Showing papers on "Rotational speed published in 2022"

Analysis of Surface Pressure Pulsation Characteristics of Centrifugal Pump Magnetic Liquid Sealing Film

Abstract: In order to discuss the surface pressure pulsation characteristics of the magnetic-fluid sealing membrane of centrifugal pump, this paper studies the surface pressure pulsation characteristics of the shaft end sealing membrane under different flow operating conditions of centrifugal pump based on the combination of numerical calculation and experimental verification. The results show that the pressure value on the surface of the magnetic-fluid sealing film decreases with the increase of the flow rate of the centrifugal pump, and the pressure on the surface of the magnetic-fluid sealing film has periodic pulsation, and the period is the time required for a single blade to sweep the volute separating tongue. In one rotation cycle of the runner, the number of reciprocating movements of the magnetic-hydraulic sealing film is the same as the number of blades of the runner. The main reason for the pressure pulsation is that the impeller periodically sweeps the fixed surface of the centrifugal pump.

Influence of process parameters on the microstructure and mechanical properties of friction stir welds of AA2014 and AA6063 aluminium alloys using response surface methodology

Abstract: Welding dissimilar alloys of aluminium are quite cumbersome due to their lower melting temperatures and difficulty in welding. To resolve this, solid-state procedure friction stir welding (FSW) is utilized largely in industries. In this present research, dissimilar aluminium alloys AA2014 and AA6063 is joined using the FSW procedure to achieve higher yield strength, ultimate tensile strength and microhardness. Experiments were planned as per response surface methodology (RSM) based central composite design (CCD), for four input parameters (tool pin profile, rotational speed, axial force and traverse speed). Micrographs of the weld show grain refinement and proper fusion of materials which increases the mechanical strength and bonding. Outcomes from the experiment show that the considered input parameters significantly influence all the outputs. The optimum condition was evolved from multiobjective optimization procedure using desirability approach (DA) which are 1010 rpm rotating tool speed, 25 mm min−1 as tool traverse speed, 7 kN of axial force with triangular pin profile. The second-order regression model predicts the output responses with lower residuals and the confirmation experiment outputs produces a maximum deviation of 7.94% with investigational outcomes with optimum condition. Micrographs shows that the heat affected zone (HAZ) region is free from voids, oxides, and cracks. The nugget zone has the flow of materials from both the base metals and the flow track is clearly visible.

Study of Cutting Power and Power Efficiency during Straight-Tooth Cylindrical Milling Process of Particle Boards

Abstract: The cutting power consumption of milling has direct influence on the economic benefits of manufacturing particle boards. The influence of the milling parameters on the cutting power were investigated in this study. Experiments and data analyses were conducted based on the response surface methodology. The results show that the input parameters had significant effects on the cutting power. The high rake angle reduced the cutting force. Thus, the cutting power decreased with the increase in the rake angle and the cutting energy consumption was also reduced. The cutting power increased with the rotation speed of the main shaft and the depth of milling induced the impact resistance between the milling tool and particle board and the material removal rate. The p-values of the created models and input parameters were less than 0.05, which meant they were significant for cutting power and power efficiency. The depth of milling was the most important factor, followed by the rotation speed of the main shaft and then the rake angle. Due to the high values of R2 of 0.9926 and 0.9946, the quadratic models were chosen for creating the relationship between the input parameters and response parameters. The predicted values of cutting power and power efficiency were close to the actual values, which meant the models could perform good predictions. To minimize the cutting power and maximize the power efficiency for the particle board, the optimized parameters obtained via the response surface methodology were 2°, 6991.7 rpm, 1.36 mm for rake angle, rotation speed of the main shaft and depth of milling, respectively. The model further predicted that the optimized parameters combination would achieve cutting power and power efficiency values of 52.4 W and 11.9%, respectively, with the desirability of 0.732. In this study, the influence of the input parameters on the cutting power and power efficiency are revealed and the created models were useful for selecting the milling parameters for particle boards, to reduce the cutting power.

Modeling and optimizing the specific cutting energy of medium density fiberboard during the helical up-milling process

Abstract: ABSTRACT Due to the flexible motion characteristics, helical milling could achieve high surface quality and cutting stability. The effects of input parameters on specific cutting energy (SCE) during the medium density fiberboard (MDF) helical up-milling process were studied. Results of analysis of variance showed that the helical angle and depth of milling had extremely significant effects on SCE. SCE increased with increased helical angle, but decreased with increased milling depth. The impact of the rotation speed of the main shaft was non-significant. Due to the highest R2 value, a quadratic model was selected to establish the relationship between input parameters and SCE. The relative errors between predicting results and confirmatory test results were minimal, which meant that the model had high predicting accuracy. Under the selected input parameters, the optimized parameters were 54°, 5500 r/min, 1.5 mm for helical angle, the rotation speed of the main shaft, depth of milling, respectively. Although the arithmetic average of absolute roughness (Ra) and mean peak-to-valley height (Rz) increased about 58.3% and 46.2%, respectively, under the optimal milling parameters, the optimization was feasible at the initial rough machining stage. These results will be beneficial in guiding the selection of processing parameters to achieve reducing SCE.

High-speed friction stir welding in light weight battery trays for the EV industry

Abstract: Present work aims to achieve high welding speed during friction stir welding of lightweight battery trays in the electric vehicle industry. This study reports high-speed friction stir welding (HSFSW) up to 4.0 m min−1 in AA6063-T6 alloys. The defect-free HSFSW joints are produced by adopting aggressive material mixing, i.e. higher tool rotation and plunge force. HSFSW weld cross-section reported an unusual hardness profile of ‘U’ shape instead of ‘W’ shape in conventional FSW of AA6xxx alloys. HSFSW resulted softening of weld stir zone (∼60HV) along with HAZ (∼53HV) against the base material (BM) hardness of ∼90HV. The HSFSW at 4.0 m min−1 obtained good joint strength of 71% of the BM. Microstructure evolutions across the fractured weld cross-section are discussed using EBSD analysis.

Effect of ultrasonic field on microstructure evolution in friction stir welding of dissimilar Al/Mg alloys

Abstract: Understanding of the microstructure evolution and the influence of ultrasonic vibration on friction stir welding (FSW) of dissimilar Al/Mg alloys is of great significance in optimizing the process parameters and improving the joint quality. In this study, the microstructure evolutions in the weld nugget zone (WNZ) of dissimilar Al/Mg joints during FSW and ultrasonic vibration enhanced FSW (UVeFSW) were characterized and compared. It was found that ultrasonic vibration (UV) has great effect on the grains structure of the WNZ in the Mg alloy side. Specially, the exerted UV changed the main dynamic recrystallization (DRX) mechanism of grains in the Mg alloy side from continuous DRX (CDRX) to discontinuous DRX (DDRX) under lower or higher welding speeds but constant tool rotation speed. Along the thickness direction, the average grain sizes near the bonding interface in the WNZ increased first and then decreased, and the maximum grain size was located at the mid-depth of the weld. Low strain shear texture appeared more in the WNZ of the Al alloy side during FSW, while in UVeFSW more locations in the WNZ were with high strain shear textures. The application of UV field improved the DRX degree in the whole weld through promoting the entanglement, aggregation and rearrangement of dislocations.

Magneto-mixed convection in a lid driven partially heated cavity equipped with nanofluid and rotating flat plate

Abstract: In this study, mixed convection in a nanofluid filled cavity induced by thermal buoyancy force, moving wall and rotating flat plate subjected to external magnetic field is numerically investigated. The cavity is partially heated from its bottom wall and cooled from top wall moving with constant velocity in ±x direction and other walls are kept adiabatic. A counter-clockwise rotating flat plate is placed at the centre of the cavity. The cavity is permeated by a transverse magnetic field. Conservation equations are simulated through implementing finite element method. Numerical results are presented using streamlines, isotherms and bar charts to explore the effects of physical parameters on the flow and temperature fields. It is found that flow and thermal fields are impressively affected with the variations in length and speed of rotating flat plate. Besides, higher length and rotational speed of the plate causes maximum amount of heat transfer. Best heat transfer is ensured while the direction of rotating plate is same as the direction of lid wall. Moreover, optimal heat transfer performance is obtained up to 5% nanoparticles concentration which is 123.02% more than base fluid. Higher magnetic field strength attenuates the fluid motion and hence heat transfer rate significantly.

Effect of friction stir processing parameters on the microstructure and properties of ZK60 magnesium alloy

Abstract: Abstract Friction stir processing is an important method for acquiring ultrafine-grained materials. In this paper, 3 mm ZK60 magnesium alloy sheet was carried for friction stir processing. The best processing parameters with a small grain size and maximum mechanical properties were obtained by comparing different rotation speeds and processing speeds. Fine recrystallized grains and high-angle grain boundaries were observed in stirring zone under different processing parameters. With increasing rotation speed, the grain size and high-angle grain boundary ratio increase; while with increasing processing speed, the grain size decrease, and the ratio of high-angle grain boundaries increase. When rotation speed and processing speed are 1400 r·min −1 and 100 mm·min −1 , the processing plate have the largest ultimate tensile strength are 267.52 Mpa, that reached 84.62% of the base metals, and the yield strength, elongation and grain size are 166.97 Mpa, 15.32% and 1.12 ± 1.64 μ m, respectively. The processing plate has more excellent damping performance than rolled.

Impacts of rotating surface and area expansion during nanofluid convection on phase change dynamics for PCM packed bed installed cylinder

Abstract: Phase change dynamics under the rotational surface effects, area expansion and nanoparticle loading in the base fluid are explored for forced convective flow of hybrid nanofluid in a phase change packed bed installed cylindrical reactor. The study is performed with finite element method for different parameters of rotational Reynolds number, fluid stream Reynolds number and concentration of nanoparticle. The hybrid nanofluid properties are based on experimental data for binary particle of Al2O3-TiO2 in 40% ethylene–glycol. Complete phase transition time is estimated with ANFIS based model. The recirculation zone due to the area expansion within the phase change installed region is controlled by the complex interactions between the forced flow, rotation of the surface and nanoparticle amount. Higher values of Reynolds number and nanoparticle concentration result in fast phase change process at rotational Reynolds number of 0 while the effects become reverse in the presence of rotations. Complete phase transition time reduces by about 49% and 10.5% at the highest Reynolds number and at the highest concentration in the absence of rotation while it is increased by about 88% and 6.5% when rotational effects are considered at the highest rotational speed. When only rotational effects are considered, phase change process completion time reduces by about 60% at the highest speed.

Rolling Bearing Condition Monitoring Technique Based on Cage Rotation Analysis and Acoustic Emission

Abstract: The objective of this paper is to present an approach for the detection of change in rolling element bearings (REB) operating conditions that can lead to premature failure. The developed technique is based on the measurement of the kinematics of the bearing cage. The rotational motion of the cage is driven by the traction forces produced in the contacts of the rolling elements with the races. It is known that the cage angular frequency relative to shaft angular frequency is dependent of the bearing load, the bearing speed and the lubrication condition, as these factors are determinant for the lubricant film thickness and the associated traction forces. As an important part of REB failures are caused by misalignment or lubrication problems, any evidence of these conditions should be interpreted as an incipient fault. In this paper a novel method for the determination of the instantaneous angular speed (IAS) of the cage is developed. The method is evaluated in a deep grove ball bearing test rig equipped with the cage IAS sensor, as well as custom acoustic emission (AE) transducer and a piezoelectric accelerometer. The cage IAS is analyzed under different bearing loads and shaft speed, showing the dependence of the cage angular speed with the calculated lubricant film thickness. Typical bearing faulty operating conditions (mixed lubrication regime, lubricant depletion and misalignment) are recreated and it is shown that the cage IAS is dependent on the lubrication regime and is sensitive to misalignment. The AE signal is used as a lubrication regime evaluator as well. Experimental results show that the proposed technique can be used as a condition monitoring tool to detect abnormal REB conditions that can lead to premature failure.

Dynamic Characteristics of a Traction Drive System in High-Speed Train Based on Electromechanical Coupling Modeling under Variable Conditions

Abstract: The traction drive system of a high-speed train has a vital role in the safe and efficient operation of the train. This paper established an electromechanical coupling model of a high-speed train. The model considers the interaction of the gear pair, the equivalent connecting device of the transmission system, the equivalent circuit of the traction motor, and the direct torque control strategy. Moreover, the numerical simulation of the high-speed train model includes constant speed, traction, and braking conditions. The results indicate that the meshing frequency and the high harmonics rotation frequency constitute the stator current. Furthermore, both frequencies are evident during constant speed. However, they are blurry among other conditions except for twice the rotation frequency. Meanwhile, the rotor and stator currents’ root-mean-square (RMS) values during traction are less than the RMS value during braking. The initiation of traction and braking causes a significant increase in current. During the traction and braking process, the RMS value of the current gradually decreases. Therefore, it is necessary to pay attention to the impact of the transition process on system reliability.