| Engine-generator system, the vital component for the electric drive mining dump truck, is the power supply. Its shafting is a multi-degree of freedom vibration system. Considering that the components are elasticity, not absolutely rigid, on high-speed rotation condition, portions of shafting will produce transient rev fluctuation with various magnitudes and phases, which is torsional vibration. Under the uneven torque excitation from the engine and the generator and the excitation frequency near the natural frequency of the system, the torsional vibration will bring resonance. The load from resonance will lead to disaster, such as broken shaft and gear teeth, shortened part life, even endangered the safety of the vehicle. Torsional vibration is one of the major factors for effecting reliability, stability and noise level. It is the focus field studied by researchers.On the working situation, engine-generator system suffers the combined effects of the gas explosion pressure, piston-rod inertia force, electromagnetic parameter and electromechanical coupling excitations. The complex torsional vibration is normal phenomenon. For comprehensively researching the shafting torsional vibration characteristics, it is necessary to analyze the engine-generator system. According to the structural of engine-generator shafting, this article focuses on analyzing the torsional vibration characteristic and routine effected by internal and external incentives with multiple aspects, complex methodologies. The theoretical reference is provided for systems design, optimization, vibration and noise control.In this paper, the research object is the engine-generator system rotating shafting. And torsional vibration is the entrance.First of all, for the shafting torsional vibration problem, the lumped mass model is established, after completely analyzed the structural parameters inside and incentives outside. Thus dynamics differential equation of torsional vibration is derived. The free vibration characteristics is calculated by using the traditional algorithm of the generalized Jacobi eigenvalues. For the nonlinear terms in forced vibrations, the multiple scales method is selected as the vibration characteristics solution to obtain the natural frequency and vibration mode.Secondly, the1D simulation model of the engine-generator system shafting torsional vibration is built with AMESim. Through respectively calculating each component, analyzing the free/forced vibration, shafting torsional vibration spectrum and waterfall figures are plotted to verify the theory solution. Meanwhile the correlation between the stiffness of the parts and vibration characteristics.Thirdly, the torsional vibration test bed is built to simulate shafting torsional vibration characteristics for reality. According to the structural characteristics of torsional vibration, the non-contact method is used with LMS SCADAS acquisition instrument to complete experimental verification. The test procedure is from actual working conditions, including constant speed, speed tracking, variable load measurement. With the analysis of the angular velocity fluctuations, waterfall, harmonic order, order tracking figures, etc., the natural frequency, resonance critical speed, impact of variable load are obtained.Fourthly, besides mentioned above, control method is studied. The major object are the effects of crankshaft torsional damper and dual-mass flywheel damper on the characteristics of shafting torsional vibration and special dumper design. Different methods are used to analyze damping effect of two dumpers which can be the reference for future designs.The theory, simulation, test and control method prove that the calculated characteristics using the model in this paper is coincide with the actual test. The test bed can be the development tool for a series of shafting torsional vibration characteristics research. The Research methods, conclusion and damping measures can be applied to the actual design. |
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