基于构件S-N曲线的波纹管速度外压耦合加载下疲劳寿命研究

真空灭弧室用波纹管服役工况复杂，采用传统的理论计算方法和试验手段难以准确预测其疲劳寿命，一定程度上制约波纹管的设计与选用。本文利用数字图像相关技术，基于拉伸试验、疲劳试验，精细化获得了波纹管构件的S-N曲线，基于ANSYS有限元分析软件，建立波纹管弹塑性变形有限元模型，通过XTDIC验证了模型的准确性，结合nCode DesignLife对波纹管疲劳寿命进行了预测，并验证其准确性。研究了关键工艺参数(压力、位移、速度)对波纹管波峰、波谷等关键特征区域应力、应变和疲劳寿命的分布演变规律。研究表明：波纹管在只施加外压的工况下，波峰内壁处更容易产生疲劳损伤，位移载荷对波纹管应力应变分布影响更为显著，位移越大，波纹管更容易产生应力集中。在加载位移不变时，速度越大，波纹管等效应力越大，此时耦合0.2 MPa外压，抵消部分应力集中。在0.2 MPa外压下，当压缩速度由0.5 m/s增加到4 m/s，最大等效应力由378.89 MPa增加到424.27 MPa，疲劳寿命由49 540次减小到3 064次。

Fatigue Life Research of Bellows under Coupled Loading of Velocity and External Pressure Based on S-N Curve of Components

The service conditions of bellows for vacuum interrupters are complex, and it is difficult to accurately predict their fatigue life by traditional theoretical calculation methods and experimental methods, which restricts the design and selection of bellows to a certain extent. In this paper, using digital image correlation (DIC) technology, based on tensile experiments and fatigue experiments, the SN curve of the bellows member was refined and obtained. Based on the ANSYS finite element analysis software, the finite element model of the elastic-plastic deformation of the bellows was established. The accuracy of the model is combined with nCode DesignLife to predict the fatigue life of bellows and verify its accuracy. The distribution evolution law of key process parameters (pressure, displacement, speed) on the stress, strain and fatigue life of the bellows in key characteristic regions such as wave crests and wave troughs is studied. The research shows that under the condition that only external pressure is applied to the bellows, fatigue damage is more likely to occur on the inner wall of the wave crest, and the displacement load has a more significant influence on the stress-strain distribution of the bellows. When the loading displacement is constant, the greater the speed, the greater the equivalent stress of the bellows. At this time, the external pressure of 0.2 MPa is coupled to offset part of the stress concentration. Under the external pressure of 0.2 MPa, when the compression speed increases from 0.5 m/s to 4 m/s, the maximum equivalent stress increases from 378.89 MPa to 424.27 MPa, and the fatigue life decreases from 49 540 cycles to 3 064 cycles.