Estimation of thermo-mechanical fatigue crack growth using an accumulative approach based on isothermal test data

Fatigue–oxidation–creep damage model under axial-torsional thermo-mechanical loading

“…For example, the failure life under MIPTOP 90 loading (1063 cycles) is more than two times of that under MIPTOP 180 loading (457cycles). Under MIPTOP 180 loading, the compressive stress corresponding high temperature cannot induce creep damage (Kraemer et al, 2017;Li et al, 2018;Miller et al, 1992), thus the creep damage can be negligible on this loading condition, which can also be proved by the transgranular fracture under MIPTOP 180 loading, as shown in Figure 6. The situation is the same under MIPTOP 90 loading, that is, the creep damage can also be ignored under MIPTOP 90 loading.…”

“…where A is the oxidation rate constant, and Át is the time increment of ith portion. Moreover, the oxidation rate constant A is following the Arrhenius equation (Kraemer et al, 2017;Wu and Zhang, 2016;Zhao et al, 2010), that is, A can be determined by…”

“…The material constants b 1 , b 2 , b 3 , b 4 , and b 5 can be determined by fitting the data of creep tests at different temperatures. At elevated temperature, the compressive stress cannot induce the creep damage (Kraemer et al, 2017;Li et al, 2018;Miller et al, 1992). Based on the above creep damage mechanism, the equivalent creep stress c i can be calculated by the following criterion…”

“…The creep damage can be induced by the tensile stress at high temperature, and be increased by the shear stress at the same time (Li et al, 2018). The compressive stress corresponding high temperature cannot contribute to the creep damage under TMF loading (Kraemer et al, 2017;Miller et al, 1992). The oxidation occurred when the material is exposed to elevated temperature, and the oxidation damage is dependent on temperature, time, and stress (Vo¨se et al, 2013).…”

“…The model has been employed for the life prediction of the engineering components under TMF loading (Abu et al, 2014;Escola´n et al, 2017;Kang et al, 2007;Minichmayr et al, 2008). Furthermore, the fracture mechanics parameters, including cyclic stress intensity factor (Kraemer et al, 2017), the cyclic Jintegral (Christ et al, 2003;Esmaeilzadeh et al, 2017), and the cyclic crack-tip opening displacement (Seifert and Riedel, 2010;, were also investigated to estimate the crack growth rate under TMF loading. In the above investigations, the time independent and dependent damages (crack growth rates) are linearly combined during the calculation process.…”