The high low cycle complex fatigue behaviours of Ti alloy TC11 were researched systematically at room and elevated temperatures.At the same time

the effects of complex stress ratio m

test temperature and prestress overload for SEN specimen on complex fatigue life N fL were taken into consideration.The work comes to the conclusion that:The complex fatigue life decreases obviously with m increased

especially when m =35%

the Nfl decreases more than 10 times

and there occurs a knee on the m —log NfL curve near m =10%.The complex fatigue of the alloy TC11 is very sensitive to test temperature under the same m ratio and LCF stress

as test temperature rises from room temperature to 150℃

the complex fatigue life NfL drops by 66% under m =10% and σ max =945MPa.If the temperature comes up continuously to 300℃

its fatigue life approaches to zero.In addition

a model of the accumulative damage for complex cyclic fatigue is formulated as follows: 1/NfL =1/N L+n/Nf .