期刊
ADVANCED MATERIALS
卷 34, 期 14, 页码 -出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/adma.202200272
关键词
energy absorption; liquid crystal elastomers; metamaterial; power-law relation; stacking effect; viscoelasticity
类别
资金
- Army Research Office [W911NF-17-1-0165]
- Johns Hopkins University Whiting School of Engineering start-up fund
This study reports a unique rate-dependent energy absorption behavior of liquid crystal elastomer (LCE)-based architected materials, showing that the energy absorption density can be modulated by changing the degree of mesogen alignment, loading direction, and beam thickness to achieve more efficient energy absorption.
A unique rate-dependent energy absorption behavior of liquid crystal elastomer (LCE)-based architected materials is reported. The architected materials consist of repeating unit cells of bistable tilted LCE beams sandwiched between stiff supports. The viscoelastic behavior of the LCE causes the energy absorption to increase with strain rate according to a power-law relationship, which can be modulated by changing the degree of mesogen alignment and the loading direction relative to the director. For a strain rate of 600 s(-1), the unit cell exhibits up to a 5 MJ m(-3) energy absorption density, which is two orders of magnitude higher than the same structure fabricated from poly(dimethylsiloxane) elastomer and is comparable to the dissipation from irreversible plastic deformation exhibited by denser metals. For a multilayered structure of unit cells, nonuniform buckling of the different layers produces additional viscoelastic dissipation. This synergistic interaction between viscoelastic dissipation and snap-through buckling causes the energy absorption density to increase with the number of layers. The sequence of cell collapse can be controlled by grading the beam thickness to further promote viscous dissipation and enhance the energy absorption density. It is envisioned that the study can contribute to the development of lightweight extreme energy-absorbing metamaterials.
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