颗粒密度对氧化锆颗粒系统的动力学体积响应的影响

The Effect of the Particle Density on the Spectrum of Dynamical Responses on Packing Volume of the Granular System Composed of Spherical Zirconium Oxide

通过测量了垂直脉冲激励下不同密度的球形氧化锆颗粒体系的动力学体积响应谱,分析了氧化锆颗粒密度对颗粒体系体积响应谱的影响。结果发现,当经历高于临界幅度Γ＊的足够多的脉冲振动后,氧化锆颗粒系统达到了体积分数仅仅依赖激励脉冲幅度Γ0的可逆的、稳定状态。达到稳态的氧化锆颗粒系统的动力学体积响应因子χ~v（Γ0）随脉冲幅度Γ0的变化曲线上存在双峰结构,Γ0大的子峰的相对高度随着氧化锆颗粒密度的减小而增大,暗示该子峰可能起因于颗粒系统内部结构的大规模重排;Γ0小的子峰的相对高度则随着氧化锆颗粒密度的减小而减小,暗示该子峰可能起因于由于边壁附近层中颗粒的局域重排。氧化锆颗粒系统的χ″v（f）曲线存在一个特征峰,随Γ0的减小,峰值弛豫时间τp从18 s增加到36 s,在高的Γ0范围内,τp近似趋近饱和,低的Γ0范围内,τp近似遵循阿伦尼乌斯关系,随1/Γ0呈现指数增长。并且弛豫时间τp随着颗粒密度的增大而减小,密度较大的颗粒系统达到稳态所需的时间更短。

The spectrum of dynamical responses on packing volume of the granular system composed of spherical zirconium oxide with different particle density under the vertical taps is measured,and the effects of particle density on the spectrum of dynamic response of granular system are studied. The results show that the granular system composed of spherical zirconium oxide particles can reach a reversible and stable state,whose specific volume only depend on the intensity of the taps,when the tapping amplitude Γ is greater than the critical amplitude Γ＊. The dynamic volumetric susceptibility χ~v（ Γ0） of the stable-state of the granular system exist a double-peak structure,the height of the higher peak increases with decreasing particle density,indicating that the peak is due to the largescale rearrangement of particles in the granular system; while the other peak decreases with decreasing particle density,indicating that the peak is caused by the localized rearrangement of particles near the wall. There is a characteristic peak in the χ″v（ f） curve,the the relaxation time τpcorresponding to the peak frequency increases from 18 s to 36 s with the decreasement of Γ0,and τpis nearly saturation in the higher range of Γ0. In the lower range of Γ0,τpfollows an Arrhenius relation,τpincreases exponentially with 1 / Γ0. The relaxation time τpdecreases with increasing particle density. The larger density of granular system is easier to reach the steady state.