变压力工况下压裂泵的疲劳失效演化规律研究

Fatigue Failure Evolution of Fracturing Pump under Changing Pressure Condition

页岩气大规模压裂作业中,压裂泵受周期性变化的复杂载荷作用,易发生疲劳失效;现场试验耗费人力物力,数值求解过程繁琐,且均存在一定难度。为此,利用ANSYS和FE-SAFE平台开展研究,以寻找变压力工况下压裂泵的疲劳失效演化规律。选取柱塞和泵头体等6个主要部件,通过建立三维模型、设定边界约束条件和施加工况载荷-压力,揭示不同压力工况下各部件应力、位移状态及疲劳脆弱点位置;求解各部件应力、位移及疲劳寿命随压力变化的规律;绘制变压力工况下各部件和压裂泵整体的疲劳失效演化图谱。研究结果表明:压裂泵主要部件的最大应力、最大位移随压力近似呈线性变化,并得到在最大许用应力范围内各部件满足工况要求,且变压力工况下压裂泵的疲劳脆弱点发生转移。研究结果可为现场压裂安全施工提供技术支撑。

During the process of large-scale fracturing of shale gas,fracturing pump is subjected to periodic complex loads,which is prone to fatigue failure. The manpower and material resources consumed field test and the complicated numerical solution make the issue challenging. ANSYS software and FE-SAFE platform have been used to study the fatigue failure evolution of fracturing pump under changing pressure condition. By establishing the three-dimensional model,setting the boundary constraint conditions and applying the working condition＇s load-pressure,six main components,such as the plunger and the pump head,have been selected to study the stress,strain state and fatigue vulnerability position under different pressure conditions,to reveal relation of stress,strain and the fatigue life of each component with the pressure,to draw the fatigue failure evolution map of various parts and the whole fracturing pump under changing pressure conditions. The results show that the maximum stress and the maximum strain of the main components of the fracturing pump were linearly changing with the pressure. The main components met the requirements of working condition under the maximum allowable stress. The fatigue weak point of the fracturing pump was transferred under changing pressure condition. The results could provide technical support for safe fracturing operation.