压裂泵虚拟试验连杆疲劳性能研究

压裂泵动力端的连杆在交变载荷的作用下会产生疲劳裂纹,随后裂纹迅速扩展,直至连杆疲劳断裂失效。为了探究裂纹产生的位置及裂纹扩展的过程,进行连杆的3种极限工况的有限元静强度分析,结果表明:在连杆大头盖外圆面和螺栓台面的过渡区有应力集中,并且出现最大Mises 应力。连杆的疲劳分析结果表明:靠近连杆大头的连杆杆身部分、连杆大头盖外圆面和螺栓台面的过渡区是连杆疲劳安全系数最小的位置。裂纹的萌生和扩展都是发生在应力集中的区域,因此连杆在这2处区域萌生裂纹的可能性最大。在靠近连杆大头的连杆杆身部分的过渡区进行裂纹扩展模拟计算,分析了连杆的裂纹扩展规律,预测了连杆的疲劳裂纹寿命,结果表明:当裂纹长度为16.9 mm时,连杆的疲劳裂纹寿命约为8.85×10⁴次。

Study on Fatigue Performance of Connecting Rod in Virtual Test of Fracturing Pump

The connecting rod of the dynamic end of the fracturing pump will producefatigue crack under the action of alternating load, and the crack will expand rapidly until the connecting rod fatigue fracture fails. In order to explore the location of the crack and the process of crack propagation, the static strength analysis of the connecting rod under three kinds of limit working conditions was carried out, and there’s maximum Mises stress. The fatigue analysis results of the connecting rod show that the connecting rod body part near the connecting rod big end, the transition area of the connecting rod big end cap, and the bolt table are the positions with the smallest fatigue safety factor of the connecting rod. Both the initiation and propagation of cracks occur in the regions where the stress is concentrated, so the connecting rod is most likely to initiate cracks in these two regions. In the transition zone near the big end of the connecting rod, the crack propagation law was analyzed and the fatigue crack life of the connecting rod was predicted.The results show that the fatigue crack life of the connecting rod is about 8.85 × 10⁴ times when the crack length is 16.9 mm.