单轴拉伸状态下橡胶隔振器的疲劳寿命预测研究

Investigation on rubber isolator's fatigue life prediction under uniaxial tensile load

针对橡胶隔振器疲劳寿命预测问题,基于哑铃型橡胶材料试片的疲劳寿命试验数据,建立橡胶隔振器的疲劳寿命预测模型,进而提出橡胶隔振器疲劳寿命预测的研究方案。设计了一哑铃型橡胶试片进行拉伸疲劳试验,实测其疲劳寿命数据并以最小二乘法拟合了该试片疲劳寿命的幂函数预测模型。再通过有限元方法计算了橡胶隔振器的三种常见的疲劳寿命评价参数:对数主应变、柯西主应力和应变能密度,最后将橡胶隔振器的疲劳寿命预测值与实测值进行比对。结果发现:当疲劳失效标准静为刚度降级25%时,三种疲劳寿命评价参数均能较好地拟合成幂函数疲劳寿命预测模型,对数主应变的预测值较为接近实测值、应变能密度参数的预测值约为实测值2倍左右、柯西主应力预测寿命的可靠性验证系数均接近5,且三种疲劳损伤评价参数的疲劳寿命拟合曲线形状均较为相似。

In order to predict the fatigue life of rubber isolator,a prediction model was proposed on the basis of experimental data by using dumbbell-shaped rubber samples,thereby coming up with a corresponding prediction scheme. The fatigue tension experiment of a dumbbell-shaped rubber sample was devised,and the experimental data were observed.The prediction model in the form of a power function was fitted with the least square method.Thereafter,three common evaluation parameters including logarithmic principal strain,Cauchy principal stress and strain energy density for fatigue life were computed by using the finite element method.A comparison was made between the predicted and experimental data.It was concluded that all the three parameters can be effectively fitted with the prediction model in the same power function form when the fatigue failure standardy static stiffness drops 25 percent;specifically,the prediction value of logarithmic principal strain is close to the observation;the prediction magnitude of principal strain density is approximately double of the observation;and the reliability verification coefficient of the predicted fatigue life according to Cauchy principal stress approaches 5;the shapes of all the three fitted curves are similar.