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Yang Wang - One of the best experts on this subject based on the ideXlab platform.
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A Research on Surface Morphology of Cutting of Titanium Sheet with Water-Jet Guided Laser and Conventional Laser
Applied Mechanics and Materials, 2011Co-Authors: Chun Qi Li, Li Jun Yang, Yang WangAbstract:Titanium is a class of material difficult to common machine. Laser processing is a feasible method for machining of Titanium. This paper presents cutting investigation of industry pure Titanium Sheet with conventional laser and water-jet guided laser, and analyses their processing features by means of the surface morphology of kerf obtained from Scanning Electron Microscope. The result shows that the machining quality and cleanliness of water-jet guided laser processing is much better than conventional laser processing. The impact and cool effects of the high-speeds water jet are more effective to trim the cut surface and remove molten waster.
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A Research on Surface Morphology of Cutting of Titanium Sheet with Water-Jet Guided Laser and Conventional Laser
Applied Mechanics and Materials, 2011Co-Authors: Chun Qi Li, Li Jun Yang, Yang WangAbstract:Titanium is a class of material difficult to common machine. Laser processing is a feasible method for machining of Titanium. This paper presents cutting investigation of industry pure Titanium Sheet with conventional laser and water-jet guided laser, and analyses their processing features by means of the surface morphology of kerf obtained from Scanning Electron Microscope. The result shows that the machining quality and cleanliness of water-jet guided laser processing is much better than conventional laser processing. The impact and cool effects of the high-speeds water jet are more effective to trim the cut surface and remove molten waster.
Matthias Weiss - One of the best experts on this subject based on the ideXlab platform.
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forming of high strength Titanium Sheet at room temperature
Materials & Design, 2015Co-Authors: Ossama Mamdouh Badr, Bernard Rolfe, Matthias WeissAbstract:Abstract The forming behaviour of high strength Ti–6Al–4V alloy was studied at room temperature. Tensile tests and swing folding trials were performed to determine the mechanical properties and the minimum bending radius of the material. The forming limit diagram (FLD) was established and the springback behaviour of the Ti–6Al–4V analysed via V-die bending tests. The results show that the material has limited formability combined with very low material hardening and a high tendency to springback. This suggests that the stamping or deep drawing of Ti–6Al–4V at room temperature is not possible. Roll forming trials were performed and those show that the Ti–6Al–4V can be roll formed to simple longitudinal sections at room temperature. Improved formability was observed and the tendency to springback in roll forming was significantly lower compared to that determined in V-die bending. Additionally to that the Ti–6Al–4V showed a low tendency for shape defects commonly observed in roll forming due to its high material strength. This suggests that roll forming maybe a potential solution for the room temperature forming of high strength Titanium Sheet to structural sections for the aerospace or automotive industry.
Hirohiko Takuda - One of the best experts on this subject based on the ideXlab platform.
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Crystal-plasticity finite-element simulation of time-dependent springback in a commercially-pure Titanium Sheet
Journal of Physics: Conference Series, 2018Co-Authors: Takayuki Hama, Takeyuki Sakai, Yannis P. Korkolis, Hirohiko TakudaAbstract:A crystal-plasticity finite-element method was used to examine the deformation mechanism of time-dependent springback in a commercially-pure Titanium Sheet. To reproduce the viscoplastic behavior of the Sheet, the material parameters were calibrated to reproduce the strain-rate dependency of the stress-strain curve under uniaxial tension. A two-dimensional draw bending process was simulated and the change in the sidewall curvature was evaluated. The simulation results showed that the curvature increased with the elapsed time after unloading, consistent with experimental results reported elsewhere. The deformation mechanism during the process was discussed in terms of evolution of stress and relative activities of slip and twinning systems.
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time dependent springback of a commercially pure Titanium Sheet
Procedia Engineering, 2017Co-Authors: Takayuki Hama, Takeyuki Sakai, Yusuke Fujisaki, Hitoshi Fujimoto, Hirohiko TakudaAbstract:Abstract Time-dependent springback of a commercially pure Titanium Sheet was investigated experimentally from the viewpoints of strain rate, holding time at the bottom dead center before unloading, and elapsed time after unloading. A draw-bending test showed that the amount of springback decreased linearly with the holding time before unloading when plotted on logarithmic scale and increased with the elapsed time after unloading. To investigate the mechanism of these results, stress relaxation and creep tests were conducted. The variation of the amount of springback with the holding time corresponded well with that of the stress during stress relaxation. On the other hand, the in-plane anisotropy in the evolution of the amount of springback with the elapsed time did not correspond with that of creep strain. The mechanism of the in-plane anisotropy in the elapsed-time dependency was discussed in terms of the stress relaxation and creep behaviors.
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crystal plasticity finite element analysis of deformation behavior in a commercially pure Titanium Sheet
Journal of Physics: Conference Series, 2016Co-Authors: Takayuki Hama, Akihiro Kobuki, Hitoshi Fujimoto, Hirohiko TakudaAbstract:A crystal-plasticity finite-element method was used to examine the deformation mechanism in a commercially pure Titanium Sheet. The following tension-compression asymmetry was exhibited in the stress-strain curves: the yield stress was larger under tension than under compression, whereas the work-hardening was smaller under tension than under compression. The strain hardening behaviour was predicted qualitatively well using the crystal-plasticity analysis. The simulation results suggested that the tension-compression asymmetry could be explained in terms of the difference in the activity of the twinning systems.
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work hardening and twinning behaviors in a commercially pure Titanium Sheet under various loading paths
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2015Co-Authors: Takayuki Hama, Akihiro Kobuki, Hirotaka Nagao, Hitoshi Fujimoto, Hirohiko TakudaAbstract:Abstract In this study, the work-hardening and twinning behaviors in a commercially pure Titanium Sheet were examined under various loading paths including reverse loading. The yield stress was identical between tension and compression, while the work-hardening was slightly larger during compression than during tension. These tendencies were the same in both the rolling and transverse directions. When the Sheet was subjected to reverse loading, the Bauschinger effect was observed during both tension–compression and compression–tension. The tendency in the Bauschinger effect was nearly independent of the strain path tested in the present study. Concerning the twinning, the activities of { 10 1 ¯ 2 } tensile twinning, { 11 2 ¯ 2 } compressive twinning, and { 11 2 ¯ 1 } tensile twinning were observed during tension. Alternatively, during compression, the activity of { 10 1 ¯ 2 } tensile twinning was observed and was much larger than that during tension. When the Sheet was subjected to tension following compression, detwinning occurred. Although the trend in the activity of twinning was similar to that of a magnesium alloy Sheet, the behavior observed in the stress–strain curves was quite different from that of a magnesium alloy Sheet. Based on the results presented, the effect of twinning and detwinning activities on the work-hardening behavior was discussed.
Toshihiko Kuwabara - One of the best experts on this subject based on the ideXlab platform.
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Measurement of Differential Hardening under Biaxial Stress of Pure Titanium Sheet
IOP Conference Series: Materials Science and Engineering, 2018Co-Authors: Chiharu Nagano, Yuta Shimada, Toshihiko Kuwabara, Ryoji KawamuraAbstract:Biaxial stress tests of a commercially pure Titanium Sheet (JIS #1) using the cruciform specimen and the servo-controlled biaxial testing machine have been carried out in order to elucidate its anisotropic plastic deformation behavior. The geometry of the cruciform specimen is identical to that regulated by the ISO 16842. Nine linear stress paths, σx (rolling direction): σy (transverse direction) = 1:0, 4:1, 2:1, 4:3, 1:1, 3:4, 1:2, 1:4, and 0:1 in the first quadrant of the principal stress space are applied to the cruciform specimens. Contours of plastic work in the principal stress space and the directions of plastic strain rates at selected levels of plastic work have been precisely measured. The range of the equivalent plastic strain applied to the specimens is 0.002 ≤ ≤ 0.01. The shapes of the work contours significantly change with increasing the test material exhibits differential hardening (DH). Using the data of the work contours and the directions of plastic strain rates, the applicability of selected anisotropic yield functions to the accurate prediction of the plastic deformation behavior of the test material is examined.
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Identification of Post-necking Strain Hardening Behavior of Pure Titanium Sheet
Residual Stress Thermomechanics & Infrared Imaging Hybrid Techniques and Inverse Problems Volume 9, 2016Co-Authors: Sam Coppieters, Dimitri Debruyne, Sousi Sumita, Daisaku Yanaga, Kristof Denys, Toshihiko KuwabaraAbstract:This paper deals with the identification of the post-necking strain hardening behavior of pure Titanium Sheet. Biaxial tensile tests using a servo-controlled multi-axial tube expansion testing machine revealed that commercial pure Titanium Sheet exhibits significant differential work hardening (DWH). The latter phenomenon implies that the shapes of the work contours significantly change during plastic deformation which is accurately measured in the first quadrant of the stress space up to an equivalent plastic strain of approximately 0.3. In this paper we focus on the plastic material behavior beyond the point of maximum uniform strain in a quasi-static tensile test. To this purpose, the material is subjected to a post-necking tensile experiment during which the strain field in the diffuse necking zone is measured using a dedicated Digital Image Correlation (DIC) system. The key point in the identification of the post-necking strain hardening is the minimization of the discrepancy between the external work and internal work in the necking zone. In this study, we scrutinize the influence of DWH in the pre-necking regime on the identification of the post-necking strain hardening behavior of pure Titanium Sheet. Finally, a strain hardening model which enables disentangling pre- and post-necking hardening behavior is presented.
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Measurement and material modeling of biaxial work-hardening behavior for pure Titanium Sheet
2013Co-Authors: Takeshi Sumita, Toshihiko KuwabaraAbstract:Biaxial tensile tests of a commercial pure Titanium Sheet (JIS ♯1) were performed using a servo-controlled multiaxial tube expansion testing machine developed by one of the authors [Kuwabara, T. and Sugawara, F., Multiaxial tube expansion test method for measurement of Sheet metal deformation behavior under biaxial tension for a large strain range, Int. J. Plasticity, 45 (2013), 103–118]. Tubular specimens with an inner diameter of 54 mm were fabricated by roller bending and TIG welding the as-received test material with a thickness of 0.5 mm. Several linear stress paths in the first quadrant of the stress space were applied to the tubular specimens to measure the contours of plastic work and the directions of the plastic strain rates for an equivalent plastic strain range of 0.05 ≤ e0p ≤ 0.30. It was found that the shapes of the work contours significantly changed with an increase in e0p and that the Yld2000-2d yield function could reproduce the differential work hardening behavior of the test material b...
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measurement of work hardening behavior of pure Titanium Sheet using a servo controlled tube bulge testing apparatus
THE 14TH INTERNATIONAL ESAFORM CONFERENCE ON MATERIAL FORMING: ESAFORM 2011, 2011Co-Authors: Takeshi Sumita, Toshihiko Kuwabara, Yasuhiro HayashidaAbstract:Biaxial stress tests of rolled pure Titanium Sheet (JIS ♯1, 0.5 mm thick) have been carried out in order to investigate the anisotropic plastic deformation under biaxial tension. Rolled pure Titanium Sheet was bent and welded to make tubular specimens. Combined tension‐internal pressure was applied to the tubular specimens using the servo‐controlled tube bulge testing apparatus developed by one of the authors [Kuwabara, T., Yoshida, K., Narihara, K., Takahashi S., Int. J. Plasticity 21 (1), 101–117 (2002)], so that the strain rate ratio, eφ:eθ, in the axial (φ) and circumferential (θ) directions of the specimen was controlled to be constant. Contours of plastic work at different levels of plastic strain and stress paths under constant strain rate ratios have been observed in the first quadrant of stress space. It is found that the test material exhibits significant differential work hardening behavior with the increase of plastic work.
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Measurement of Work Hardening Behavior of Pure Titanium Sheet Using A Servo‐Controlled Tube Bulge Testing Apparatus
2011Co-Authors: Takeshi Sumita, Toshihiko Kuwabara, Yasuhiro HayashidaAbstract:Biaxial stress tests of rolled pure Titanium Sheet (JIS ♯1, 0.5 mm thick) have been carried out in order to investigate the anisotropic plastic deformation under biaxial tension. Rolled pure Titanium Sheet was bent and welded to make tubular specimens. Combined tension‐internal pressure was applied to the tubular specimens using the servo‐controlled tube bulge testing apparatus developed by one of the authors [Kuwabara, T., Yoshida, K., Narihara, K., Takahashi S., Int. J. Plasticity 21 (1), 101–117 (2002)], so that the strain rate ratio, eφ:eθ, in the axial (φ) and circumferential (θ) directions of the specimen was controlled to be constant. Contours of plastic work at different levels of plastic strain and stress paths under constant strain rate ratios have been observed in the first quadrant of stress space. It is found that the test material exhibits significant differential work hardening behavior with the increase of plastic work.
L. Gao - One of the best experts on this subject based on the ideXlab platform.
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numerical simulation and experimental investigation to improve the dimensional accuracy in electric hot incremental forming of ti 6al 4v Titanium Sheet
The International Journal of Advanced Manufacturing Technology, 2014Co-Authors: Guoqiang Fan, L. GaoAbstract:Electric hot incremental forming is feasible and easy to control to form hard-to-form Sheet metals, but the limited accuracy is a major deficiency. In order to find methods to improve precision, single-point electric hot incremental of Ti–6Al–4V Titanium Sheet was numerically simulated using MSC.Marc, and experimental investigations were also carried out in this paper. Through numerical analysis, distributing laws of temperature, thermal strain, stress, and equivalent strain were revealed, and impacts of cold contract and thermal strain on forming were also revealed. Analysis showed that electric hot incremental forming is a complex pyroplastic deformation, and there is a large internal stress in single-point electric hot incremental forming. The incremental Sheet forming region can be divided into three parts: bending deformation at the beginning, shear forming at middle, and reverse bending at last; it is important to enhance the accuracy of the bending part and the reverse bending part, and adequate support must be provided in the beginning to reduce the bending part. In order to form a workpiece with small angle, two-point incremental forming was adopted at first because the gravity of clamp can reduce the reverse bending, then single-point electric hot incremental forming was adopted to enhance the accuracy and reduce internal stress of workpiece.
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Fundamental Studies on Incremental Forming of Titanium Sheet-Metal
Manufacturing Science and Engineering Parts A and B, 2006Co-Authors: Ghulam Hussain, L. GaoAbstract:Several aspects of Incremental Forming, an innovative Sheet-metal-forming process, were studied. Firstly, an optimal combination of tool and lubricant was explored to form the TA1 (commercial Titanium) Sheet-metal parts. Secondly, the effect of the tool diameter on the surface texture of a part was investigated. In addition to this, the influence of the tool diameter on in-plane strain distribution and thickness distribution along a part was also studied. Lastly, experiments were conducted in order to investigate the influence of half-apex angle on thickness distribution along a part to be formed. It has been concluded that the surface coating of Sheet-blanks is essential to form the TA1 parts with good surface textures, and the dispersion of MoS2 powder in grease should be rubbed on the coated surface of the Sheet-blank to provide lubrication between the tool tip (tip of a surface-hardened HSS tool) and the Sheet-blank surface. Furthermore, the tool diameter has no effect on the texture of a formed surface, the deformation mode, and the in-plane strain distribution on a part. It has also been found that the tool diameter does not influence the thickness distribution along a part; rather this is governed by the Sine of half-apex angle of the part to be formed.© 2006 ASME
