Papers by Keyword: Rotational Speed

Abstract: The Friction Stir Welding process has become very popular because it produces good welds with low defects and distortion. However, FSW in thick aluminium alloy plate joints such as those found in applications in the transportation industry such as automotive, rail, shipbuilding, and aircraft is more complex and challenging. Double-sided FSW has challenges to be developed and applied in the transportation industry. This study investigates the effect of different tool rotational speeds on the double-sided FSW of Aluminium Alloy 6061-T6 thick plate. The ratios of the tool speed differences studied were 1:1, 1:1.3, and 1:1.6. Tensile strength, hardness, microstructure evolution, and fracture morphology were studied in this study. The investigation results concluded that an efficient and reliable double-sided FSW joint was achieved at joints with a tool rotational speed difference ratio of 1:1.

Abstract: Torrefaction process is the innovation to improve the properties of biomass. Residence time is one of the parameters that affects the properties of torrefied biomass. The residence time of a rotary kiln is the time of biomass drop into the cylinder until getting out of the cylinder. So, the propose of this study is the effect of lifters, inclination angle and rotational speed on the residence time of a rotary kiln for the torrefaction process. Palm kernel shell was used in this research. Palm kernel was chopped and minced to reduce size. The rotary kiln (0.3 meters diameter 6 meters in length) was used in this research. The number of lifters in this research were 0, 1 and 2. The rotational speed were 1, 2 and 3 rpm. The inclination angle was 1, 3 and 5 degrees. The hopper was used for the feeding system. The time was collected from biomass drop into the cylinder until getting out of the cylinder. The results reveal that the number of lifters, rotational speed and inclination angle affects the residence time of the rotary kiln. The residence time of rotary kiln was an increase when the number of lifters increase. The residence time of the rotary kiln was decreased when the rotational speed and inclination angle increase. It can be concluded that the least residence time of rotary kiln was 86.94 minute at 0 lifters, 3 rpm and 5 degrees. The most residence time was 9.22 minute at 2 lifters, 1 rpm and 1 degree.

Abstract: Friction stir welding (FSW) is one of the new technique for welding materials in solid state welding process. In this proposed work we are using FSW to join the two dissimilar alloys of aluminium. The 6mm thick aluminum plates of aluminium 5086 and aluminum 7075 plates are considered for welding. These have been considered due to their application in various fields. In this experimental process Taguchi’s L9 orthogonal array method is used for optimizing the three process parameters namely rotational speed, axial force and welding speed. To produce a better joint the tensile strength is predicted for the optimum welding parameters and also their percentage of contribution is calculated, by applying the effect of analysis of variance. Depends upon the experimental study, the rotational speed is found better over the other process parameters, which enhances the quality of the weld. The tensile strength has been found for the optimum parameters and the result found during the experiment was 290Mpa which was higher than the base metal strength of aluminium 5086 alloy. The SEM fractograph analysis was done on the optimum parameters welded joints to show the fracture behaviour of tensile test which justifies the visual inspection results of brittle and ductile failures.

Abstract: The development of the friction stir welding being a solid state welding has provided an improved way of manufacturing aluminum joints in a quicker and reliable manner. The heat treatable aluminum alloy AA7075 is used substantially in the aerospace industry because of its high strength to weight ratio and good ductility. The objective of our work is to research the parameters of welding on the mechanical properties of friction stir welded joints of AA7075-T651. The parameters namely rotational speeds (500 rpm, 700 rpm, 900 rpm, 1100 rpm, 1300 rpm and 1500 rpm) were thought-about and table transverse speed of 50 mm/min, axial force of 8 KN is constrained throughout the welding process. The result of these parameters on weld quality is analyzed by its mechanical properties namely micro hardness and tensile strength.

Abstract: Machined product quality depends on its dimension and surface quality. The dimension quality depends on machine tool accuracy while the surface quality depends on machining system stiffness. A low machining system stiffness will shift spindle shaft-tool resonance frequencies to low frequencies. When one of these frequencies coincides with spindle rotational speed or its harmonics, chatter will be generated which in turn worsen the workpiece surface roughness. In addition to increasing machining system stiffness, chatter can be eliminated by decreasing the axial depth of cut as well. Maximum axial depth at certain spindle rotational speed which will not generate chatter is called as chatter threshold. A diagram describing chatter thresholds for certain range of spindle rotational speed is called as a SLD (stability lobe diagram). The diagram is very useful for selecting a maximum depth of cut at certain rotational speed in order to obtain chatter-free machining process. The SLD can be generated theoretically or experimentally. The theoretical one is fast and cheap but it is not guaranteed to be correct. On the other hand, although the experimental one will produce exact values but it is long, cumbersome and expensive, because for certain rotational speed many machining with different axial depth of cut must be conducted until chatter threshold is reached. The same process is then repeated for other rotational speeds. This paper deals with a new method in determining the chatter threshold or SLD experimentally, by using inclined workpiece, by which it only needs one time machining-test for each rotational speed. In this method, during machining process, chatter occurrence is detected by using accelerometer and validated by its surface roughness afterwards. It is shown in this paper that the new method works well for machining aluminium workpiece in vertical machining center.

Abstract: In this paper, vibration analysis of a blade modeled as an anisotropic composite thin-walled beam is carried out. The analytical formulation of the beam is derived for the flapwise bending, chordwise bending and transverse shear deformations. The equations of motion are solved by applying the extended Galerkin method (EGM) for anti-symmetric lay-up configuration that is also referred as Circumferentially Uniform Stiffness (CUS). Consequently, the natural frequencies are validated by making comparisons with the results in literature and it is observed that there is a good agreement between the results. Combined effects of transverse shear, fiber orientation, and rotational speed on the natural frequencies are further investigated.

Abstract: The mechanical properties of weld joints in Friction Stir Welding (FSW) are influenced by the welding parameters such as rotational speed, tool geometry and welding speed. In the present study, three different tool profiles have been used to weld the joints with three different rotational speed and two welding speeds. Full factorial experiments have been conducted using DoE. The mechanical properties of weld joint were evaluated by means of tensile tests and hardness test at room temperature. The experiment result shows that the average highest number of hardness was 40.06 HRB with square tool at a rotational speed of 2000rpm while lowest hardness was 30.84 HRB with cylindrical threaded tool at rotational speed of 1800rpm. The maximum tensile strength of the joint obtained is 265 M Pa which is close to base material strength. It is observed from experimental results that joints made by square tool yield more strength compared to other tool profiles.

Abstract: The effects of the rotating speed of the spindle, the number of the porous medium inserted into the partially porous aerostatic journal bearing and the thickness of the bearing gap on the characteristics of the bearing such as the pressure distribution, the load carrying capacity and the stiffness of the bearing were studied. Based on the finite volume method and the pressure-velocity coupling scheme of the SIMPLE algorithm with the standard k-ε turbulent model, the CFD software was used to solve the Navier-Stokes equations to calculate the pressure field in the bearing gap. The computed results revealed the faster the spindle rotated, the higher the gap pressure. As the gap thickness increased, the gap pressure, the load carrying capacity and the stiffness of the bearing decreased. The more the porous inserts, the higher the gap pressure and the load carrying capacity, but the less the bearing stiffness would be.

Abstract: Functionally Graded Materials (FGM) is a newly evolved concept to get desired properties in the material wherein the intermediate layer is transient since the particle size distribution gradually changes. Centrifugal casting [1] can produce only hollow shapes and Centrifuge casting can produce solid shape FGM very effectively. The study of particle distribution in a fluid using centrifuge casting process is carried out considering sand as particle and its distribution is studied under water, for different viscosity values and for viscosity varying with respect to temperature. Based on centrifugal force and density difference, an attempt has been made to mathematically model the centrifuge casting force to estimate the particle distribution over the length of the specimen and also to assess the influence of process parameters such as rotational speed (G-force) and density of the particles.

Abstract: According to the characteristic of mixing and flocculation of water plant, the calculation formula of the simulation rotational speed of agitator was proposed for the coagulation-flocculation jar test of optimum dosage, which was based on the basic principle that the velocity gradient of production is equal to that of experiment. Obtained the calculation formula for related parameters about coagulation agitator through the determination of the actual production velocity gradient and combined with the coagulation jar test data in laboratory, such as the power consumption of the paddle boards; the proportional coefficient of coagulation agitator and the agitation speed etc. The result shows that the experiment simulation according with the effect of practical produce of water plant can provide the reliable optimum dosage of coagulant for the practical production. This research has a great signality to waste-water treatment, Results not only have great economic benefit, but also can achieve a certain ecological benefit, accorded with the demand of developing low carbon environmental protection.