Attenuation Law of Stress Wave in Granular Particles
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摘要: 脆性散体颗粒在受到冲击加载时，会对应力波传播产生显著的衰减作用。基于离散元颗粒流软件PFC3D建立了散体颗粒模型，通过不同加载速率下的数值模拟，研究应力波在散体颗粒中的传播规律和影响因素。结果表明：在冲击加载下，散体颗粒中传播的应力波峰值整体呈指数型衰减，随着传播距离的增大，应力波衰减程度逐渐减小，颗粒破碎程度也逐渐减小；应力波在散体颗粒中传播时会发生显著的波形弥散，并且应力波波长越短，传播过程中的衰减越大；应力波衰减的率相关性本质上是由散体颗粒的冲击破碎引起的，加载速度越大，颗粒破坏程度越大，应力波的衰减程度越大，而在颗粒不破碎的情况下，加载速度增大时，应力波的衰减程度变化不明显。Abstract: Brittle loose particles exhibit very complex mechanical behavior during the crushing process and have a significant attenuation effect on the stress wave propagation. In order to explore the attenuation law, this paper builds a brittle loose particle model based on the discrete element software PFC3D, and studies the attenuation of stress wave on the microscopic scale. The results show that: under shock loading, the peak value of the stress wave propagating in the granular particles decays exponentially. As the propagation distance increases, the degree of stress wave attenuation gradually decreases, and the degree of particle fragmentation also decreases. Stress wave propagation in granular particles will cause significant wave dispersion, and the shorter the wavelength of the stress wave, the greater the attenuation during propagation. The rate dependence of the stress wave attenuation is essentially caused by the impact fragmentation of the granular particles. The faster the loading speed, the greater degree of particle damage, and the greater the attenuation of stress wave. When the particle is not broken, the degree of attenuation does not change significantly with the increase of the loading velocity.
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Key words:
- brittle particles /
- discrete element model /
- degree of fracture /
- stress wave /
- attenuation law
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图 5 不同直径的测量球对应力波衰减的影响
Figure 5. Effect of measuring ball diameter on the attenuationof stress waves
图 6 应力波衰减规律及颗粒破碎
Figure 6. Attenuation law of the stress wave and the image of particle fragmentation
图 7 不同区域拟合曲线无量纲传播距离
Figure 7. Dimensionless propagation distance of fitted curves in different regions
图 8 应力波在颗粒破碎/不破碎时的衰减规律
Figure 8. Attenuation laws of stress wave when particles are broken/unbroken
图 9 颗粒破碎程度随衰减因子β的变化曲线
Figure 9. Degree of particle fragmentation with respect to the attenuation factor β
图 11 不同脉宽的应力波峰值拟合曲线
Figure 11. Curves of stress wave peaks with different pulse widths
图 12 不同加载速度下可破碎颗粒的峰值应力拟合曲线
Figure 12. Peak stress fitting curves of the crushable particlesat different loading velocities
图 13 不同加载速度下不可破碎颗粒的峰值应力拟合曲线
Figure 13. Peak stress fitting curves of the uncrushable particlesat different loading velocities
图 14 衰减因子、黏结键破碎比与加载速度的关系
Figure 14. Relationship between attenuation factor, bond breaking ratio and loading velocity
表 1 Flat-Joint模型微观参数
Table 1. Micro-parameters of the Flat-Joint model
Model Emod/GPa Fj-Kn/GPa Fj-Ks/GPa Fj-Coh/GPa Fj-Ten/GPa Damp Flat-Joint 50 5.25 × 105 9.37 × 105 0.2 0.05 0.15 
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