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通过对柴油机曲柄 (曲轴 )连杆机构作运动和受力分析 ,将其受力简化为气体膨胀的瞬间作用力和柴油机运转的惯性力 ,且均假设为集中荷载。因此曲轴运转的力学模型也可简化为 :气体作用力为转子周期性脉冲力 ;惯性力为转子—轴承系统的力。这两个力学模型都存在非线性振动 ,且在一定条件下产生混沌现象 ,这从理论上解释了柴油机曲轴的运转能产生非线性振动和混沌。同时本文还应用功率谱法来研究混沌性态。在实例分析中 ,我们通过对 8NVD2U 4 8A柴油机主轴承对应的机体上布采样点 ,对表面振动信号进行采样且对采样进行功率谱分析 ,其结果说明上述结论在理论上是正确的。这一结论也为柴油机曲轴和主轴承的故障诊断提供了理论基础
Through the analysis of the motion and force of diesel engine crankshaft (Crank) connecting rod mechanism, its force is reduced to the instantaneous force of gas expansion and the inertial force of diesel engine operation, and both are assumed to be concentrated load. Therefore, the mechanical model of crankshaft operation can also be simplified as follows: the gas force is the periodic pulse force of the rotor; and the inertial force is the force of the rotor-bearing system. Both of these mechanical models have nonlinear vibration and produce chaos under certain conditions. This theoretically explains that the operation of a diesel engine crankshaft can generate nonlinear vibration and chaos. At the same time, this paper also applies the power spectrum method to study the chaotic behavior. In the case study, we sampled the surface vibration signal from the corresponding sampling points on the body of 8NVD2U 4 8A diesel main bearing and analyzed the power spectrum of the sample. The result shows that the above conclusion is theoretically correct. This conclusion also provides a theoretical basis for the fault diagnosis of diesel crankshaft and main bearing