前言 1970年以前,船的振动大部分是由螺旋桨激振力引起。随后采取了螺旋桨安装整流鳍、采用大侧斜桨叶以及改进结构设计法等措施,螺旋桨引起的振动大大减少。但由船舶主机、推进轴系和辅机等回转机械产生的振动仍是设计、制造和安装时必须着重考虑的问题。最近,回转机械由高性能化的要求而向高速化和大型化方面发展,振动条件也日益严 Foreword Before 1970, most of the ship’s vibrations were caused by propeller excitation forces. Subsequent adoption of the propeller installation of the rectifier fins, the use of large side inclined blades and the improvement of structural design and other measures, the propeller-induced vibration is greatly reduced. However, the vibrations generated by the rotating machinery such as the ship’s main engine, propeller shafts and auxiliary machinery are still issues that must be seriously considered in the design, manufacture and installation. Recently, rotary machines have been developed toward higher speeds and larger sizes due to demands for higher performance, and vibration conditions have become increasingly severe