Thermal-mechanical creep and fracture crack growth of a near-α titanium alloy
A multiscale fatigue crack growth model is used to analyze the thermal-mechanical effects in a near-α Titanium alloy material under the non-additive effects of creep and cyclic loading.The effects are necessarily coupled when thermodynamic non-equilibrium and material non-homogeneity are accounted for since scale transition is the rule rather than the exception.This has been demonstrated for the micro-macro creep and fatigue crack growth in steel under thermal-mechanical disturbance.Three normalized generic parameters are used to reflect the loading,material and geometry.They are time dependent and referred to as σ*(=σo/σ∞),μ* (=μmicro/μmacro) and d* (=d/do).All physical properties change with time.Depicted is a near-α titanium alloy TA12 (Ti-5.5Al-4Sn-2Zr-1Mo-0.25Si-1Nd) that is used for airplane engine operating around to 550℃.A time span of 10 years and flying time of 60000 hours are used in the computation with a temperature profile that rises from 300℃ to 550℃ and then decrease to 300℃.Symmetry is advocated for simplicity.Under these conditions,an initial crack 2.6mm long became unstable after 7.5 yrs,while a shorter crack 2.2mm long lasted 9.4 yrs.These results are preliminary and they will alter according to the temperature profile and the cyclic loading.Moreover,crack growth may not be limited to the micro-macro scale.Smaller crack sizes may be involved during the initial stage where creep may dominate.These and other possible cases will be examined in the future.
multiscale thermal creep and fatigue crack growth Micro/Macro
K.K.Tang
Key Laboratory of Pressure Systems and Safety,Ministry of Education,School of Mechanical and Power Engineering,East China University of Science and Technology,Shanghai 200237,China
国际会议
International Conference on Airworthiness & Fatigue -7th ICSAELS Series Conference(大飞机安全性能与疲劳国际会议)
北京
英文
135-143
2013-03-24（万方平台首次上网日期，不代表论文的发表时间）