Study On The Properties Of Fatigue Crack Propagation For High-power Rotary Marine Propeller Based On XFEM

The propeller is the key component of propulsion system in ship and marine equipment,and Fatigue fracture is the main failure mode.Therefore,study on the influence factors and properties of fatigue crack propagation for high-power rotary marine propeller make a good sense of improving our country marine power.In this paper,a certain type of high-power rotary propeller was chosen as the research object,and the stress intensity factors of crack tip were calculated by extended finite element method(XFEM).The relationship between stress intensity factor crack growth rate was deduced according to experimental test data.Then the high-power propeller blade fatigue crack propagation numerical simulation model was built based on the linear elastic fracture theory,and the analysis of crack propagation included three parts: different load condition,different crack initial size and different crack initial shape(surface crack,corner crack and immerged crack).According to the simulation results and data analysis,the larger the size of the crack initial size and load are,the stress intensity factors become much bigger and the fatigue cracks grow much faster.The propagation path of three kinds of initial crack types are mostly irregular oval and crack growth more quickly on the direction towards propeller pressure surface.Simulation results show that the crack extension texture map has a good fit with propeller actual fracture surface texture.Different characteristic parameters of surface roughness have been analyzed by using 2D numerical model which contain profile depth,profile width and profile interval.When the width and interval rises,the phenomenon of stress concentration fades,the fatigue cracks grow slower;and when profile width and bottom curvature rises,the stress concentration becomes more obvious,the fatigue cracks grow much faster.Research work on optimization of high-power rotary propeller blade designing and processing technology can be a good guidance to improve performance and reliability.