Anionic redox induced anomalous structural transition in Ni-rich cathodes
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99 GENERAL AND MISCELLANEOUS↗
Engineering topics
Song, B.
Publications and source records attributed to Song, B..
Soft elasticity optimises dissipation in 3D-printed liquid crystal elastomers
Soft-elasticity in monodomain liquid crystal elastomers (LCEs) is promising for impact-absorbing applications where strain energy is ideally absorbed at constant stress. Conventionally, compressive and impact studies on LCEs have not been performed given the notorious difficulty synthesizing sufficiently large monodomain devices. Here, we use direct-ink writing 3D printing to fabricate bulk (>cm 3 ) monodomain LCE devices and study their compressive soft-elasticity over 8 decades of strain rate. At quasi-static rates, the monodomain soft-elastic LCE dissipated 45% of strain energy while comparator materials dissipated less than 20%. At strain rates up to 3000 s –1 , our soft-elastic monodomain LCE consistently performed closest to an ideal-impact absorber. Drop testing reveals soft-elasticity as a likely mechanism for effectively reducing the severity of impacts – with soft elastic LCEs offering a Gadd Severity Index 40% lower than a comparable isotropic elastomer. Lastly, we demonstrate tailoring deformation and buckling behavior in monodomain LCEs via the printed director orientation.
36 MATERIALS SCIENCE↗
The effect of a magnetic field gradient on anode double layers
In experiments on anode (ionization) double layers in nonuniform magnetic fields it has been noted that the magnetic field gradient seems to stabilize the double layer position. This effect is further investigated in a Q machine in which the magnetic field geometry could be varied. It is found that the position of the double layers, along the axis of the device, could be controlled by changing the magnetic geometry. This effect is accounted for in a physical model which takes into account the effect of ion reflection by the magnetic mirror force in the region of magnetic field nonuniformity. This model is also able to account for variation of the double layer position when the neutral gas pressure is varied.
Song, B.↗
Ion-acoustic waves in a plasma with negative ions
Propagation and damping of ion-acoustic waves have been investigated in a Q-machine plasma consisting of K(+) positive ions, SF6(-) negative ions, and electrons. The phase velocity of the ion-acoustic 'fast' mode increases with increasing epsilon, the concentration of negative ions. The wave damping decreases with increasing epsilon, and nearly disappears, for the highest wave frequencies investigated, when epsilon is more than about 0.9. Both results are in agreement with predictions from Vlasov theory.
Song, B.↗