基于灰色模型的电动助力车车架耐振性试验寿命预测

Fatigue life-span prediction of the frame of electrical power assisted cycles in vibration test based on grey model

选取了4款踏板式电动助力车车架,每款10个试件,采用JS-49整车振动试验机对每个试件进行耐振性测试,获取每个试件断裂时的振动循环次数。建立了各款车架的有限元振动分析模型,对振动试验进行仿真,提取了各款车架危险位置单元的Von Mises应力峰值,每款车架对应一个应力水平。将疲劳应力与振动循环次数的关系看作一个灰色系统,运用灰色系统方法建立了GM(1,1)模型,并求解了灰色系统模型的微分方程,得到了车架在振动试验中的疲劳寿命预测模型。为了对该模型的效果进行检验,另外选取了3款同类车架进行相同条件下的耐振性测试,每款车架6个试件。通过与试验结果进行对比,发现灰色模型预测的平均相对误差为4.08%,且相对于多项式拟合更能反映真实的应力-寿命的变化趋势。结果表明,可用灰色模型对此类产品的设计进行指导。

On JS-49 vehicle vibration test machine,4 types of electrical power assisted pedal cycle frames were chosen to test their vibration durability.10 specimens for each type were tested.A finite element model was then established to simulate the vibration test process of each type of frames,then the peak of Von Mises stress was extracted from the cracked element.Each type of frame corresponds to a stress level.The relationship between the fatigue stress and vibration cycles was considered as a grey system.The GM（1,1） model was built by using the method corresponding to grey system,then the differential equation of GM（1,1） was solved to obtain the critical parameters of the fatigue life-span prediction model.The error checking of the prediction model indicates that the average relative error is 4.08%.The model could be used to guide the design of relevant products.