旧曲轴机械性能变化的模拟与动态分析

The Simulation of the Mechanical Properties Change and Dynamic Analysis for the Used Crankshaft

曲轴是柴油发动机的重要组成部分,是最有价值的再制造零件,研究其在役过程中经受疲劳损伤后机械性能降低的动态特征,将是评估其是否可再制造的重要参考。通过降低材料弹性模量来模拟机械性能的降低,在ANSYS14.0有限元软件中直接建立曲轴三维有限元模型,计算其前10阶固有频率和振型;对比分析新旧(机械性能降低后)曲轴模态参数的变化。分析结果表明,机械性能降低后的旧曲轴的固有频率均降低且高阶的变化量较低阶固有频率的变化量要大,但是其相对应的振型却完全没有大的变化。这可能将为通过实测动态性能评估旧曲轴的可再制造提供参考依据。

As an important component of diesel engine,crankshafts are the most valuable remanufacturing parts. The study on the dynamiccharacteristics of the used crankshaft which the mechanical properties change were caused by fatigue cumulative is an important reference for assessing its remanufacturing.In this paper, the decrease of mechanical properties is simulated by reducing the elastic modulus of material. The three-dimensional finite element model of the crankshaft was directly established by using ANSYS14.0 finite element software and then the first ten orders natural frequency and vibration modes were calculated.Finally,the change of modal parameters of the new and the used crankshaft which mechanical properties have been reduced were compared and analyzed. The analysis results are as follows： all of the natural frequencies of used crankshaft reduce and the variable quantity of high order natural frequencies are larger than the low orders＇;but the vibration modes have no more changes,which may provide the reference basis for assessing remanufacture of usedcrankshafts by estimating its dynamic performance.