低速柴油机推进轴系频域稳态扭转振动分析

以载重10 000 t低速柴油机推进轴系为研究对象，创建其当量系统模型。基于系统矩阵法对推进轴系进行自由振动分析，求得扭转振动固有频率和振型。研究柴油机在全转速下的气体和往复惯性激励力矩，针对推进轴系在柴油机和螺旋桨共同激励下的频域稳态扭转振动响应特性进行计算，求得推进轴系扭转振动的主谐次、共振转速点和推进轴系各部件的应力值。结果表明，推进轴系在低阶频率振动时气缸和中间轴振幅较大，推进轴系应力远小于材料的屈服强度，船舶能够安全稳定航行，同时为推进轴系时域瞬态扭转振动研究打下基础。

Analysis of Torsional Vibration in Frequency Domain Steady State of Propulsion Shafting of Low-Speed Diesel Engine

The propulsion shafting of 10 000 t low-speed diesel engine is taken as the research object to establish its equivalent system model. Based on the system matrix method, the free vibration of propulsion shafting is analyzed, and the natural frequency and vibration mode of torsional vibration are obtained. The gas excitation torque and reciprocating inertia excitation torque of diesel engine at full speed are studied, the response characteristics of torsional vibration in frequency domain steady state of propulsion shafting under the combined excitation of diesel engine and propeller are calculated, and the principle harmonic order and resonance speed point of torsional vibration of propulsion shafting and the stress values of each component of propulsion shafting are obtained. The results show that the vibration amplitude of cylinder and intermediate shaft is larger and the stress of propulsion shafting is much smaller than the yield strength of the material when the propulsion shafting vibrates at low order frequency, so the ship can sail safely and stably. The results also lay a foundation for the research of torsional vibration in time domain transient state of propulsion shafting.