Failure analysis and optimization of elastic coupling tear for a diesel engine

SHI Shengwen; LIU Jie; WANG Huihui; ZHANG Zhongye; XU Kepeng

doi:10.19471/j.cnki.1673-6397.2025.06.013

Abstract：To address the frequent tearing failure of the rubber body of the elastic coupling at the flywheel end during the bench test of a diesel engine,torsional vibration tests of the shafting system and temperature rise tests of the rubber body of the elastic coupling are carried out to analyze the failure of the elastic coupling.Based on the AVL Excite Designer software,a 1D equivalent simplified model of the bench shafting system is established,and torsional vibration simulation analysis is conducted.An optimization method is adopted by increasing the moment of inertia between the elastomer at the dynamometer end and the universal joint of the cardan shaft,and the effectiveness is verified through simulation analysis and bench tests.The results show that resonance occurs between the first-order torsional vibration frequency of the shafting system and the second-order excitation frequency of the engine,leading to excessive torsional angle vibration of the rubber body of the elastic coupling,which causes torsional fatigue tearing and overheating melting of the rubber body,and finally results in the failure of the rubber body.Because the moment of inertia of dynamometer is greater than that of engine,the relative torsion angle of the rubber body of the elastic coupling at the flywheel end is greater than that at the dynamometer end,so the dissipated power of the rubber body of the elastic coupling at the flywheel end is greater than that at the dynamometer end,which leads to the elastic coupling at the flywheel end being more prone to failure.By increasing the moment of inertia between the elastomer at the dynamometer end and the universal joint of the cardan shaft,the first-order torsional vibration resonance frequency of the shafting system can be shifted away from the common speed range of the engine.Meanwhile,the dissipated power of the rubber body of the elastic coupling at the flywheel end is reduced by 33％,which prolongs the service life of the coupling rubber body and effectively solves the problem of frequent tearing of the rubber body of the elastic coupling at the flywheel end.