冲击荷载下颗粒破碎分维变化及能量耗散研究

Fractal Dimension Change of Particle Fragmentation and Energy Dissipation in Impact Test

颗粒受冲击荷载,发生破碎现象,改变颗粒粒径分布,影响颗粒力学性能。随着颗粒破碎程度的增加,最终颗粒分布会趋向自相似分布,称为分形分布。为研究冲击对颗粒破碎粒度分布的影响,通过试验,得到了炉渣颗粒和大理岩颗粒受冲击破碎的颗粒分布曲线及分形维数的变化规律。研究发现,颗粒受冲击破碎后,不会无限制的破碎;粒度分布符合分形模型;分形维数随破碎程度加深逐渐增大,但存在极限。最终的分形维数可以与颗粒力学特性建立联系以推导颗粒破碎能耗和颗粒弹性应变能。考虑颗粒间不同的接触类型,忽略颗粒间摩擦,根据断裂力学理论,建立的颗粒破碎的能量平衡方程可以很好地描述颗粒破碎过程中能量转化的规律。

Particles will be crushed with the changes of the particle size distribution and the mechanical properties when they are subjected to impact load.With the increase of the degree of particle crushing,the final particle distribution will tend to self-similar distribution,which is called fractal distribution.The tests were carried out for clinker and marble particles in order to study the effect of impact load on particle size distribution,the PSD curves and the variation law of fractal dimension of the two kinds of particles are obtained when they are subjected to impact load.The results show that particles will not be crushed without limitation,the PSD curves consistent with the fractal model,the fractal dimensions increase with the degree of particles crushed which exist a limit value.The expression of energy dissipation and the strain energy of particle crushing are derived by contacting the final fractal dimension and mechanical properties.According to the theory of fracture mechanics,the energy balance equation of particle crushing can be well described by the law of energy conversion in the process by ignoring the friction between particles.