in rockburst prediction. Strainburst experiments were performed under double-face unloading on sandstone with horizontal bedding planes using an independently designed rockburst testing facility. P-wave propagation time during the tests was automatically recorded by the acoustic emission apparatus. The P-wave velocities were calculated in both two directions to analyze their patterns. To find a characteristic precursor for rockburst, the dynamic evolution of rock anisotropy during the rockburst test is quantified by the anisotropic coefficient k, defined as the ratio of the two P-wave velocities in the directions vertical to and parallel to the bedding planes. The results show that rockburst occurs on the two free surfaces asynchronously. The rockburst failure occurs in the following order: crack generation, rock peeling, particle ejection, and rock fracture. In the process of rockburst under double-face unloading, the potential evolution characteristics of anisotropy can be generalized as anisotropy-isotropy-anisotropy. The suddenly unloading induces damage in the rock and presents anisotropic coefficient k steeply increasing departing from one, i.e., isotropy. The rocks with horizontal bedding planes will reach the isotropic state before rockburst, which could be considered as a characteristic precursor of this kind of rockburst.
      PubDate: 2021-08-01
      DOI: 10.1007/s11771-021-4780-0
       
  • Analysis model for deformation mechanism of strip foundation of building:
           Considering shear effect of down-crossing tunnel under excavation

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      Abstract: Abstract When the tunnel underpasses through the building, it will cause deformation and even damage to the buildings above, and the deformation of building foundation is the key to building safety. Based on the engineering case, the theoretical analysis was employed to evaluate the influence of shield tunnel underpass construction on the stability of the building, and the optimal tunneling parameters in the field construction have been obtained through the verified theoretical model and parameter analysis. First, the strip foundation of the building was simplified to the Timoshenko beam, which was taken into account the shear effect, and then the deformation displacement of the soil at the same place of strip foundation was applied to the simplified Timoshenko beam. Finally, the numerical solution of the displacement of the strip foundation was obtained by using the finite element method and verified its reliability using Euler-Bernoulli beam theoretical model, field monitoring data, and numerical simulation. Parameters analysis for the deformation and internal force of strip foundation under different types of shield machine tunneling parameters showed that the influence of the pressure of shield excavation chamber, thrust of shield, and driving speed played an important role in the deformation of the building’s strip foundation and internal force.
      PubDate: 2021-08-01
      DOI: 10.1007/s11771-021-4786-7
       
  • Application of SVM and PCA-CS algorithms for prediction of strip crown in
           hot strip rolling

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      Abstract: Abstract To make up the poor quality defects of traditional control methods and meet the growing requirements of accuracy for strip crown, an optimized model based on support vector machine (SVM) is put forward firstly to enhance the quality of product in hot strip rolling. Meanwhile, for enriching data information and ensuring data quality, experimental data were collected from a hot-rolled plant to set up prediction models, as well as the prediction performance of models was evaluated by calculating multiple indicators. Furthermore, the traditional SVM model and the combined prediction models with particle swarm optimization (PSO) algorithm and the principal component analysis combined with cuckoo search (PCA-CS) optimization strategies are presented to make a comparison. Besides, the prediction performance comparisons of the three models are discussed. Finally, the experimental results revealed that the PCA-CS-SVM model has the highest prediction accuracy and the fastest convergence speed. Furthermore, the root mean squared error (RMSE) of PCA-CS-SVM model is 2.04 µm, and 98.15% of prediction data have an absolute error of less than 4.5 µm. Especially, the results also proved that PCA-CS-SVM model not only satisfies precision requirement but also has certain guiding significance for the actual production of hot strip rolling.
      PubDate: 2021-08-01
      DOI: 10.1007/s11771-021-4773-z
       
  • Quantitative analysis on microstructure and high temperature fracture
           mechanism of 2.6vol%TiBw/Ti6Al4V composites with equiaxed microstructure
           after heat treatment

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      Abstract: Abstract In this paper, the 2.6vol%TiBw/Ti6Al4V composites with network architecture were fabricated by hot press sintering (HPS) at 1100 °C for 1 h, and the quantitative relationships between phases and heat treatment temperatures were established. The results showed that the volume fraction phases changed linearly with a range of solution temperature (930–1010 °C) and aging temperature (400–600 °C). Moreover, the composites with equiaxed microstructure were obtained due to the static recrystallization after solution treated at 950 °C for 1 h and aging treated at 600 °C for 12 h. The ultimate high temperature tensile strengths were 772, 658, 392 and 182 MPa, and the elongations were 9.1%, 12.5%, 28.6% and 35.3% at 400, 500, 600 and 700 °C, respectively. In addition, fractured morphology analysis indicated the excellent strengthening effect of TiBw at a temperature below 600 °C. However, the strengthening effect was significantly reduced due to the debonding of matrix and TiBw at 700 °C and caused the cracks to propagate along the grain boundary.
      PubDate: 2021-08-01
      DOI: 10.1007/s11771-021-4771-1
       
  • Adaptive sampling approach based on Jensen-Shannon divergence for
           efficient reliability analysis

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      Abstract: Abstract Extensive studies have been carried out for reliability studies on the basis of the surrogate model, which has the advantage of guaranteeing evaluation accuracy while minimizing the need of calling the real yet complicated performance function. Here, one novel adaptive sampling approach is developed for efficiently estimating the failure probability. First, one innovative active learning function integrating with Jensen-Shannon divergence (JSD) is derived to update the Kriging model by selecting the most suitable sampling point. For improving the efficient property, one trust-region method receives the development for reducing computational burden about the evaluation of active learning function without compromising the accuracy. Furthermore, a termination criterion based on uncertainty function is introduced to achieve better robustness in different situations of failure probability. The developed approach shows two main merits: the newly selected sampling points approach to the area of limit state boundary, and these sampling points have large discreteness. Finally, three case analyses receive the conduction for demonstrating the developed approach’s feasibility and performance. Compared with Monte Carlo simulation or other active learning functions, the developed approach has advantages in terms of efficiency, convergence, and accurate when dealing with complex problems.
      PubDate: 2021-08-01
      DOI: 10.1007/s11771-021-4740-8
       
  • Dual-resource integrated scheduling method of AGV and machine in
           intelligent manufacturing job shop

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      Abstract: Abstract In view of the fact that traditional job shop scheduling only considers a single factor, which affects the effect of resource allocation, the dual-resource integrated scheduling problem between AGV and machine in intelligent manufacturing job shop environment was studied. The dual-resource integrated scheduling model of AGV and machine was established by comprehensively considering constraints of machines, workpieces and AGVs. The bidirectional single path fixed guidance system based on topological map was determined, and the AGV transportation task model was defined. The improved A* path optimization algorithm was used to determine the optimal path, and the path conflict elimination mechanism was described. The improved NSGA-II algorithm was used to determine the machining workpiece sequence, and the competition mechanism was introduced to allocate AGV transportation tasks. The proposed model and method were verified by a workshop production example, the results showed that the dual resource integrated scheduling strategy of AGV and machine is effective.
      PubDate: 2021-08-01
      DOI: 10.1007/s11771-021-4777-8
       
  • Experimental study on bearing capacity of shell strip footings near
           geotextile-reinforced earth slopes

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      Abstract: Abstract From a financial point of view, urbanization frequently enforces the clients to construct superstructures near the slopes, giving rise to increasing the risk of building instability. By conducting a series of small-scale plate load tests, this work aims to investigate the effects of installing geotextile reinforcement layers in sandy slope and reducing the apex angle of triangular shell strip footings. The results show considerable effect of using geotextile-reinforced layers and decreasing the apex angle on the ultimate bearing capacity of shell foundations. With increasing foundation distance from the slope, the adverse effect of the slope is reduced. However, as the distance decreases, the effect of reinforcement and apex angle is increased. For practical applications, empirical equations are also presented for determining the ultimate bearing capacity of the footings and scale effect as well. Finally, 3D numerical simulations are executed and compared with the experimental results.
      PubDate: 2021-08-01
      DOI: 10.1007/s11771-021-4784-9
       
  • Primary and secondary consolidation compression for saturated soil
           considering coupling effect of loading and heating

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      Abstract: Abstract Geotechnical engineering that relates to the energy and environmental problem is receiving more and more attention worldwide. It is of great theoretical and practical value to study the properties of soil under thermal mechanical coupling and its mathematical description. Firstly, based on the general function, a unified primary and secondary consolidation model of saturated soil considering heating temperature is deduced. Combining the existing research achievements, a practical model is obtained which comprehensively reflects the effective stress change, creep and heating effects. After that, a series of thermo-consolidation tests are carried out using a temperature controlled consolidation instrument to study the effects of effective stress, temperature and consolidation duration on saturated soils. The corresponding functional formulas and parameters are obtained thusly. On this basis, the calculation and analysis are carried out to check the reliability and applicability of the newly proposed model. The new model is simple and practical and the parameters are easy to be obtained. And it describes the main law of consolidation compression of saturated soils under the thermal mechanical coupling effect. Therefore, it is suggested for theoretical analysis of thermal geotechnical engineering problems.
      PubDate: 2021-08-01
      DOI: 10.1007/s11771-021-4783-x
       
  • Effect of hot extrusion on microstructure and tribological behavior of
           Al2O3p reinforced 7075 aluminum-matrix composites

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      Abstract: Abstract The effects of hot extrusion and addition of Al2O3p on both microstructure and tribological behavior of 7075 composites were investigated via optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and transmission electron microscopy (TEM). The experimental consequences reveal that the optimal addition of Al2O3p was 2 wt%. After hot extrusion, the Mg(Zn,Cu,Al)2 phases partially dissolve into the matrix and generate many uniformly distributed aging precipitation particles, the Al7Cu2Fe phases are squeezed and broken, and the Al2O3p become uniform distribution. The microhardness of as-extruded 2 wt% Al2O3p/7075 composites reaches HV 170.34, increased by 41.5% than as-cast composites. The wear rate of as-extruded 2 wt% Al2O3p/7075 composites is further lower than that of as-cast composites under the same condition. SEM-EDS analyses reveal that the reinforced wear resistance of composites can put down to the protective effect of the Al2O3p reinforced transition layer. After hot extrusion, the transition layer becomes stable, which determines the reinforced wear resistance of the as-extruded composites.
      PubDate: 2021-08-01
      DOI: 10.1007/s11771-021-4768-9
       
  • Periodic electromagnetic signals as potential precursor for seismic
           activity

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      Abstract: Abstract Electromagnetic signals may be a promising precursor to seismic activity which has been observed in many case studies in past decades. However, the correlation and causation between the electromagnetic signals and the seismic activity are still unclear without intensive observation network. In order to find seismoelectromagnetic phenomenon, we deployed AETA (acoustic and electromagnetic testing all-in-one system), a high-density multi-component seismic monitoring system in the China Earthquake Science Experiment site (CESE, in Sichuan Province and Yunnan Province, China) and the capital circle (areas with a distance which is ≤200 km from Beijing), to record electromagnetic and geo-acoustic data across 0.1 Hz–10 kHz. In the course of data collection, we discovered an electromagnetic waveform that occurs on a daily basis. Because the signal generally coincides with sunrise and sunset, we named this phenomenon the SRSS (Sunrise-Sunset) waveform. After conducting three statistical tests based on seismicity and SRSS, we determined that the SRSS waveform is roughly correlated with the onset of seismic activity. It generally occurs at the regions where seismicity occurs. This discovery might have significant implications with respect to the future of earthquake prediction.
      PubDate: 2021-08-01
      DOI: 10.1007/s11771-021-4739-1
       
  • Microstructure, mechanical properties and corrosion performance of
           selective laser melting Ti/GNPs composite with a porous structure

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      Abstract: Abstract In this study, nano-graphene reinforced titanium matrix composites (GNPs/Ti) with a honeycomb porous structure were fabricated by selective laser melting (SLM). The effects of graphene on the microstructure, mechanical properties and corrosion performance of the SLM GNPs/Ti were systematically investigated. Results of microstructure characterization show that: 1) the density of the SLM GNPs/Ti was improved as compared to that of the SLM Ti; 2) abundant TiC particles were formed in the SLM GNPs/Ti. The hardness and compressive strength of the composite increased by 90% (from HV 236 to HV 503) and 14% (from 277 MPa to 316 MPa), respectively, attributed to the uniformly distributed TiC and fine GNPs in the Ti matrix. Electrochemical tests reveal that the corrosion current density of the SLM GNPs/Ti is only 0.328 μA/cm2, that is about 25% less than that of the SLM Ti. The results indicate that the incorporation of nano-graphene is a potential method to strengthen the Ti by SLM.
      PubDate: 2021-08-01
      DOI: 10.1007/s11771-021-4767-x
       
 
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