BM刀盘裂纹损伤特性及疲劳可靠性研究

utterhead of a tunnel boring machine(TBM),the main weighted part in the process of tunneling,bears loadings in different directions.A fatigue failure of cutterhead would severely affect the construction progress and safety.Therefore,it is of great importance to study the fatigue reliability of its cracks.In this paper,the critical point of the cutterhead was found using the static strength analysis,and we analyzed the dynamic stress characteristics.In addition,the stress intensity factor of cutterhead crack was calculated using the sub model technique,and the crack propagation mechanism and damage characteristics of cutterhead crack were also analyzed.Then,combined with crack fatigue theory,we proposed a fatigue reliability evaluation method based on JC method,and the effects of different factors on the reliability were discussed for different geological conditions.The results show that the crack propagation has open-type and tear-type in the deepest part of the crack tip,but there are three kinds of propagation modes at both ends.As the initial crack depth increases,the fatigue reliability of the cutterhead decreases significantly.The reliability is positively correlated with the crack shape ratio.However,there are no significant relationships between the reliability and depth of the critical crack.