Superharmonic nonlinear lateral vibrations of a segmented driveline incorporating a tuned damper excited by non-constant velocity joints

摘要

Linear vibration measurement and analysis techniques have appeared to besufficient with most vibration problems. This is partially due to the lack of properidentification of physical nonlinear dynamic responses. Therefore, as an example, avehicle driveshaft exhibits a nonlinear super harmonic jump due to nonconstant velocity,NCV, joint excitation. Previously documented measurements or analytical predictionsof vehicle driveshaft systems do not indicate nonlinear jump as a typical vibration mode.The nonlinear jump was both measured on a driveshaft test rig and simulated with acorrelated model reproduced the jump. Subsequent development of the appliedmoments and simplified equations of motion provided the basis for nonlinear analysis.The nonlinear analyses included bifurcation, Poincare, Lyapunov Exponent, andidentification of multiple solutions.Previous analytical models of driveshafts incorporating NCV joints are typicallysimple lumped parameter models. Complexity of models produce significantprocessing costs to completing significant analysis, and therefore large DOF systems incorporating significant flexibility are not analyzed. Therefore, a generalized methodfor creating simplified equations of motion while retaining integrity of the base systemwas developed. This method includes modal coupling, modal modification, and modaltruncation techniques applied with nonlinear constraint conditions. Correlation ofresonances and simulation results to operating results were accomplished.Previous NCV joint analyses address only the torsional degree of freedom.Limited background on lateral excitations and vibrations exist, and primarily focus onfriction in the NCV joint or significant applied load. Therefore, the secondary momentwas developed from the NCV joint excitation for application to the driveshaft system.This derivation provides detailed understanding of the vibration harmonic excitationsdue to NCV joints operating at misalignment angles.The model provides a basis for completing nonlinear analysis studying thesystem in more detail. Bifurcation analysis identified ranges of misalignment angles andspeeds that produced nonlinear responses. Lyapunov Exponent analysis identified thatthese ranges were chaotic in nature. In addition, these analyses isolated the nonlinearresponse to the addition of the ITD nonlinear stiffness.In summary, the system and analysis show how an ITD installed to attenuateunwanted vibrations can cause other objectionable nonlinear response characteristics.