The Torsional Vibration Characteristics Analysis Of Crankshaft System Of Marine High-power Reciprocating Compressor

Reciprocating compressor is a kind of widely used power machinery.Its vibration characteristics are related to its life and work efficiency.The vibration of the crankshaft system is an important factor that causes vibration of the whole machine.The vibration of the crankshaft system includes lateral vibration and torsional vibration.For the six-column reciprocating compressors with more support,torsional vibration is the main vibration form of the shafting system.It is easy to generate torsional resonance within the working speed range of the compressor and damage the shaft system and other parts of the machine body.This article combines the Ministry of Industry and Information Technology project ‘Study on vibration and noise control technology of marine high-power reciprocating compressors' to analyze the torsional vibration characteristics of marine high-power reciprocating compressor shafting,which mainly includes the following contents.Firstly,the modal analysis of the high power reciprocating compressor crankshaft system was performed.Set up a lumped parameter model of crankshaft torsional vibration system to solve the natural frequencies and modes of torsional vibration of each mode.At the same time,finite element method was used to establish the finite element model of the crankshaft of the high power reciprocating compressor,and the modal information of each mode was obtained.The modal information of the two models was compared and the results were close,which validates the effectiveness of the two models.Secondly,based on the modal superposition principle,the torsional vibration response of the crankshaft system is solved.The structural characteristics and dynamic characteristics of marine high power reciprocating compressor crankshaft system were analyzed,and the forced excitation analysis of crankshaft system multi-freedom vibration system was completed.Then based on the solution of the natural frequency and normalized vibration mode of the crankshaft system,the response of multi-degree-of-freedom torsional vibration system of the crankshaft system is solved by the modal superposition method,and the contribution of each mode shape to the overall response was analyzed,the result show that the first three orders contribute more.Thirdly,the torsional vibration analysis of the crankshaft system was completed based on the rigid-flexible coupled multibody dynamics theory.A three-dimensional model of the crankshaft system was built and a multi-body dynamic model was established based on the actual coordination relationship.The rigid body is replaced with a crankshaft soft body file containing modal information to complete the rigid-flexible coupling multi-body dynamics modeling of a high-power reciprocating compressor crankshaft system.For the dynamic simulation of the crankshaft system,the dynamic response of the crankshaft system was obtained,and the torsional vibration response at the free end of the crankshaft is extracted,the results show that the torsional vibration response of the crankshaft system meets the safety requirements.Finally,the vibration control was studied based on the lumped parameters and the multi-body dynamics model of rigid-flexible coupling.The sensitivity of the first-order torsional natural frequency to the structural parameters of the shaft was obtained by direct derivation.Based on this sensitivity analysis,targeted dynamic modification of the compressor shafting was performed.Combining the optimal Latin hypercube sampling technology,radial basis neural network fitting technology and genetic algorithm optimization technology,the optimal design of the crankshaft structural dimension parameters was achieved,so as to realize the overall optimization including the torsional vibration performance of the crankshaft system.