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排序方式: 共有82条查询结果,搜索用时 46 毫秒
31.
This work investigates the effect of SiC particles on the microstructure and mechanical properties of dissimilar friction stir welding between AA6061-T6 and AA2024-T351. Two variations in the size of SiC particles, along the joint line, various groove width, and tool offset, were used for the welding. It was found that the joints made by rotational speed of 800?rev?min?1, travelling speed of 31.5?mm?min?1, groove width of 0.3?mm, and tool offset of 0.5?mm exhibited the most uniform distribution of particles for both micro- and nano-scale SiC particles. Additionally, the smaller and rounded equiaxed particles result in easier material flow, a more uniform metal matrix composite, the smallest grain size in the stir zone and the highest tensile strength. 相似文献
32.
Amir Saghatforoush Masoud Monjezi Roohollah Shirani Faradonbeh Danial Jahed Armaghani 《Engineering with Computers》2016,32(2):255-266
Blasting is the process of use of explosives to excavate or remove the rock mass. The main objective of blasting operation is to provide proper rock fragmentation and to avoid undesirable environmental impacts such as ground vibration, flyrock and back-break. Therefore, proper predicting and subsequently optimizing these impacts may reduce damage on facilities and equipment. In this study, an artificial neural network (ANN) was developed to predict flyrock and back-break resulting from blasting. To do this, 97 blasting works in Delkan iron mine, Iran, were investigated and required blasting parameters were collected. The most influential parameters on flyrock and back-break, i.e. burden, spacing, hole length, stemming, and powder factor were considered as model inputs. Results of absolute error (Ea) and root mean square error (RMSE) (0.0137 and 0.063 for Ea and RMSE, respectively) reveal that ANN as a powerful tool can predict flyrock and back-break with high degree of accuracy. In addition, this paper presents a new metaheuristic approximation approach based on the ant colony optimization (ACO) for solving the problem of flyrock and back-break in Delkan iron mine. Considering changeable parameters of the ACO algorithm, blasting pattern parameters were optimized to minimize results of flyrock and back-break. Eventually, implementing ACO algorithm, reductions of 61 and 58 % were observed in flyrock and back-break results, respectively. 相似文献
33.
Acrylonitrile was copolymerized with two N-arylmaleamic acids and with N-3-carboxyphenylmaleimide in dimethylformamide (DMF) using azobisisobutyronitrile as initiator. The reactivity ratios and the Q-e parameters of these monomers were estimated, and the resulting copolymers were characterized by viscosity measurements and thermal analysis. Thermogravimetry and differential thermal analysis data showed an improvement in the thermal behaviour of the investigated copolymers compared with that of poly(acrylonitrile). Mechanisms illustrating the role of both the acidic group and the maleimide ring in the nitrile oligomerization were proposed. The produced copolymers showed an excellent affinity towards basic dyes and better color fastness towards UV light. 相似文献
34.
35.
Amiri Ahad Masoumi Arian Talebitooti Roohollah 《International Journal of Mechanics and Materials in Design》2020,16(3):569-588
International Journal of Mechanics and Materials in Design - Fluid-conveying micro/Nano structures are key tools in MEMS and NEMS applications especially for drug delivery systems to attack a... 相似文献
36.
Roohollah Jamaati Mohammad Reza Toroghinejad 《Journal of Materials Engineering and Performance》2011,20(2):191-197
It is the objective of this article to investigate the influence of surface preparation on the cold roll bonding (CRB) process.
In this context, the effects of surface preparation parameters consisting of surface preparation method, surface roughness,
scratch-brushing parameters, and the delay time between surface preparation and rolling are investigated on the bond strength
of aluminum strips. The bond strength of two adjacent aluminum strips produced by the CRB process is evaluated by the peeling
test. Furthermore, the interface region is investigated by metallographic observations. Our findings indicate that higher
surface roughness values and shorter delay times improve the bond strength. It is also found that degreasing followed by scratch-brushing
yield the best bonding properties. 相似文献
37.
In this paper the results of numerical study of the mixed convection heat transfer of Al2O3–water nanofluid in a horizontal annuli are presented. Steady, laminar flows in symmetric configurations are considered. Single-phase fluid approach is adopted for nanofluid modeling. The governing equations are discretized using the finite-volume method. A SIMPLE-like algorithm has been applied for pressure–velocity coupling on the collocated arrangement. In order to validate the code performance, the numerical results are compared with those available in the literature and good agreement is achieved. The effects of some important parameters such as nanoparticle volume fraction, aspect ratio, Grashof number, and heat flux ratio are studied and discussed in detail. In general, it is observed that the local Nusselt number increases with increase in nanoparticle concentration, Grashof number, and radius ratio. However, when increasing the nanoparticle concentration there are considerable increments in pressure drop and pumping power, which are not desirable. On the other hand, changes in the skin friction coefficient are negligible. 相似文献
38.
Roohollah Jamaati Mohammad Reza Toroghinejad Hossein Edris 《Journal of Materials Engineering and Performance》2013,22(11):3348-3356
In this study, cold roll bonding process characteristics of IF steel strips, such as bond strength, threshold deformation, undulation of peeling force, and peeled surface, in the presence of SiC nanoparticles were examined and compared to those of an IF steel strip without nanoparticles. The bond strength was evaluated by the peeling test and scanning electron microscopy. It was found that when the thickness reduction was increased, the peeling force of IF steel strips improved. The results also indicated that the presence of silicon carbide nanoparticles decreased the bond strength of IF steel strips when compared to the strips without nanoparticles for the same thickness reduction. When the thickness reduction was increased, the undulation of average peeling force values increased at a constant nanoparticle content. Also, the strips without nanoparticles had a lower undulation value as compared to the strips with SiC nanoparticles. In addition, in the presence of silicon carbide, when the nanoparticles’ content was increased, the undulation of average peeling force values decreased at a constant thickness reduction. Finally, it was found that the bond strength of IF steel strips was less than that of aluminum and copper strips. This was attributed to their crystal structure. 相似文献
39.
Mohammad Reza Toroghinejad Roohollah Jamaati Majid Hoseini Jerzy A. Szpunar Jan Dutkiewicz 《Metallurgical and Materials Transactions A》2013,44(3):1587-1598
In this study, the accumulative roll bonding and folding (ARBF) process was used for manufacturing nanostructured aluminum/copper multilayered composites. Textural evolution during the ARBF process of composites was evaluated using X-ray diffraction. Microstructural observation of some samples was evaluated by scanning electron microscopy and transmission electron microscopy. The ARBF process induced formation of a strong preferred orientation along the β-fiber and also to the pronounced copper texture component. In the aluminum side, occurrence of dynamic recovery reduced the intensity of the β-fiber rolling texture due to change in dislocation structure and decrease in the degree of strain hardening. On the other hand, occurrence of discontinuous dynamic recrystallization at the third and fourth ARBF cycles led to decreasing the intensity of fibers and texture components in the copper side. The average grain sizes of the final sample for the copper and aluminum sides were ~50 and ~200 nm, respectively. 相似文献
40.
Roohollah Jamaati Mohammad Reza Toroghinejad 《Journal of Materials Engineering and Performance》2012,21(6):859-864
In this study, Al/Al2O3 composite strips were produced by the cold roll bonding (CRB) process. Microhardness, tensile strength, and elongation of composite strips were investigated as a result of changes in thickness reduction, quantity of alumina particles, and the production method used. It was found that higher values of reduction and quantities of alumina improved microhardness and tensile strength but decreased elongation. Furthermore, as-received strips exhibited the highest values for microhardness and tensile strength but the lowest for elongation. In contrast, post-rolling annealed strips recorded the lowest values for microhardness and tensile strength but the highest for elongation. Finally, it was found that pre-rolling annealing was the best method for producing this composite via the CRB process. 相似文献