铜微颗粒碰撞阻尼特性

碰撞阻尼在机床、机器人、透平机械、飞机以及运载火箭等领域具有重要的应用价值. 在碰撞阻尼器中加入微颗粒材料, 可以利用颗粒的细化和塑性变形而有效地吸收振动能量, 为碰撞阻尼的研究和发展开辟了一条新途径. 本文讨论了带有中值粒度为50 μm的铜颗粒碰撞阻尼器在96 h内对正弦激励悬臂梁的阻尼减振特性. 研究表明, 在所考察的时间段内, 主系统的响应经历了先上升、再下降和再上升的过程. 这三个阶段的响应对应着铜颗粒微观结构变化的三个阶段. 在初始阶段, 铜颗粒主要表现为弹性变形, 能耗较低, 而钢球的次谐波共振可能将部分能量返回给主系统, 使主系统响应随时间呈现近似线性的上升; 在第二阶段, 当主系统响应增加到一定程度时, 钢球对铜粉的冲击力超出铜颗粒的屈服应力, 铜颗粒发生屈服, 不可逆能耗使主系统的响应震荡下降; 到了第三阶段, 铜颗粒在钢球冲击下发生硬化, 其应变和层错概率上升, 应变能和层错能下降, 主系统的响应再次持续震荡上升. 本文的结果对振动的被动控制以及材料塑性变形机理研究具有参考 意义.关键词：振动控制碰撞阻尼颗粒减振剂微结构分析

Characteristics of micro fine copp er particles impact damping

Impact damping has been widely used in machine tools, robots, turbine machineries, aircrafts, and launch vehicles. Introducing micro fine particles into impact dampers may bring additional irreversible energy loss such as particle size reduction and plastic deformation for the damping, and carve out a new way to control the motion. For this purpose we use copper particles with an average size of 50 μm in ball impact dampers installed on a cantilever subjected to sinusoidal vibration within 96-hour impacting, and test the damping characteristics. We show that the response of the primary system can be divided into three stages, i.e., increasing, then deceasing, and increasing again. This dynamic feature reflects the deformation behaviors of the micro copper particles in different stages. In the first stage, the copper particles may display elastic behavior, and the sub-harmonic vibration of the steel ball may return part of the energy back to the primary system and enhance the response. In the second stage, the copper particle is forced into its yield point and the plastic deformation exhausts the energy and response of the system decline. In the third stage, hardening effect of the copper particles occurs and the response of system increases again. Our results may be significant to passively control the vibrations and material deformation.
Keywords：vibration controlimpact dampersparticles damping agentmicro-structure analysis