某船用主机中间支架振动特性分析

Analysis of vibration characteristics of a marine mainframe

针对某船用主机中间支架振动强烈危及船舶主动力系统安全运行的情况,文章应用有限元软件ANSYS对设备进行逆向仿真分析。首先根据装配图纸和实际设备,建立了有限元模型,然后采用模态叠加法得到了减振系统的前六阶固有频率及振型,运用谐响应分析法计算了中间支架的作用点动刚度。分析发现当主机转速在1 000 r/min左右时发生共振,中间支架的水平动刚度接近最小值,与模态阻尼比的大小成正比,导致中间支架水平方向剧烈摆动。

In view of the fact that the vibration of the intermediate support of a ship’s main engine strongly jeopardizes the safe operation of the ship’s main power system,the article uses the finite element software ANSYS to carry out the reverse simulation analysis of the equipment. Firstly,according to the assembly drawings and actual equipment,the finite element model is established. Then the first six natural frequencies and vibration modes of the damping system are obtained by the modal superposition method. The harmonic response of the intermediate bracket is calculated by the harmonic response analysis method. The analysis found that when the main engine speed is about 1 000 r/min,the horizontal dynamic stiffness of the intermediate bracket is close to the minimum value,which is proportional to the magnitude of the modal damping ratio,which causes the intermediate bracket to swing vigorously in the horizontal direction.