单轴拉伸状态下橡胶隔振器的疲劳寿命预测研究

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。

The investigation of rubber isolator’s fatigue life prediction under uniaxial tension load

In order to predict the fatigue life of rubber isolator, the prediction model is proposed on the basis of experimental data by using the dumbbell-shaped rubber sample, thereby coming up with a corresponding prediction scheme. The fatigue tension experiment of the dumbbell-shaped rubber sample is devised, and then the experimental data is observed. Additionally, the prediction model in the form of power function is fitted by the least square method. Thereafter, three common evaluation parameters, i.e. Logarithmic principal strain, Cauchy principal stress and strain energy density, for fatigue life are computed by the finite element method. Lastly, a comparison is made between the prediction and experimental data. It is concluded that all three parameters can be effectively fitted by that prediction model in the same power function form when the fatigue failure criterion declined to the 25 percent of stiffness. Specifically, the prediction value of logarithmic principal strain closes to the observation; likewise, the prediction magnitude of principal strain density is approximately double of the observation; and the reliability coefficient of fatigue life for Cauchy principal stress is approaching to 5. In addition, the shape of all three fitting curves is similar.