A metastableβTi alloy was additively manufactured by laser powder bed fusion(LPBF).Tensile testing along the build direction of the as-LPBF material(LPBF-0°)revealed signifcant work softening immediately followi...A metastableβTi alloy was additively manufactured by laser powder bed fusion(LPBF).Tensile testing along the build direction of the as-LPBF material(LPBF-0°)revealed signifcant work softening immediately following yielding with no uniform deformation.By contrast,substantial work hardening and uniform elongation well over 10%were achieved perpendicular to the build direction(LPBF-90°).Similar effects were obtained in the build direction after super transus heat treatment(LPBF-0°+HT)although the strength was slightly lowered.In addition,the yield drop phenomenon observed in both orientations of the as-LPBF materials disappeared after HT.The enhanced work hardening ability,and thus ductility,can be attributed to increased interactions of slip bands/slip bands owing to additional{112}<111>slip systems becoming operative in LPBF-0°+HT and LPBF-90°while LPBF-0°was dominated by{110}<111>only.The other variations after HT may be related to the coarsening of grain structure and removal of specifc substructures in the as-LPBF microstructure.展开更多
Wake structures and vortex induced vibration （VIV） of a spring-supported wide-D-section cylinder were experimentally investigated using an X-wire, a novel phase-locked particle image velocimetry （PIV）, and an acce...Wake structures and vortex induced vibration （VIV） of a spring-supported wide-D-section cylinder were experimentally investigated using an X-wire, a novel phase-locked particle image velocimetry （PIV）, and an acceleration sensor at a low speed wind tunnel. Compared with the fixed case, the 2P （two pair） vortex mode as defined by Govardhan and Williamson （2000） rather than S （single vortex） mode exists in the wake. The velocity deficit behind the cylinder is much larger than that of fixed case. The mean drag coefficient increases from 1.42 for the fixed case to 1.64 for the vibrating case. The Reynolds stress presents even distribution and small with increased distance of X/D = -2 to X/D = -10. The power spectra density based on accelerator and hot wire data presents a highlight identical. It shows that after a strong interaction the cylinder vibration and the vortex shedding come to a stable state. The vortex sheddin~ is totally locked on and controlled by the cylinder vihratinn.展开更多
基金supported by the Australian Research Council(No.DP190103557)the University of Melbourne(No.ECRG20)。
文摘A metastableβTi alloy was additively manufactured by laser powder bed fusion(LPBF).Tensile testing along the build direction of the as-LPBF material(LPBF-0°)revealed signifcant work softening immediately following yielding with no uniform deformation.By contrast,substantial work hardening and uniform elongation well over 10%were achieved perpendicular to the build direction(LPBF-90°).Similar effects were obtained in the build direction after super transus heat treatment(LPBF-0°+HT)although the strength was slightly lowered.In addition,the yield drop phenomenon observed in both orientations of the as-LPBF materials disappeared after HT.The enhanced work hardening ability,and thus ductility,can be attributed to increased interactions of slip bands/slip bands owing to additional{112}<111>slip systems becoming operative in LPBF-0°+HT and LPBF-90°while LPBF-0°was dominated by{110}<111>only.The other variations after HT may be related to the coarsening of grain structure and removal of specifc substructures in the as-LPBF microstructure.
基金supported by the National Natural Science Foundation of China(11472158)
文摘Wake structures and vortex induced vibration （VIV） of a spring-supported wide-D-section cylinder were experimentally investigated using an X-wire, a novel phase-locked particle image velocimetry （PIV）, and an acceleration sensor at a low speed wind tunnel. Compared with the fixed case, the 2P （two pair） vortex mode as defined by Govardhan and Williamson （2000） rather than S （single vortex） mode exists in the wake. The velocity deficit behind the cylinder is much larger than that of fixed case. The mean drag coefficient increases from 1.42 for the fixed case to 1.64 for the vibrating case. The Reynolds stress presents even distribution and small with increased distance of X/D = -2 to X/D = -10. The power spectra density based on accelerator and hot wire data presents a highlight identical. It shows that after a strong interaction the cylinder vibration and the vortex shedding come to a stable state. The vortex sheddin~ is totally locked on and controlled by the cylinder vihratinn.
