Fatigue fracture failure investigation of splitter in engine intermediary casing

The splitter fairing welded by sheet metal of stainless steel was installed in the aircraft engine intermediate case. Under operation load, cracks initiated and propagated along the welded seam in the splitter fairing, which seriously threatens the safe operation of the engine. In this work the cracks in the splitter fairing were detected, and the morphological characteristics of the crack surface were analyzed in detail using a scanning electron microscope (SEM). The cracks in the splitter fairing were initiated from the edge of the weld seam, which is the assembly slot for the splitter. The microstructure analysis of the crack initiation zone confirmed that the microstructure defects such as false welding and oxidation are the direct causes of the fatigue failure of the splitter. Mechanical analysis of splitter fairing under random vibration using the finite element method was performed to confirm that the crack initiated at the stress concentration zone during random vibration load.