共查询到20条相似文献,搜索用时 15 毫秒
1.
Ahmed O. Al-Roubaiy Saja M. Nabat Andre D. L. Batako 《The International Journal of Advanced Manufacturing Technology》2014,71(9-12):1631-1642
This paper presents a study of friction stir welding of aluminium and copper using experimental work and theoretical modelling. The 5083-H116 aluminium alloy and pure copper were successfully friction-stir-welded by offsetting the pin to the aluminium side and controlling the FSW parameters. A theoretical analysis is presented along with key findings. The process temperatures are predicted analytically using the inverse heat transfer method and correlated with experimental measurements. The temperature distribution in the immediate surroundings of the weld zone is investigated together with the microstructures and mechanical properties of the joint. This was supported by a finite element analysis using COMSOL Multiphysics. In this study, two rotational speeds were used and a range of offsets was applied to the pin. The microstructure analysis of the joints was undertaken. This revealed some particles of Cu inclusion in the nugget zone. The energy dispersive spectroscopy showed a higher diffusion rate of aluminium towards the interface while copper maintained a straight base line. 相似文献
2.
Calibration of dynamic tool–workpiece interface temperature measurement during friction stir welding
《Measurement》2016
The objective of this work is to accurately measure the transient temperatures at the tool–workpiece interface during friction stir welding (FSW) using thermocouples that are embedded in the tool. Temperature sensors embedded in the friction stir (FS) tool provide a non-consumable localized temperature measurement capability that is crucial for process research, development, and control. A modification of the ASTM E-1461 standard for measuring thermal diffusivity with pulses of heat flux is proposed for calibrating the transient response of temperature sensors located near the surface of the FS tool. These tests enable the calculation of each sensor’s time constant, which are used in one-dimensional analytical models of the dynamic response to calculate the true interface temperature. Time constants between 21 and 43 ms are measured for 0.25-mm-diameter, sheathed thermocouples located at the FS tool surface. 相似文献
3.
Axel Fehrenbacher Neil A. Duffie Nicola J. Ferrier Frank E. Pfefferkorn Michael R. Zinn 《The International Journal of Advanced Manufacturing Technology》2014,71(1-4):165-179
A real-time wireless temperature measurement system has been developed and successfully implemented for closed-loop control of tool shoulder–workpiece interface temperature. The system employs two thermocouples in through holes and measures the shoulder and pin interface temperatures with an angular resolution as small as 10°. Both temperatures correlate with weld quality (mechanical testing and weld cross sections), e.g., all welds in 4.76-mm-thick 6061-T6 with an average shoulder interface temperature below 520 °C and an average pin interface temperature below 460 °C fail in the weld zone instead of the heat-affected zone, have unacceptable tensile strengths and in some cases voids. Similarly, welds with shoulder temperatures above the solidus temperature result in a degradation of the weld quality. It was found that a shoulder interface temperature of 533 °C results in the highest weld quality; hence, this temperature should be used as the setpoint temperature in the control system with a constant travel speed of 400 mm/min. The temperature measurement strategy was shown to be able to indicate welds with insufficient shoulder–workpiece contact, thus potentially identifying and preventing welds with detrimental weld quality due to lack of penetration. It was shown that backing plates of different thermal diffusivity change the heat flow out of the weld zone, hence weld temperature, and caused a measurable impact on the weld strength. By changing other process parameters, e.g., through a temperature control system, weld quality can be maintained in the presence of such changing thermal boundary conditions. 相似文献
4.
A. Shahi M. Heydarzadeh Sohi D. Ahmadkhaniha M. Ghambari 《The International Journal of Advanced Manufacturing Technology》2014,75(9-12):1331-1337
Possibility of the formation of Al–Al3Ni composite layers on commercial pure aluminium plates by friction stir processing (FSP) has been studied. It is believed that the hot working nature of FSP can effectively promote the exothermic reaction between Al and added Ni powder to produce Al3Ni intermetallic compounds in the aluminium matrix. In this study, the effects of the rotational and traverse speed of the tool as well as the number of FSP passes on the in situ formation of Al3Ni in aluminum matrix were examined. Besides, the microstructure and microhardness of the fabricated surface layers were also studied. The results showed that the ratio of tool rotational speed to traverse speed (ω/υ) is the main controlling parameter of the heat generated during FSP and hence the reaction between aluminium and nickel. Increasing the number of FSP passes also promoted the reaction between Ni and Al and improved the distribution of Al3Ni compounds, too. The composite layer achieved by six passes of FSP showed the highest hardness, which was almost twice of that of the base metal. 相似文献
5.
《传动技术(上海)》1996,(1)
Preventionofundesiredvibrationsontestbenches¥ZFFredrichshafenAGH.Bertels;A.Klumpp;Abstract:Torsionalvibrationsarealwaysaprobl... 相似文献
6.
In ISO 14405-1, the global sizes, such as least-squares diameter, minimum circumscribed diameter and maximum inscribed diameter are defined. The diameters above can be measured by using cylindrical coordinate measuring method like the circular section measuring method of cylindricity error. The determination method of the least-squares diameter was firstly given based on the cylindrical measuring system, and the optimization models of the minimum circumscribed diameter and the maximum inscribed diameter were built, respectively. The corresponding objective functions were unified as “minimax” expressions. For the four axis parameters of the cylinder with the minimum circumscribed diameter or the maximum inscribed diameter, the searching ranges of cylinder’s axis parameters for their optimal solutions were defined numerically. Thereafter, the genetic, steepest decent and BFGS-0.618 algorithms were introduced, and the optimization evaluation algorithms of two kinds of diameters mentioned above were given. Based on many cylinders’ profiles obtained by the circular section measuring method on a measuring instrument of cylinder’s global sizes which was developed by Zhongyuan University of Technology, Zhengzhou, China. The accuracy, efficiency and suitability of three optimization algorithms were investigated through the evaluation of a lot of the minimum circumscribed diameters and the maximum inscribed diameters. The measurement uncertainty of the global sizes for the cylindrical specimen was analyzed, and the measurement uncertainties of the sizes in the radial and z directions are ±0.95 μm and ±0.5 μm, respectively. The total measurement uncertainties of the global sizes of the cylindrical specimens with the specifications of ϕ10 × 120 mm and ϕ100 × 300 mm are ±3.8 μm and ±5.7 μm, respectively. The investigation results showed that for the evaluation of the globe sizes, any one of three algorithms above is not absolutely prior to the other two algorithms while considering both evaluation accuracy and efficiency, and the difference of their evaluation results do not exceed 0.5 μm. On the other hand, many points between the maximum value and the least value do not affect the evaluation results in optimization process. For improving the evaluation efficiency, by de-selecting those points while considering the characteristic parameter was also studied based on the statistic method and experiment. Coefficient t should be less than 0.3 to ensure the evaluation accuracy. This research may be useful for developing the next generation measurement instrument for the global sizes and the way forward for the digital manufacturing. 相似文献
7.
《Tribology - Materials, Surfaces & Interfaces》2013,7(2):88-101
ABSTRACTAluminium (AA5083)-alumina surface composites are prepared by friction stir processing in two conditions of heat input. The low heat (LH) input conditions is achieved at a rotational speed of 710?rpm and a traverse speed of 100?mm/min, and high heat (HH) input conditions are achieved at a rotational speed of 1400?rpm and a traverse speed of 40?mm/min. The tribological characteristics of aluminium alloy, friction stir processed (FSPed) alloy and FSPed surface composites against steel ball are studied at 5, 10 and 20?N load. While no significant influence is found on frictional behaviour, wear resistance of FSPed composites is superior to FSPed alloys. FSPed composites fabricated at HH input conditions exhibited improved wear resistance as compared to LH input condition. Adhesion and delamination are dominant wear mechanisms at 20?N. Debris particles are reduced in size and hydroxidated in sliding of surface composites. 相似文献
8.
A. K. Lakshminarayanan V. Balasubramanian 《The International Journal of Advanced Manufacturing Technology》2012,59(9-12):961-967
Friction stir welded low chromium AISI 409?M ferritic stainless steel was investigated for susceptibility to intergranular corrosion by oxalic and double-loop electrochemical potentiodynamic reactivation tests, and the degree of sensitization were evaluated by the ratio of the reactivating and activating currents. Stir zone of friction stir welded joint exhibited smaller degree of sensitization compared to the base metal and it is mainly due to fine grains and lower heat input nature of friction stir welding process. Heat-affected zone showed larger current ratio and higher degree of sensitization compared to stir zone and base metal region and not to the extent that has been reported in the literature for arc welding. 相似文献
9.
Zhaomiao LIU Qiuying JIN Chengyin ZHANG Feng SHEN 《Frontiers of Mechanical Engineering》2011,6(2):254
A 3D model of hydrostatic turntable’s oil chamber is established to investigate the lubricants performance with different rheological properties by using FLUENT software and the finite volume method. Newtonian oil and non-Newtonian oil’s performance under varied speeds are compared on the large size hydrostatic turntable system considering the temperature-viscosity relationship and pressure-viscosity relationship. The results show that the property of non-Newtonian fluid viscosity influenced by shear rate largely affects the lubricants performance for most oil added polymer additives. Lubricants cannot simply be regarded as Newtonian fluid. The shear thickening non-Newtonian fluid has a better work property. The results are important to design a large size and high-speed hydrostatic support system, choose lubricant oils, and investigate oil film’s work properties. 相似文献
10.
Elangovan Sooriyamoorthy Shenton Ponnayya John Henry Prakasan Kalakkath 《The International Journal of Advanced Manufacturing Technology》2011,55(5-8):631-640
This study is carried out to optimize the process parameters like weld time, weld pressure, and amplitude of vibration to maximize the weld strength in Al?CAl welding using Taguchi??s design of experiments methodology. Experiments are conducted using 0.3-mm thick pieces of aluminum, and the temperature generated at the weld interface and the weld strength for all the specimens are measured. Also, a finite element model is developed that is capable of predicting the interface temperature and stress distribution during welding. Further, a preliminary study on the joining of alumina to aluminum is also carried out, and the finite element models of temperature and stress distribution during welding are simulated. Results of experimental work and FEM studies are compared and found to be in good agreement. 相似文献
11.
《Tribology - Materials, Surfaces & Interfaces》2013,7(1):37-40
AbstractThe effects of the speed sequence and SiO2 content of Cu–SiO2, sintered by powder metallurgy method, on friction and wear properties have been investigated at fixed speeds. The results indicate that the sequence of speeds employed in the tests plays great roles in the friction and wear properties. When the tests are executed from a lower speed to a higher speed, friction coefficients decrease and oscillate dramatically as the speed goes up, resulting in a severe wear. On the contrary, as the speed starts from a higher value, the friction coefficients are stable and wear is small. These phenomena can be explained by states of third bodies formed in the friction. The third body formed at lower friction speeds is usually granular, which is responsible for the coefficient oscillations and larger wear loss. At higher speeds, the third body formed is rather dense, leading to stable friction coefficients and lower wear loss. 相似文献
12.
Chang Hoon Shin 《Journal of Mechanical Science and Technology》2018,32(4):1613-1623
In recent developments of shale reservoirs, it is important to estimate the permeabilities of hydraulic fractures accompanying the Non- Darcy effects and geometric changes. Accordingly, a new permeability estimation method that considers the varying geometric features under different flow regions is demanded. To this end, the present study introduces the generalized Darcy’s friction flow relation, especially for examining the friction factor-Reynolds number (f · Re) relationship of porous flow, which is originally used in general internal friction flow analyses. Moreover, simple hydraulic fractures comprising structured microbeads are simulated via computational fluid dynamics during fracture aperture variations under different flow conditions from laminar to turbulent. Frictional flow features, e.g., the preservation characteristics of f · Re values, are examined under different geometry and flow conditions, and the transient flow characteristics are investigated using streamline analyses. Consequently, it is verified that the f · Re values vary slightly in proportion to the geometric changes caused by aperture reduction in each medium. Even though the variations in the f · Re values are much smaller than the permeability variations, it seems to be contrary to our expectation. Otherwise, the almost linear-variation aspects of f · Re values were observed in both directional flow cases. The linear-variation aspect of f · Re values is expected to be useful in the permeability-variation estimations in porous media with changing basic geometric factors, such as hydraulic fracture closing. Moreover, it is demonstrated that regardless of aperture reduction in the same type of medium, each porous flow has a very similar power-law relation between f and Re values when the flow velocity changes from the laminar to the turbulent condition. This aspect can be effectively used for obtaining permeability estimations of the varied media, particularly under different flow conditions. 相似文献
13.
14.
Now the researches concerning integral bus mainly focused on design and analysis of overall mechanical property of bus body,and paid little attention to characteristic of local structures,such as joint,plug welding hole,and bolt connection point,etc.So there is much blindness on the design of local connecting structure.Since integral bus body structure cancels large section longitudinal beam,and uses framework made by welding small section bars together as principal part to bear the whole load when the vehicle works,there are many joints receiving high load in the body structure,and local stress concentration can not be avoided.Under such circumstances,by adopting beam-shell mixed model based on super element technique,and selecting a joint commonly used by bus sidewall,the rule of the effect of bar joint’s welding seam spacing on joint’s local mechanical property is investigated in this paper,and the investigating results show that joints have minimum stress concentration with welding seam spacing of 8 mm.To learn whether the above rule is affected by relative bar wall thickness,many groups of bars with different relative bar wall thicknesses are studied experimentally,and the experimental results show that the joints local stress levels vary with different relative bar wall thicknesses,but the rule of the effect of bar joint’s welding seam spacing on joint’s local stress level remains the same.The research is significant for local structure design of bus joint in the future. 相似文献
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16.
R. Venkata Rao V. D. Kalyankar 《The International Journal of Advanced Manufacturing Technology》2013,69(1-4):93-106
Welding aspects of a high-quality Cr–Mo–V steel are investigated in the present work. Cr–Mo–V steel can be suggested as a best choice for fabrication of pressure vessels to be operated in high-temperature operating conditions. Welding of this group of steel demands very critical attention on the parameters setting of chosen welding process. Only a few researchers had carried out research on the optimization aspects of the submerged arc welding of Cr–Mo–V steel. In the present work, complete experimental analysis is carried out on the submerged arc welding of Cr–Mo–V steel. The important input process parameters considered are welding current, voltage, welding speed, and wire feed. The effect of these input parameters is studied on various responses related to weld bead geometry and few mechanical properties. Taguchi’s L9 orthogonal array is used for design of experiment and the mathematical models are developed for the responses using MINITAB 15 software. The models developed are validated by conducting more experiments. Optimised parameter setting is also obtained by using a recently developed teaching–learning-based optimization algorithm. 相似文献
17.
The application of sand particles is a common method to improve the friction of aircraft tires on snow or ice covered runways. Hence, an understanding of the prevailing rubber–ice and sand–ice friction mechanisms is of practical interest. Rubber–ice and sand–ice friction measurements were made with a British Pendulum Tester at temperatures between ?22 and 0 °C and the effect of loose snow contamination on top of the ice was investigated. The results (the response of the instrument) were expressed in a sliding length averaged friction coefficient μBP. Close to the melting point the friction of rubber on ice was low and increased with decreasing ice temperature. Below ?5 °C, reasonably high friction levels (0.2<μBP<0.5) were obtained between rubber and ice, but the friction level dropped drastically by the presence of a very thin layer of snow. The sand–ice friction level was less dependent on ice temperature and clearly not as much affected by the presence of snow, compared to rubber–ice friction. The micromechanisms involved in rubber–ice and sand–ice frictions were investigated by the application of etching and replicating technique (ERT) developed for the examinations of the dynamics of dislocations in ice during deformation. 相似文献
18.
Study on the Effect of Track Curve Radius on Friction-Induced Oscillation of a Wheelset–Track System
AbstractThe purpose of this article is to investigate the correlation between the friction-induced oscillation of a wheelset–track system and curve radius and to explain a general phenomenon of rail corrugation based on the viewpoint of friction-induced oscillation. The typical phenomenon of rail corrugation in metros is that corrugation generally arises when the curve radius is quite small, whereas it rarely occurs when the curve radius is larger or on a straight track. Different multibody models of the vehicle–track system and finite-element models of the multiple-wheelset–track system with different curve radii are established, respectively. According to the creep force analyses and unstable vibration analyses, the correlation between the creep force and friction-induced oscillation can be identified. Then the effect of the track curve radius on the friction-induced oscillation of the wheelset–track system can be summarized, which provides an explanation of the typical phenomenon of corrugation. 相似文献
19.
The effect of adequateness of the calibration equations on measurement uncertainty was not mentioned by EURACHEM. In this work, we investigate the sources of uncertainty when measuring glucose concentration with a UV–Vis spectrophotometer. The effect of two calibration equations on the uncertainty was compared. The sources of the glucose concentration measurement uncertainty include purity, volume of flasks, mass and the calibration equations. The effects of two calibration equations, linear and polynomial equation, on the uncertainty source were evaluated using the inverse calibration equation. The results indicated that the uncertainty components from purity were the smallest. The volumes of the volumetric flasks had only modest effect on the uncertainty, while the mass was an important source of the uncertainty. The contribution of the calibration equation to the total relative measurement uncertainty was 59.39% for the linear equation and 30.34% for the polynomial equation. With the selection of the adequate equation, the uncertainty source of the calibration equation could be reduced significantly. 相似文献
20.
Qingshuai Zhu Xiaoliang Shi Wenzheng Zhai Jie Yao Ahmed Mohamed Mahmoud Ibrahim Zengshi Xu Siyuan Song Abid Qamar ud Din Long Chen Yecheng Xiao Qiaoxin Zhang 《Tribology Letters》2014,55(2):343-352
Research on the friction layer is needed to minimize friction- and wear-related mechanical failures in moving mechanical assemblies. Dry sliding tribological tests of Ni3Al matrix composites (NMCs) with 1.5 wt% graphene nanoplatelets (GNPs) sliding against different counterface balls are undertaken at the condition of 10 N–0.234 m s?1 in this study. When sliding against GCr15 steel, a uniform and thick friction layer is formed, resulting in a lower friction coefficient (0.29–0.31) and wear rate (2.0–3.1 × 10?5 mm3 N?1 m?1). While sliding against Al2O3 and Si3N4, the formation and stability of the friction layers are restricted in the severe wear regime, and the NMCs exhibit higher friction coefficients and wear rates. Therefore, various counterface balls have a great effect on the stability and thickness of the friction layer, thus affecting the tribology performance of NMCs. The result also shows that GNPs exhibit enrichment and self-organized microstructures in the friction layer. In addition, the friction layer is also found to be divided into two layers, protecting the subsurface from further damage and reducing shear. 相似文献