Torsional Vibration Analysis Of 8M80 Symmetrical Full Balance High Speed Crankshaft

Reciprocating compressors are widely used in the petroleum and chemical industries.As the core component of a reciprocating compressor,the crankshaft,is subject to complex periodic load changes during operation,which is prone to torsional resonance and lead to fracture and damage of the crankshaft.Solving these problems is the key to the overall design of the compressor.Especially with the expansion of the company's production capacity,reciprocating compressor technology is rapidly developing towards large,multi-row,high-speed directions,and the technical requirements for crankshafts are becoming higher and higher.In the design process of large,multi-row,high-speed reciprocating compressors,torsional vibration analysis and structural optimization of the crankshaft have important practical value.This article takes the 8M80 symmetrical full-balance high-speed reciprocating compressor crankshaft as the research object.Based on finite element theory,The ANSYS Workbench software was used to analyze the torsional vibration.Firstly,the crankshaft is statically analyzed by applying a single load and a load in the form of a load step,and the crankshaft is checked for strength.The results show that the load applied in the form of a load step file is more in line with the actual operating conditions of the crankshaft.Perform a modal analysis on the crankshaft to obtain the first ten natural frequencies and mode shapes of the crankshaft and compare the results of the modal analysis.The order of the torsional vibration of the crankshaft and the multiples of the fundamental frequency are determined to provide a theoretical basis for dynamic response analysis.The modal superposition method is used to analyze the harmonic response of the crankshaft.According to the analysis results,the degree of influence of simple harmonic load on crankshaft resonance is calculated.Studies have shown that torsional resonance of the crankshaft occurs within the rated speed range,and no bending and lateral vibration will occur;The dynamic analysis of the crankshaft of a large reciprocating compressor only needs to consider the natural frequency of thefirst-order torsional vibration.Based on torsional vibration analysis,the crankshaft structure is optimized.Based on Taguchi design method,Minitab software was used to screen multiple crankshaft structural design variables.Three design variables with significant effects on the strength of the crankshaft and torsional angular displacement are obtained;Based on the Box-Behnken experimental design,Minitab software was used to optimize the optimization goals of the strength and vibration performance of the crankshaft to optimize the design variables with significant impact.The analysis results show that the cyclic peak stress and free end torsional angular displacement experienced by the optimized crankshaft have decreased by 23.25% and 25.36%,respectively,compared to the crankshaft before the optimization.The research results show that on the basis of torsional vibration analysis,The Taguchi design method and the Box-Behnken test design can effectively reduce the peak stress and torsional angular displacement of the crankshaft during operation.Therefore,the optimization purpose of improving the strength of the crankshaft and improving the vibration performance of the crankshaft is achieved.The research results provide a certain reference for the design and optimization of large reciprocating compressors.