Torsional vibration attenuation of a closed-loop engine crankshaft system via the tuned mass damper and nonlinear energy sink under multiple operating conditions

Abstract

In recent years, nonlinear energy sink (NES), as a nonlinear dynamic vibration absorber (NDVA), has been widely studied due to its high robustness and broadband vibration attenuation effectiveness, compared with the traditional linear dynamic vibration absorber (LDVA). In the area of crankshaft torsional vibration reduction, the external excitation of a closed-loop crankshaft model changes with the variation of speed, which puts forward higher requirements for wide-band torsional vibration attenuation. This study attempts to explore the feasibility of NES replacing the traditional linear tuned mass damper (TMD) for engine crankshafts in possible practical engineering application by studying a four-cylinders diesel engine crankshaft. Firstly, a multi-inertias nonlinear closed-loop self-excited coupled oscillation model (M-NCSCO) of crankshaft is established, and the correctness of the model is verified through comparison with those from experiments. Based on this, the crankshaft is coupled with optimal TMD (O-TMD), general NES (G-NES), and optimal NES (O-NES), respectively. An improved Newmark–β method is proposed to solve the nonlinear dynamic model numerically. The effects of NES and TMD on the vibration attenuation behavior of the crankshaft are studied under different engine operating conditions (including power, injection timing, single cylinder flameout, and load). The results show that the vibration attenuation efficiency and robustness of G-NES are 7.90% and 3.47% higher than that of O-TMD when considering the above four typical working conditions comprehensively. After further optimization of G-NES, the vibration reduction efficiency of O-NES is improved by 3.1% compared with G-NES.