turning

车削
  • 文章类型: Journal Article
    Gamma-TiAl (γ-TiAl) alloys can be used in high-end products relevant to the aerospace, defense, biomedical, and marine industries. Fabricating objects made of γ-TiAl alloys needs an additive manufacturing process called Electron Beam Melting (EBM) or other similar processes because these alloys are difficult-to-cut materials. An object fabricated by EBM exhibits poor surface finish and must undergo postprocessing. In this study, cylindrical specimens were fabricated by EBM and post-processed by turning at different cutting conditions (cutting speed, depth of cut, feed rate, insert radius, and coolant flowrate). The EBM conditions were as follows: average powder size 110 μm, acceleration voltage 60 kV, beam current 10 mA, beam scanning speed 2200 mm/s, and beam focus offset 0.20 mm. The surface roughness and cutting force were recorded for each set of cutting conditions. The values of the cutting conditions were set by the L36 Design of Experiment approach. The effects of the cutting conditions on surface roughness and cutting force are elucidated by constructing the possibility distributions (triangular fuzzy numbers) from the experimental data. Finally, the optimal cutting conditions to improve the surface finish of specimens made of γ-TiAl alloys are determined using the possibility distributions. Thus, this study\'s outcomes can be used to develop intelligent systems for optimizing additive manufacturing processes.
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  • 文章类型: Case Reports
    People are required to adapt their basic walking pattern to turn and change directions safely for activities of daily living. This case study describes the changes in neuromuscular control among individuals with stroke on walking paths of different curvatures. Two men with hemiparetic stroke and one control subject walked along a straight, wide curved, and tight curved pathway while muscle activation of the medial and lateral gastrocnemius was recorded, along with the trajectory of the center of pressure (COP) during the single support phase. Balance, sensorimotor control, and functional ambulation were also evaluated. The subject with greater lower-limb sensorimotor impairment displayed a larger difference in the anterior-posterior COP displacement between limbs, which exacerbated as the path curvature increased. In addition, while the control subject demonstrated a lateral shift in the medial-lateral COP position, this person was unable to adapt the COP position on the nonparetic side. The second participant with a stroke demonstrated better balance and lateral shifting of the COP position. Modulation of the COP trajectory is required to safely perform curved walking. Further study is required to confirm the role of stroke-related gait deficits in the ability to adapt to curved walking.
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