研究了垂直振动激发下钨颗粒的动态有效质量˜M (ω)和耗散功率p(ω)随频率ω的依赖关系.实验发现,在给定的振动幅度下,自由表面样品有效质量的实数部分M1(ω)、虚数部分M2(ω)以及耗散功率p(ω)随频率的变化曲线均出现一个尖锐的共振峰.随着在颗粒上表面施加压强的增大, M1(ω), M2(ω)和耗散功率p(ω)曲线的峰值频率向高频移动,且峰值高度也相应增大.进一步研究发现,有效质量实数部分的共振频率fg 随表面压强P的变化满足分段幂律规律,当P较小时,幂指数为0.3,当P较大时,幂指数减小为1/6.颗粒系统的品质因子的倒数1/Q随压强P的变化满足指数衰减规律.%The dependences of the dynamic effective mass ˜M (ω) and power dissipation p(ω) of tungsten particles system on frequencyωare studied under vertical vibration excitation. It is found that there appears a sharp resonance peak in each of spectra of the real part M1(ω), the imaginary part M2(ω) of the effective mass, and the power dissipation for a given vibrating strength. With the increase of the pressure acting on the top surface of the particle, each peak frequency of the M1(ω), M2(ω) and power dissipation moves to higher frequency, and the peak height also increases accordingly. Further study finds that the resonance frequency fg of the real part of the effective mass satisfies piecewise power-law with the change of pressure P acting on the top surface. At low P value, the power exponent is 0.3, and at high P value the power exponent decreases to 1/6. The reciprocal of quality factor of the granular system, 1/Q, decreases exponentially with the change of pressure P .
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