Values Of Rotational Speed Research Articles

Application of image processing to radiographic image for quantitative assessment of friction stir welding quality of aluminium 2024 alloy

This work is an attempt to utilize X-ray radiographic image for evaluating friction stir welding process quantitatively rather than qualitatively. The X-ray image from radiographic test is quantified by applying image processing to estimate defect area in terms of number of pixels and compared with mechanical properties of weld joint. Taguchi method is used to design the experiment with input process parameters rotational speed, welding speed and tool offset value. The area of defect from X-ray image and tensile strength of weld joint possess inverse relation. According to Taguchi method, the process parameters that produce minimum area of defect and maximum tensile strength are found to be rotational speed of 1000 rpm, welding speed of 80 mm/min and tool offset at 0 mm from center line. The ANOVA result depicts that welding speed is the dominating parameter for both area of defect and tensile strength followed by rotational speed and tool offset.

Vibration analysis of reconditioned high-speed electric motors

This paper discusses the issue of assessing the condition of three-phase induction motors (which are used as power units for tools on manufacturing lines in the furniture industry) following major repairs. These high-speed motors differ from standard motors in higher frequency power input, more durable bearings and reinforced structure of the terminal part of the rotor shaft. The rotational speed of the rotor is 10,000-18,000 rpm. Such high values of rotational speed trigger a situation in which exceeding the allowable limit of residual unbalance for the rotor unit damages the motor. The damage might necessitate a comprehensive repair. Such cases are frequent. The conducted studies resulted in designing a vibration analysis for assessing the condition of reconditioned high-speed motors (a method for controlling the quality of repairs). Both high- and low-frequency analyses with a signal selection module and the basic general measurements were applied. The analysis provides the possibility of verifying the efficacy of reconditioning in relation to the mechanical validity of the repaired motors.

Adaptive model of the control of roller bit drilling process

The article is devoted to research of the features of roller-bit drilling process control under incomplete information caused by random variation of the drilled rocks properties. It is proposed to optimize control model of the roller-bit drilling process parameters that uses the correction values of axial force and rotational speed of drill bit. The optimization method of operating parameters of roller-bit drilling process is developed and based on the correcting values of axial force and bit rotational speed depending on the technical characteristics of the drilling unit and physic and mechanical rocks properties. The proposed method allows determining the maximum headway per drill bit, drilling speed and its ratio corresponding to the optimum efficiency of the roller-bit drilling process, required for adaptive control of process parameters. The structure of intelligent automated control system of roller-bit drilling process with an adaptive element is developed and this system can adjust and maintain the values of operating parameters correspondingly actual rocks properties for effective process control.

Analysis of quadcopter propeller vibration based on laser vibrometer

An unbalanced propeller can affect a quadcopter’s performance due to vibration, also decreasing its thrust’s yield. Analyses were conducted to determine the correlation between vibration in the dynamic movement of a balanced and an imbalanced propeller using a laser vibrometer (portable digital vibrometer) PDV-100, to determine the correlation between propeller rotational speed and its vibration, as well as to determine the propeller’s maximum rotational speed to avoid over-vibration. The vibration analysis was conducted on a carbon fiber 2-blade propeller by comparing the results of vibration tests with the propeller blade contour. The vibration response of the propeller has been analyzed at three points, respectively the hub, the center, and the tip of the blade, to determine the point having the largest value of the vibration on the propeller running at a maximum rotation speed of 7000 rpm. The same analysis was made on two propellers: the first one of type 1340 with a diameter of 13 inches and the second one of type 1447 with a diameter of 14 inches. The vibration was reduced by propeller’s static balancing, thus increasing the propeller stability. The result showed that an imbalanced propeller generated a decrease in the rotational speed and higher vibration values compared to the balanced propeller. The vibration values showed a linear dependency to the rotor speed; the higher the speed, the bigger the vibration. The limit of rotational speed for the balanced model of the 1340 type propeller was 5000 rpm whilst the corresponding value for the 1447 type propeller was 4500 rpm. Finally, the result was used to optimize the propeller’s overall performance.

Effect of roughness on sealing performance of oil seals with surface texture

PurposeThis paper aims to obtain the film thickness, friction torque and pumping rate and analyze the effects of roughness and surface micro-dimple texture (circular, square and equilateral triangle) on the performance of the oil seal.Design/methodology/approachOn the basis of elastohydrodynamic lubrication and the pumping mechanism of rotating shaft seal, this paper establishes a numerical model of hybrid lubrication of oil seal in sealing area. The model is coupled with fluid mechanics, rough peak contact mechanics and deformation analysis.FindingsThe results show that surface texture significantly improves the lubrication properties of the oil seal. The oil seal with the square texture has the largest oil film thickness, while the equilateral triangle texture has a better effect on the pumping rate.Originality/valueTo get closer to the real working environment of the oil seal, based on the surface roughness, this paper studies the effect of the texture shapes applied to the oil seal lip surface on the performance of the oil seal. The critical roughness and rotational speed values with zero pumping rate are obtained, which provides a theoretical basis for the correct selection of oil seals.

Exhaust emission from a vehicle engine operating in dynamic states and conditions corresponding to real driving

The article presents the exhaust emission results from a diesel engine in dynamic states of engine operation in the driving tests: NEDC (New European Driving Cycle) and Malta test, developed at the Poznan University of Technology. The NEDC and Malta tests were carried out as simulations on the engine test bench mimicking the driving tests conditions. The test results of the emission of carbon monoxide, hydrocarbons and nitrogen oxides obtained in each of the tests were presented. The dynamic states have been classified de-pending on the time derivative value of the torque and engine rotational speed. Both the positive and negative as well as zero time deriv-ative values of torque and rotational speed were considered. Therefore, overall six types of dynamic states were analyzed. A high sensi-tivity of exhaust emission to various types of dynamic states was found. The exhaust emission sensitivity to dynamic states in the Malta test was found to be higher than for the NEDC test, although these tests have similar properties (average rotational speed and average torque). This is due to the fact that the NEDC test is created on the basis of the similarity of zero-dimensional characteristics of the cars speed characteristic, whereas the Malta test was designed in accordance with the principle of faithful representation in the time domain of the NEDC speed curve.

Evaluation of the Hydro—Mechanical Efficiency of External Gear Pumps

This paper proposes and describes a model for evaluating the hydro-mechanical efficiency of external gear machines. The model is built considering and evaluating the main friction losses in the machines, including the viscous friction losses at the tooth tip gap, at the bearing blocks-gears gaps, at the journal bearings, and the meshing loss. To calculate the shear stress at each gap interface, the geometry of the gap has to be known. For this reason, the actual position of the gears inside the pump casing and consequent radial pressure distribution are numerically calculated to evaluate the gap height at the tooth tips. Moreover, the variation of the tilt and reference height of the lateral gaps between the gears and the pump bushings are considered. The shear stresses within the lateral gaps are estimated, for different lateral heights and tilt values. At the journal bearings gaps, the half Sommerfeld solution has been applied. The meshing loss has been calculated according to the suggestion of the International Standards. The hydro-mechanical efficiency results are then discussed with reference to commercial pumps experimentally characterized by the authors in a previous work. The average percentage deviation from experimental data was around 2%, without considering the most critical operating conditions (high delivery pressure, low rotational speed). The limits of this approach are also explained. Finally, the role of each source of loss is discussed, considering different operating conditions and two values of fluid viscosity. Lateral gap losses and meshing loss are much more relevant in determining the hydro-mechanical efficiency variation in the pump’s operating range, especially at a low delivery pressure. Moreover, while lateral gap losses increase with the rotational speed, the meshing loss shows the opposite behavior. The tooth tip gap losses are never as relevant, but they increase at high pressure. The journal bearings losses become comparable with the lateral and meshing ones at high delivery pressure values. Considering the pumps analyzed and the operating range of delivery pressure values and rotational speed values, the meshing loss made the mechanical efficiency vary in a percentage range of ±7%, with lateral losses in the range of about the ±15%, when also considering the extreme operating points (low speed, high pressure; high speed, low pressure). The weight of the lateral losses slightly reduced when we analyzed the higher temperature results, while the meshing losses slightly increased.

Weldability of AA6061-T6 and AISI 304 by underwater friction stir welding

Quality of friction stir welded structures made of thin sheets of aluminium alloy and steel in air medium is affected by several welding defects, inter-metallic compounds and weak heat affected zone, which causes poor weld strength. The present experimental investigation has been carried out to study the feasibility of underwater friction stir welding (UwFSW) between AA6061-T6 and AISI 304 at different values of tool rotational speed and plunge depth. In UwFSW, less heat inhibits the formation of thick inter-metallic compounds, welding defects. In addition, faster cooling rate in UwFSW produces fine microstructure in the weld zone. In the present study, authors have attempted to characterize the various types of weld defects, microstructural changes occurring in conventional friction stir welding in air medium (CFSW) and UwFSW. These results have been used to understand the variation in the weld strength and the microhardness obtained in CFSW and UwFSW at different values of tool rotational speed and plunge depth. Results have revealed the presence of various types of defects such as void, micro-cavity, kissing bond, and Lazy S in the weld region. Further, X-ray micro computed tomography (X-ray micro CT) test on the CFSWed and UwFSWed samples revealed the presence of welding defects (porosity) in the stir zone. UwFSW reduced the weld porosity, thickness of intermetallic compound and yielded fine microstructure which collectively improved the weld strength.

Mixed Convection of Hybrid Nanofluids in an Annulus

In this study, mixed convection in an annulus formed by two horizontal isothermal cylinder surfaces and filled with hybrid nanofluids was examined with Galerkin weighted residual finite element method. The outer cylinder is rotating and inner cylinder is stationary. Influence of Rayleigh number, angular rotational speed of the outer cylinder, eccentricity of the inner cylinder, solid volume fractions of different nanoparticles (alumina, copper, hybrid particles between 0 and 0.02) on the fluid flow and heat transfer characteristics were analyzed. It was observed that average heat transfer enhances with Rayleigh number, solid volume fractions of nanoparticles and eccentricity ratio and reduces as the angular rotational speed of the outer cylinder increases. Adding nanoparticles was found to be advantageous for lower values of Rayleigh number and higher values of angular rotational speed. At the highest volume fraction of Cu nanoparticles, average Nusselt number increases by 31.75 % when the inner cylinder center moves in +y direction. Nanofluid with hybrid nanoparticles gives heat transfer rates which are higher than that of with alumina and lower than that of with copper nanoparticles for the same volume fraction.

Contact Stress Analysis of Spur Gear Under the Different Rotational Speed by Theoretical and Finite Element Method

In this study that spur gears are chosen, contact stress of spur gear is presented under the effect of rotational speed. Three-dimensional simulation of dynamic analysis of gears designed and modeled using ANSYS software. The dynamic analysis included in the determination of dynamic stresses analysis. Contact stress is theoretically calculated and analyzed and numerically estimated using both Hertzian mathematical model and finite element method respectively. Different values of rotational speed used to study its effect on contact stress. Both methods compared by evaluating the percentage error of contact stress, and the modeling of the spur gear and stress analysis of spur gear carried out using SOLID WORK and ANSYS V14, respectively. The most significant note in this study concludes that increasing speed causes vibration and pitting failure due to repetitions.

A novel application of pulse width modulation technique on hydroxy gas production

Software and hardware advancements on a hydroxy gas (HHO) production system is presented in this experimental study. A unique control system that enables to generate hydroxy gas at the specified volumetric flow rates with pulse width modulation (PWM) technique is developed and manufactured. The novelty of the method is automatic control of the hydroxy production according to the instantaneous demand, in other words, the adaptation of the HHO system to the operating principles of internal combustion engines (ICEs). A stepping motor represented the vehicle engine in order to get variable rotational speed values. The instantaneous rotation speed range of the motor divided into four sections as no rotation, low (1000–2001 rpm), middle (2001–4001 rpm) and high (>4001 rpm). A computer-driven microcontroller (MCU) card managed the entire system. The MCU card received motor speed input parameters and identified the PWM signal. Results of the study which are the electrical current, hydroxy gas flow and dry cell temperature ranges are presented in tables and graphs. The measured experimental data were 0–15 A, 0–1.56 L per minute and 24–48 °C for electrical current, hydroxy gas production and dry cell temperature ranges, respectively.

Optimization of friction stir spot welding process parameters for Al-Cu dissimilar joints using the energy of the vibration signals

A friction stir spot welding (FSSW) process for dissimilar aluminum alloy AA1050 and pure copper sheets of 3-mm thickness at different tool rotation speeds between 710 and 1800 rpm and dwell time levels of 0, 5, and 10 s were performed in this study. Empirical relationships were developed to predict the shear failure load (joint strength) and the energy of the vibration signals incorporating two of the most important process parameters, tool rotation speed and dwell time. Process parameters were optimized by using the response surface method (RSM); the optimal values of tool rotation speed and dwell time were 1255 rpm and 4 s, respectively. The parameters optimization results were used in a confirmation test; the dissimilar Al/Cu FSSW joints made with optimal parameters exhibit a good shear failure load. The close relationship between the shear failure load (SFL) of the welded joint and the energy of the vibration signals (EVS) generated during FSSW process was demonstrated. This model can be used to develop and optimize the parameters for automatic control of the FSSW process, based on the vibration signal generated.

Manufacture of absorber fins for solar collector using incremental sheet forming

This article sets out to present a new manufacturing process applied to create absorber fins for solar collectors. Using Incremental Sheet Forming, a flexible process that can be performed at a CNC production center, it is possible to make prototypes of absorber fins with collector riser fittings, which also enables the development of new fin designs using different materials in a wide range of thicknesses. This article analyzes parameters of the Two Point Incremental Forming process, with a partial die for solar collector absorber fin manufacturing using a 1mm thick aluminum AA1200-H14 in order to determine the influence of the step down and the tool's rotation speed on the sheet's formability, being thus able to determine the most appropriate combination of these parameters to obtain a process with the greatest quality and productivity. A series of 16 experiments was proposed to manufacture a small absorber fin comparing the rotation speed values of S = 50, 200, 400, and 800rpm, with step down values of Δz=2, 1, 0.5, and 0.2mm. The feed rate value was kept at F=250mm/min, and each experiment was performed until the first crack occurred in the sheet. In this study, it was possible to indicate the feasibility of the process under more efficient parameters for manufacturing absorber fins using the step down of 2mm and the rotation speed of 50rpm.

Analysis of the pollutants, including polycyclic aromatic hydrocarbons emitted by the internal combustion engine powered by pyrolytic oil

Possibility of powering the compressed combustion engine, 1.9 TDI produced by Volkswagen concern by pyrolytic oil was presented. Three blends with different pyrolytic oil and diesel content were prepared. To compare additionally diesel oil was tested. In researches measurements of concentrations pollutants emitted from the engine such as soot, NOx, CO, CO2 and PAHs were carried out. Also fuel consumption for each fuel was measured. Tests were conducted in chosen engines operation points: two values of rotation speed (1500 and 3000 rpm) and 6 values of torque from minimum value to 150 Nm every 30 Nm. In researches different methods and devices were used such as chromatography method, exhaust analyser and smoke meter. Studies have shown that it was possible to supply the engine by mixture of pyrolytic oil and diesel, but it was justified only in under certain conditions related to the composition of the mixture.

Influence of traction conditions on the power balance in the vehicle 4wd system

Vehicles with the 4WD system of different construction and functional solutions are offered by various manufacturing companies. Users of such vehicles expect continuous improvement of the efficiency in the field conditions while meeting at the same time the ecological requirements. Due to the high reliability and high efficiency in the field conditions the purely mechanical solution systems are often used. The article presents an analysis of the 4WD system operation which uses mechanical solution for torque distribution between drive axes. The tests were carried out on the MAHA LPS 3000 dual-axle chassis dynamometer using the registration of front and rear axle wheels driving forces and rotational speed values. During the experimental tests the vertical wheel loads as well as the tire pressures and the rolling circumferences were being changed. Analysis of the obtained results has served to make an efficiency assessment of the vehicle 4WD transmission system.

Effect of the energy input on the microstructure and mechanical behavior of AA2024-T351 joint produced by friction stir welding

Butt joints of AA2024-T351, with 6 mm thickness, were friction-stir-welded. The objective was to investigate the effects of the energy input on the microstructure and mechanical properties of the joints. The welded joints were tested employing a Mo–Va tool, with shoulder and pin diameter of 15 and 6 mm, respectively. The parameters were selected according to visual inspection of the welds, bending test, and microstructural analysis. Constant values of rotational speed and axial force were employed: 1000 rpm and 13 kN, respectively. The welding speed varied from 3 to 6 mm/s. Temperature measurements were performed along the welding process, analysis by optical microscope, microhardness, and bending tests. The process parameters selected resulted in butt joints with good characteristics, no microvoids, and full penetration. The base metal presented mainly S-type compounds, while in the HAZ thickening and loss of coherence of this precipitates are found. A more refined microstructure was found in the stir zone, based on the CDRX mechanism, with evidences of GDRX in the SZ/TMAZ (AS). As far away from the weld the indentation line is, lower is the hardness of the stir zone. The joints presented a similar increase in the mechanical resistance, with loss in ductility.

Taguchi approach for the optimization of refill friction stir spot welding parameters for AA2198-T8 aluminum alloy

The present study features analytical and experimental results of AA2198-T8 joints produced by the refill friction stir spot welding of 1.6-mm-thick sheets. The selection of proper parameters for this process, such as tool rotational speed (RS), welding time (WT), and tool plunge depth (PD), played an important role in assuring weld strength. In this work, experimental tests were carried out based on the welding conditions according to Taguchi method, in order to determine optimal welding parameters and investigate the effect of those in the joint’s mechanical properties and welded area. Results based on lap shear strength showed that RS and PD were responsible for more than 80% of strength variance, while the analysis based on the stir zone area measurement of the welds endorsed that WT had an insignificant contribution to the strength. Higher strength was correlated to bigger stir zone area, which results from higher RS and PD values.

Effect of Tool Rotational Speed on Friction Stir Welding of ASTM A516-70 Steel Using W–25%Re Alloy Tool

W–25%Re tool was used to friction stir weld ASTM A516-70 steel. This paper presents the results of studying the effects of rotational speed on tool reaction loads, tool wear, weld defects, and weld microstructure. The measured tool axial forces profile were found to be strongly coupled with the weld surface features. At high values of rotational speed, weld microstructure examinations revealed a wide heat-affected zone, coarse grains, and partial dissolving of ferrite and pearlite. These are attributed to the excessive heat generation at high levels of rotational speeds. Stir zone grain refinement occurred at all levels of rotational speeds under investigation, with the finest grains occurring at lower values of the rotational speeds. W–25%Re tool demonstrated excellent wear resistance at low rotational speed. However, at high values of rotational speeds fluctuating loads and high heat input resulted in excessive wear of the tool. Greater amount of wear took place at the tool shoulder, which experienced 50% reduction in the tool shoulder shank. Moreover, elemental diffusion of tungsten occurred into the weld and was found to increase with the increase in tool rotational speed.

The influence of process parameters on mechanical properties and corrosion behavior of friction stir welded aluminum joints

Aim of the present paper is to analyze if and how the process parameters (namely rotational speed S and feed rate f) affect both the mechanical properties and the corrosion behavior of friction stir welded (FSWed) butt joints made of AA7075 and AA2024 alloys and their combination. Tensile tests were performed orthogonally to the welding direction on specimens having the welding nugget placed in the middle of gage length. Rockwell tests were carried out on each specimen moving from the joint axis until the hardness of the base material was reached. A clear dependence of the Ultimate Tensile Strength (UTS) from the process parameters were observed when the joints are obtained using the same material while the effect is not so evident when two different materials are concerned. In almost all cases, the best conditions, in terms of mechanical resistance, were obtained for intermediate values of rotational speed and feed rate. Further tests were performed for evaluating the corrosion behavior and the stress corrosion cracking susceptibility of FSWed joints. In particular, local corrosion potential measurements were executed and longtime immersion tests were carried on four points bending specimens loaded up to 80% of the Yield Strength (TYS), in 35 g/L sodium chloride solution. The same tests were replicated on unloaded specimens. The potential trends are always well defined and much higher for the AA2024 alloy, since it is more noble than the AA7075 alloy. Mixed welding allows to identify the AA7075 alloy as an anode part, having a lower copper concentration and a high concentration of zinc. A correlation of some corrosion behaviors to the mechanical characteristics was evidenced, in particular for the AA2024 alloy.

Electronic Speckle Pattern Interferometry for Vibrational Analysis of Cutting Tools

Abstract A Michelson interferometer based ESPI system for static and vibration out of plane displacement measurements is presented. The aim of the article is to demonstrate the usability of ESPI non-contact measurement method in the field of machining. The correlation fringe patterns were visualized using custom software. The accuracy of ESPI interferometer was verified by the comparison with measurement results collected using industrial XL-80 laser system. The efficacy in vibration analysis was tested by studying the mode shapes and resonant frequencies of the transverse vibrations of square plates. The measurement methodology was used to determine natural frequencies and the shapes of vibrational modes of NFTe 100x1.2/64-II circular slitting saw. As a result the values of rotational speed that should be avoided during machining were determined.