基于断裂力学的高压共轨燃油系统可靠性设计

Reliability Design of High Pressure Common Rail Fuel System Based on Fracture Mechanics

共轨系统喷射压力的提高,对产品可靠性设计提出严峻挑战。如高压油道表面初始微裂纹、材料内部夹杂物等缺陷都会对产品可靠性产生重要影响。断裂力学是研究裂纹萌生及其扩展规律的科学,其揭示了材料特性、结构设计及加工工艺三者之间的内在联系。以某双油道喷油器体为例,采用断裂力学研究其在交变压力载荷作用下裂纹扩展的路径。研究结果与实际裂纹断口形貌检测结果一致。在高压共轨燃油系统的开发过程中,可应用断裂力学理论对结构应力、微裂纹大小及应力强度因子三者进行优化匹配。这对结构设计优化、加工工艺控制及关键零部件材料选择具有重要指导意义。

With the increase of a injection pressure of a common rail (CR) fuel system, the reliability design of the CR fuel system is faced a severe challenge. For example, initial micro-cracks on fuel pipe surface or impurity in material has an important impact on the reliability of the system. Fracture mechanics is a science of studying the law of crack initiation and propagation. It reveals in detail the internal relationship among material properties, structural design and processing technology. Taking a double-channel injector as an example, the crack propagation path of the injector under alternating pressure was simulated based on the fracture mechanics theory. The simulation results are consistent with the results of actual crack fracture morphology test. During the development of the CR fuel system with high injection pressure, the application of the fracture mechanics theory to optimizing the matching of structural stress, micro-crack size and stress intensity factor can play an important guiding role in structural design optimization, process control and material selection.