Mechanical Properties of Acoustically Levitated Granular Rafts
Mechanical Properties of Acoustically Levitated Granular Rafts
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DOI：
10.1103/physrevx.12.021017
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发表时间：
2022-04-22
影响因子：
12.5
通讯作者：
Jaeger, Heinrich M.
中科院分区：
文献类型：
--
作者：
Lim, Melody X.;VanSaders, Bryan;Jaeger, Heinrich M.
我们研究了一个用于惯性多粒子聚集体旋转动力学的模型系统，其中亚毫米级物体在空气中通过声悬浮。在散射声的驱动下，悬浮颗粒自组装成单粒子层，形成具有声束缚能和弯曲刚度的介观颗粒筏。对声阱进行失谐会产生随机力和扭矩，从而为悬浮物体赋予角动量。随着准二维颗粒筏角动量的增加，颗粒筏会从圆盘状变形为椭圆状，最终像液滴破裂一样分裂成多个独立的颗粒筏。我们提取了颗粒筏的有效表面张力和弹性模量，并表明非成对声力会产生与颗粒筏尺寸成比例的有效弹性模量。我们还表明，颗粒筏的尺寸控制着塑性变形的微观结构基础，从而导致从脆性断裂到延性破坏的转变。
We investigate a model system for the rotational dynamics of inertial many-particle clustering, in which submillimeter objects are acoustically levitated in air. Driven by scattered sound, levitated grains selfassemble into a monolayer of particles, forming mesoscopic granular rafts with both an acoustic binding energy and a bending rigidity. Detuning the acoustic trap can give rise to stochastic forces and torques that impart angular momentum to levitated objects. As the angular momentum of a quasi-two-dimensional granular raft is increased, the raft deforms from a disk to an ellipse, eventually pinching off into multiple separate rafts, in a mechanism that resembles the breakup of a liquid drop. We extract the raft effective surface tension and elastic modulus and show that nonpairwise acoustic forces give rise to effective elastic moduli that scale with the raft size. We also show that the raft size controls the microstructural basis of plastic deformation, resulting in a transition from fracture to ductile failure.