循环冲击条件下磁铁矿石损伤特征研究

Study on Damage Characteristics of Magnetite Ore Subjected to Cyclic Impact

为研究磁铁矿石循环载荷条件下的损伤发展规律,采用落锤冲击试验装置,对磁铁矿石进行了不同高度的循环冲击试验,分析了损伤因子随冲击次数和矿石吸收能的变化特征。结果表明:冲击高度较小时,前几次冲击波速与损伤因子无明显变化,随着循环冲击次数的增加,波速缓慢减小,损伤因子缓慢增加,试件发生宏观破坏时,其值发生急剧变化;随着冲击高度的增加,波速逐渐降低,试件累积吸收能和冲击次数显著减少,损伤因子增长速率明显增大;研究结果将磁铁矿石循环冲击损伤至完全断裂过程划分为三个阶段,即初始损伤阶段、加速损伤阶段、断裂阶段,存在使磁铁矿石发生一次性冲击完全断裂的最低能量。研究结果为矿山磁铁矿石破碎节能降耗提供理论依据。

In order to study the damage development law of magnetite under the condition of cyclic loading,the drop hammer impact test device was used to conduct cyclic impact tests at different heights on the magnetite,and the change characteristics of the damage factor with the number of impacts and the absorbed energy of the ore were analyzed.The results showed that when the impact height is small,the first few shock wave velocities and damage factors do not change significantly.With the increase of the number of cyclic impact,the wave velocity slowly decreases,and the damage factor slowly increases.When the specimen undergoes macroscopic damage,the value of damage factor changes dramatically.With the increase of the impact height,the wave velocity gradually decreases,the cumulative absorbed energy of the specimen and the number of impacts are significantly reduced,and the growth rate of the damage factor significantly increased.The results of the study divides the process of cyclic impact damage to complete fracture of the magnetite into three stages,that is the initial damage stage,accelerated damage stage,and fracture stage.There is the lowest energy that can completely break the magnetite ore in a one-time impact.The research results provide a theoretical basis for energy saving and consumption reduction of the magnetite ore crushing.