平头塔式起重机整机振动模态及振动响应分析

Analysis on vibration mode and vibration response of flat-top tower crane

平头塔式起重机运行机构的频繁起、制动容易引起整机结构振动,为了探索有效消除这一振动的控制理论和方法,采用Ansys软件建立平头塔式起重机有限元模型,提取整机结构前10阶振动模态的固有频率和振型,分析起升机构、变幅机构和回转机构运动产生的惯性力、离心力和科氏力与整机振动模态的激励关系,最后在有限元模型上模拟起升机构在抓取货物过程中起重臂的振动响应。仿真结果表明:机构运动的惯性力会激励平头塔式起重机在运动平面内的振动模态,回转运动产生的离心力会激励在起重臂铅垂面内的振动模态,科氏力会激励在回转运动切平面内的振动模态,整机结构的振动响应是在不同工况下多个模态的振动响应的叠加。

It is noticed that frequent start and braking of traveling mechanism of flat-top tower crane tend to cause the vibration of the whole crane. To find effective theory and method to eliminate vibration, Ansys software is used to set up finite element model for the crane. With the model, natural frequency and vibration type of the crane in the first 10 vibration modes are obtained, and the excitation relationship among inertia force, centrifugal force and Cariolis force generated during the operation of hoisting mechanism, luffing mechanism and slewing mechanism is analyzed. Furthermore, vibration response of boom at the time of hoisting mechanism grabbing cargo is simulated by using the finite element model. The simulation results show that inertia force of the mechanisms stimulates the vibration mode of the crane in the plane of motion, centrifugal force from slewing motion stimulates the vibration mode in the vertical plane of the boom, and Cariolis force stimulates the vibration mode in the tangent plane of slewing motion. Therefore, vibration response of the entire crane is the superposition of vibration response of multiple modes under different conditions.