The Experts below are selected from a list of 5511 Experts worldwide ranked by ideXlab platform
R. Kegg - One of the best experts on this subject based on the ideXlab platform.
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Composite machine tool Structures for high speed milling machines
CIRP Annals - Manufacturing Technology, 2002Co-Authors: J. D. Suh, D. G. Lee, R. KeggAbstract:To maximize the productivity in machining molds and dies, machine tools should operate at high speeds. However, the productivity of mold manufacturing has not increased significantly because CNC milling machines have massive slides, which do not allow rapid acceleration and deceleration during the frequent starts/stops encountered in machining molds and dies. This paper presents the use of composites for these slides to overcome this limitation. The vertical and horizontal slides of a large CNC machine were constructed by bonding high-modulus carbon-fiber epoxy composite sandwiches to Welded Steel Structures using adhesives. These composite Structures reduced the weight of the vertical and horizontal slides by 34% and 26%, respectively, and increased damping by 1.5 to 5.7 times without sacrificing the stiffness. Without much tuning, this machine had a positional accuracy of ± 5μm per 300 mm of the slide displacement.
J. D. Suh - One of the best experts on this subject based on the ideXlab platform.
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Design and manufacture of composite high speed machine tool Structures
Composites Science and Technology, 2004Co-Authors: D. G. Lee, J. D. Suh, Hak-sung Kim, Jong Min KimAbstract:Abstract The high transfer speed as well as the high cutting speed of machine tools is important for the productivity improvement in the fabrication of molds/dies because non-machining time, called the air-cutting-time, amounts to 70% of total machining time with complex shape products. One of the primary reasons for low productivity is large mass of the moving parts of machine tools, which cannot afford high acceleration and deceleration encountered during operation. Moreover, the vibrations of the machine tool structure are among the other causes that restrict high speed operations. In this paper, the slides of high speed CNC milling machines were designed with fiber reinforced composite materials to overcome this limitation. The vertical and horizontal slides of a large CNC machine were manufactured by joining high-modulus carbon-fiber epoxy composite sandwiches to Welded Steel Structures using adhesives and bolts. These composite Structures reduced the weight of the vertical and horizontal slides by 34% and 26%, respectively, and increased damping by 1.5–5.7 times without sacrificing the stiffness. Without much tuning, this machine had a positional accuracy of ±5 μm per 300 mm of the slide displacement.
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Composite machine tool Structures for high speed milling machines
CIRP Annals - Manufacturing Technology, 2002Co-Authors: J. D. Suh, D. G. Lee, R. KeggAbstract:To maximize the productivity in machining molds and dies, machine tools should operate at high speeds. However, the productivity of mold manufacturing has not increased significantly because CNC milling machines have massive slides, which do not allow rapid acceleration and deceleration during the frequent starts/stops encountered in machining molds and dies. This paper presents the use of composites for these slides to overcome this limitation. The vertical and horizontal slides of a large CNC machine were constructed by bonding high-modulus carbon-fiber epoxy composite sandwiches to Welded Steel Structures using adhesives. These composite Structures reduced the weight of the vertical and horizontal slides by 34% and 26%, respectively, and increased damping by 1.5 to 5.7 times without sacrificing the stiffness. Without much tuning, this machine had a positional accuracy of ± 5μm per 300 mm of the slide displacement.
Manai Asma - One of the best experts on this subject based on the ideXlab platform.
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An analysis of pre-fatigued TIG-treated Welded Structures
'Elsevier BV', 2021Co-Authors: Manai AsmaAbstract:Many existing Steel bridges are approaching, or they have already exceeded their design fatigue life. Assessing and repairing these Structures presents a challenge for the construction industry. In this paper, previous studies, which emphasised treating existing (pre-fatigued) Structures by TIG dressing, are reviewed and analysed. In total, 109 fatigue test results have been studied which employ various Steel qualities, Welded details (longitudinal, transverse, and cover plate) and plate thicknesses. A plot and investigation of the S-N curves were carried out. In addition, a sensitivity analysis of the treated crack depth and the TIG dressing penetration depth was used to establish the extended fatigue life. The performance of TIG dressing in treating existing Structures was examined by simulating a gain factor. It was found that the extension in fatigue life reached 3.4 times the as-Welded fatigue life. This was particularly in cases in which TIG dressing completely removed the initial cracks or missed cracks less than 1 mm deep. Based on the findings, recommendations on treating existing Welded Steel Structures by TIG dressing have been made
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A literature review of pre-fatigued Structures treated by TIG dressing
'Informa UK Limited', 2021Co-Authors: Manai AsmaAbstract:Several fatigue life extension methods of a Welded structure are coveted in the industry such as Tungsten-Inert-Gas dressing (TIG dressing). In this paper, experimental results from literature studies of pre-fatigued Welded Steel Structures treated by TIG dressing were analyzed and showed that TIG dressing efficiency is dependent on the depth of the crack before treatment and the treatment penetration depth (aTIG). A recommendation on the extended fatigue life involves the initial crack size (before treatment) as well as the remaining crack after treatment is provided. Based on this study, the improved fatigue life is found to be at least the as-Welded fatigue life when the cracks have completely re-melted (recalibrated). A significant dependency of extended fatigue life on the remaining crack depth after treatment has been found
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A framework to assess and repair pre-fatigued Welded Steel Structures by TIG dressing
'Elsevier BV', 2020Co-Authors: Manai AsmaAbstract:The extension of fatigue life of ageing Welded Steel Structures is an important challenge faced by the industry. Herein, a detailed framework was developed to assess and improve the performance of these aged Structures (pre-fatigued) using tungsten inert gas (TIG) dressing. Within this framework, relevant damage theories and models were applied to assess the state of pre-fatigued Structures. Based on the results of this assessment and TIG dressing parameters, the extended fatigue life was estimated. Particular attention is paid to the deterministic study of the TIG dressing parameters, which are the fusion depth, weld toe radius, and residual stress. The resulting data, especially longitudinal and transversal attachments, were analysed to verify the proposed framework. The improved fatigue life was found to be at least 3.4 times the as-Welded fatigue life when the cracks were completely re-melted. A significant dependency of the extended fatigue life on the remaining crack length after treatment was observed. A comparison of my predictions with experimentally obtained fatigue lives in other studies showed an absolute error of 20%
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A Literature review for the state of the art: Fatigue life extension of Welded Structures by peening and TIG dressing
2019Co-Authors: Al-karawi Hassan, Manai Asma, Al-emrani MohammadAbstract:Fatigue is one of the most detrimental phenomena that endangersthe life expectancy of Welded Steel Structures. weld is susceptible tofatigue more than other parts because of the high stress concentration,the existing weld defects and the residual stress induced by welding.If the structure is in service, the structure might be already cracked.Different techniques were developed to extend the fatigue life of thestructure and retrofit any existing crack, Peening and TIG remeltingare just examples. A literature study is conducted to establishbetter understand on the effect of these two treatment methods theirefficiency in crack retrofitting.The crack retrofitting experiments consist of two stages, pre-fatigueloading and loading after treatment. The first stage requires crackdetection, different methods were investigated and the most efficientamong them is the use of local strain drop measured by strain gauges.Peening treatment is found to be a function of the crack depth.Retrofitting the crack when it’s still shallow results in longer fatiguelife. The treatment is found to be mainly relying on two effects: thecrack orientation and the introduced residual stress. Peening causesa change in crack orientation which elongate the fatigue life. Thehigher and deeper compressive residual stress causes retardation ofcrack growth and deceleration of crack propagation.TIG remelting is another effecitve method which can retrofit crackdeeper than peening. Its efficiency is a function of the crack depth andthe fusion depth. Usually, the fusion depth is greater than 2mm whichis greater than the peening indentation depth which hardly can reach0.6 mm. In short, TIG is more appropriate to retrofit cracks deeperthan 1mm while Peening results in longer life if the largest crack isshallower than 1mm
Justus Medgenberg - One of the best experts on this subject based on the ideXlab platform.
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on the use of infrared thermography for the analysis of fatigue damage processes in Welded joints
International Journal of Fatigue, 2009Co-Authors: Thomas Ummenhofer, Justus MedgenbergAbstract:Abstract The paper presents an experimental approach for the analysis of localized fatigue damage processes during fatigue testing of Welded Steel Structures by thermographic investigations of thermomechanical coupling phenomena. Special data processing of the recorded infrared sequences is proposed to separate linear and nonlinear damage-indicating effects. The method has been successfully applied to analyze the damage progress during fatigue testing of Welded components. On the tested components localized damage processes could be observed as early as 10–30% of the total fatigue lifetime. The results confirm the high potential of the methodology for the determination of fatigue damage initiation. The technique provides a powerful experimental tool to investigate localized inhomogeneous damage and to analyze complex fatigue processes.
D. G. Lee - One of the best experts on this subject based on the ideXlab platform.
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Design and manufacture of composite high speed machine tool Structures
Composites Science and Technology, 2004Co-Authors: D. G. Lee, J. D. Suh, Hak-sung Kim, Jong Min KimAbstract:Abstract The high transfer speed as well as the high cutting speed of machine tools is important for the productivity improvement in the fabrication of molds/dies because non-machining time, called the air-cutting-time, amounts to 70% of total machining time with complex shape products. One of the primary reasons for low productivity is large mass of the moving parts of machine tools, which cannot afford high acceleration and deceleration encountered during operation. Moreover, the vibrations of the machine tool structure are among the other causes that restrict high speed operations. In this paper, the slides of high speed CNC milling machines were designed with fiber reinforced composite materials to overcome this limitation. The vertical and horizontal slides of a large CNC machine were manufactured by joining high-modulus carbon-fiber epoxy composite sandwiches to Welded Steel Structures using adhesives and bolts. These composite Structures reduced the weight of the vertical and horizontal slides by 34% and 26%, respectively, and increased damping by 1.5–5.7 times without sacrificing the stiffness. Without much tuning, this machine had a positional accuracy of ±5 μm per 300 mm of the slide displacement.
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Composite machine tool Structures for high speed milling machines
CIRP Annals - Manufacturing Technology, 2002Co-Authors: J. D. Suh, D. G. Lee, R. KeggAbstract:To maximize the productivity in machining molds and dies, machine tools should operate at high speeds. However, the productivity of mold manufacturing has not increased significantly because CNC milling machines have massive slides, which do not allow rapid acceleration and deceleration during the frequent starts/stops encountered in machining molds and dies. This paper presents the use of composites for these slides to overcome this limitation. The vertical and horizontal slides of a large CNC machine were constructed by bonding high-modulus carbon-fiber epoxy composite sandwiches to Welded Steel Structures using adhesives. These composite Structures reduced the weight of the vertical and horizontal slides by 34% and 26%, respectively, and increased damping by 1.5 to 5.7 times without sacrificing the stiffness. Without much tuning, this machine had a positional accuracy of ± 5μm per 300 mm of the slide displacement.
