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Anthony P Reynolds - One of the best experts on this subject based on the ideXlab platform.
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effects of forge axis force and Backing Plate thermal diffusivity on fsw of aa6056
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2012Co-Authors: Piyush Upadhyay, Anthony P ReynoldsAbstract:Using three sets of tool rotation rate and welding speed, series of friction stir welds were made at various forge axis forces on different Backing Plates with widely varying thermal diffusivity on 4.2 mm thick AA6056. Temperature during the process was measured at the probe core using a thermocouple. Because of the use of different Backing Plates and forge forces it was possible to obtain a relatively wide range of peak temperature in the nugget. This provided a unique opportunity to investigate changes in joint microstructure and property (1) over a wide range of peak temperature while keeping welding and rotational speed constant (2) at similar peak temperature with different welding and rotational speeds. The results show that for the studied gauge thickness, metallurgically significant temperature variations can be achieved without changing the rotation and welding speed while producing defect free welds. The Backing Plate conductivity and forge force both independently affect the weld process parameters such as nugget temperature and tool torque significantly. A significant increase in the tool torque and hence power is observed with the increase in the forge force alone.
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prediction of temperature distribution and thermal history during friction stir welding input torque based model
Science and Technology of Welding and Joining, 2003Co-Authors: Mir Zahedul H Khandkar, Jamil A Khan, Anthony P ReynoldsAbstract:AbstractA novel three-dimensional thermal model is proposed to study the transient temperature distributions during the friction stir welding of aluminium alloys. The moving heat source engendered by the rotation and linear traverse of the pin tool has been correlated with the actual machine power input. This power, obtained from experimental investigation, has been distributed to the different interfaces formed between the tool and the weldpiece based on the torques generated at different tool surfaces. Temperature dependent properties of the weld material have been used for the finite element based numerical modelling. Good agreement between the simulated temperature profiles and experimental data has been demonstrated. The effects of various heat transfer conditions at the bottom surface of the workpiece, thermal contact conductances at the interface between the workpiece and Backing Plate and different Backing Plate materials on the thermal profile in the weld material have also been investigated nume...
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visualisation of material flow in autogenous friction stir welds
Science and Technology of Welding and Joining, 2000Co-Authors: Anthony P ReynoldsAbstract:AbstractMaterial flow in friction stir welds has been visualised using embedded marker materials. The fidelity of the visualisation technique has also been demonstrated. Results from the flow visualisation show that the friction stir welding process can be roughly described as an in situ extrusion process wherein the tool shoulder, the weld Backing Plate, and the cold base metal outside the weld zone form an ‘extrusion chamber’ which moves relative to the workpiece. Deviation from this description occurs primarily at the top surface of the weld where significant material transport occurs owing to the action of the rotating tool shoulder. The transport caused by the shoulder leads to a small amount of circulation about the longitudinal axis of the weld with material moving primarily from trailing to leading sides at the top of the weld and primarily from leading to trailing near the middle and bottom of the weld.
Y J Chao - One of the best experts on this subject based on the ideXlab platform.
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improving mechanical properties of friction stir welded aa2024 t3 joints by using a composite backPlate
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2014Co-Authors: Zhongxi Zhang, Y Feng, Y J ChaoAbstract:Abstract During friction stir welding (FSW) of AA2024-T3 sheets, composite Backing Plates (CBP) made out of the combination of pure copper and medium carbon steel were employed aiming at enhancing the joint mechanical properties. Three different CBP designs were used. Microstructure and mechanical properties of the welded joints were examined. Results reveal that the grains under CBP have been noticeably refined compared to those under a monolithic steel Backing Plate typically used in FSW. In addition, using the CBP effectively prevents the dissolution of Guinier–Preston–Bagaryatskii (GPB) zones in the HAZ. Superior strength–ductility synergy was obtained under CBP-3. Those joints exhibit more high-angle grain boundaries, ultrafine grains of about 980 nm, more GPB zones and optimum hardness distribution, resulting in a tensile strength of 442 MPa and an elongation of as much as 16.2%.
Kocagul Mustafa - One of the best experts on this subject based on the ideXlab platform.
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Flow Resistance Coefficients of Porous Brush Seal as a Function of Pressure Load
'ASME International', 2018Co-Authors: Dogu Yahya, Sertcakan, Mustafa C., Gezer Koray, Kocagul MustafaAbstract:Dogu, Yahya/0000-0003-0474-2899WOS: 000444148300014Developments in brush seal analyses tools have been covering advanced flow and structural analyses since brush seals are applied at elevated pressure loads, temperatures, surface speeds, and transients. Brush seals have dynamic flow and structural behaviors that need to be investigated in detail in order to estimate final leakage output and service life. Bristles move, bend, and form a grift matrix depending on pressure load. The level of pressure load determines the tightness of the bristle pack, and thus, the leakage. In the computational fluid dynamics (CFD) analyses of this work, the bristle pack is treated as a porous medium. Based on brush seal test data, the flow resistance coefficients (FRC) for the porous bristle pack are calibrated as a function of pressure load. A circular seal is tested in a static test rig under various pressure loads at room temperature. The FRC calibration is based on test leakage and literature-based axial pressure distribution on the rotor surface and radial pressure distribution over the Backing Plate. The anisotropic FRC are treated as spatial dependent in axisymmetrical coordinates. The fence height region and the upper region of bristle pack have different FRC since the upper region is supported by Backing Plate, while bristles are free to move and bend at the fence height region. The FRC are found to he almost linearly dependent on the pressure load for investigated conditions. The blow-down is also calculated by incorporating test leakage and calibrated FRC.Turkish Ministry of Science, Industry and Technology, Ankara, Turkey; TUSAS Engine Industries, Inc. (TEI), Eskisehir, TurkeyThis work was funded by "Turkish Ministry of Science, Industry and Technology, Ankara, Turkey" and "TUSAS Engine Industries, Inc. (TEI), Eskisehir, Turkey.
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Computational Fluid Dynamics Investigation of Brush Seal Leakage Performance Depending on Geometric Dimensions and Operating Conditions
'ASME International', 2016Co-Authors: Dogu Yahya, Sertcakan, Mustafa C., Bahar, Ahmet S., Piskin Altug, Arican Ercan, Kocagul MustafaAbstract:Dogu, Yahya/0000-0003-0474-2899WOS: 000371125300019Brush seals require custom design and tailoring due to their behavior driven by flow dynamic, which has many interacting design parameters, as well as their location in challenging regions of turbomachinery. Therefore, brush seal technology has not reached a conventional level across the board standard. However, brush seal geometry generally has a somewhat consistent form. Since this consistent form does exist, knowledge of the leakage performance of brush seals depending on specific geometric dimensions and operating conditions is critical and predictable information in the design phase. However, even though there are common facts for some geometric dimensions available to designers, open literature has inadequate quantified information about the effect of brush seal geometric dimensions on leakage. This paper presents a detailed computational fluid dynamics (CFD) investigation quantifying the leakage values for some geometric variables of common brush seal forms functioning in some operating conditions. Analyzed parameters are grouped as follows: axial dimensions, radial dimensions, and operating conditions. The axial dimensions and their ranges are front Plate thickness (z(1) = 0.040-0.150 in.), distance between front Plate and bristle pack (z(2) = 0.010-0.050 in.), bristle pack thickness (z(3) = 0.020-0.100 in.), and Backing Plate thickness (z(4) = 0.040-0.150 in.). The radial dimensions are Backing Plate fence height (r(1) = 0.020-0.100 in.), front Plate fence height (r(2) = 0.060-0.400 in.), and bristle free height (r(3) = 0.300-0.500 in.). The operating conditions are chosen as clearance (r(0) = 0.000-0.020 in.), pressure ratio (Rp = 1.5-3.5), and rotor speed (n = 0-40 krpm). CFD analysis was carried out by employing compressible turbulent flow in 2D axisymmetric coordinate system. The bristle pack was treated as a porous medium for which flow resistance coefficients were calibrated by using literature based test data. Selected dimensional and operational parameters for a common brush seal form were investigated, and their effects on leakage performance were quantified. CFD results show that, in terms of leakage, the dominant geometric dimensions were found to be the bristle pack thickness and the Backing Plate fence height. It is also clear that physical clearance dominates leakage performance, when compared to the effects of other geometric dimensions. The effects of other parameters on brush seal leakage were also analyzed in a comparative manner.Turkish Ministry of Science, Industry and Technology"Ministry of Science, Industry & Technology - Turkey; "TUSAS Engine Industries, Inc. (TEI), Eskisehir, Turkey"This work was funded by "Turkish Ministry of Science, Industry and Technology," and "TUSAS Engine Industries, Inc. (TEI), Eskisehir, Turkey.
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CFD INVESTIGATION OF BRUSH SEAL LEAKAGE PERFORMANCE DEPENDING ON GEOMETRIC DIMENSIONS AND OPERATING CONDITIONS
Amer Soc Mechanical Engineers, 2015Co-Authors: Dogu Yahya, Sertcakan, Mustafa C., Bahar, Ahmet S., Piskin Altug, Arican Ercan, Kocagul MustafaAbstract:ASME Turbo Expo: Turbine Technical Conference and Exposition -- JUN 15-19, 2015 -- Montreal, CANADADogu, Yahya/0000-0003-0474-2899WOS: 000377639300035Brush seals require custom design and tailoring due to their behavior driven by flow dynamic, which has many interacting design parameters, as well as their location in challenging regions of turbomachinery. Therefore, brush seal technology has not reached a conventional level across the board standard. However, brush seal geometry generally has a somewhat consistent form. Since this consistent form does exist, knowledge of the leakage performance of brush seals depending on specific geometric dimensions and operating conditions is critical and predictable information in the design phase. However, even though there are common facts for some geometric dimensions available to designers, open literature has inadequate quantified information about the effect of brush seal geometric dimensions on leakage. This paper presents a detailed CFD investigation quantifying the leakage values for some geometric variables of common brush seal forms functioning in some operating conditions. Analyzed parameters are grouped as follows; axial dimensions, radial dimensions and operating conditions. The axial dimensions and their ranges are front Plate thickness (z(1)=0.040-0.150in.), distance between front Plate and bristle pack (z(2)=0.010-0.050in.), bristle pack thickness (z(3)=0.0200.100in.), and Backing Plate thickness (z(4)=0.040-0.150in.). The radial dimensions are Backing Plate fence height (r(1)=0.020-0.100in.), front Plate fence height (r(2)=0.060-0.400in.), and bristle free height (r(3)=0.300-0.500in.). The operating conditions are chosen as clearance (r(0)=0.0000.020in.), pressure ratio (R-p=1.5-3.5), and rotor speed (n=0-40krpm). CFD analysis was carried out by employing compressible turbulent flow in 2-D axi-symmetric coordinate system. The bristle pack was treated as a porous medium for which flow resistance coefficients were calibrated by using literature based test data. Selected dimensional and operational parameters for a common brush seal form were investigated, and their effects on leakage performance were quantified. CFD results show that, in terms of leakage, the dominant geometric dimensions were found to be the bristle pack thickness and the Backing Plate fence height. It is also clear that physical clearance dominates leakage performance, when compared to the effects of other geometric dimensions. The effects of other parameters on brush seal leakage were also analyzed in a comparative manner.Int Gas Turbine Ins
J Chen - One of the best experts on this subject based on the ideXlab platform.
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investigation of material deformation mechanism in double side incremental sheet forming
International Journal of Machine Tools & Manufacture, 2015Co-Authors: Y Fang, J ChenAbstract:Double side incremental forming (DSIF) is an emerging technology in incremental sheet forming (ISF) in recent years. By employing two forming tools at each side of the sheet, the DSIF process can provide additional process flexibility, comparing to the conventional single point incremental forming (SPIF) process, therefore to produce complex geometries without the need of using a Backing Plate or supporting die. Although this process has been proposed for years, there is only limited research on this process and there are still many unanswered open questions about this process. Using a newly developed ISF machine, the DSIF process is investigated in this work. Focusing on the fundamental aspects of material deformation and fracture mechanism, this paper aims to improve the understanding of the DSIF process. Two key process parameters considered in this study include the supporting force and relative position between master and slave tools. The material deformation, the final thickness distribution as well as the formability under varying conditions of these two process variables are investigated. To obtain a better understanding from the experimental results, an analytical model has been developed to evaluate the stress state in the deformation zone. Using the developed model, an explicit relationship between the stress state and key process parameters can be established and a drop of stress triaxiality can be observed in the double contact zone, which explains the enhanced formability in the DSIF process. Based on the analytical and experimental investigation, the advancements and challenges of the DSIF process are discussed with a few conclusions drawn for future research.
Seiji Katayama - One of the best experts on this subject based on the ideXlab platform.
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single pass hybrid laser arc welding of 25 mm thick square groove butt joints
Materials & Design, 2016Co-Authors: M Wahba, Masami Mizutani, Seiji KatayamaAbstract:Abstract An innovative hybrid laser-arc welding technique has been developed for one-pass welding of 25 mm thick steel Plates. The parts to be welded were assembled into a butt joint configuration with a square groove and 2.5 mm air gap. A Backing method was applied using ceramic strip or submerged arc welding flux. Cut-wire particles were inserted into the joint gap to protect the Backing material from laser radiation and in the same time help to fill the gap. Laser power density was optimized to obtain full penetration joints without damaging the Backing material. Defect-free joints with adequate fusion zone profiles and good mechanical properties were successfully produced. The technique was then applied to weld 50 mm thick Plates in two welding passes. Using the same joint design, one welding pass was overlaid from one side of the joint and a second pass was deposited from the other side. In this case, a Backing Plate of any material could be used since the laser radiation does not reach the bottom side of the joint.
