PSI - Issue 28

A. Vshivkov et al. / Procedia Structural Integrity 28 (2020) 1839–1845 Author name / Structural Integrity Procedia 00 (2019) 000–000

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3. Results A two series of samples was subject to uniaxial and biaxial loadings to record the crack length and the heat flux. The crack propagation rate was 10e-7 – 10e-4 m/cycle. The heat flux sensor enables to measure the integral heat flux. The fatigue crack advanced according to Paris’ law (see figure 3). However, the character of energy dissipation let us to divide the crack propagation process into two stages: constant value of heat flux on the first stage of the test and a sharp increase in the end (figure 4). These stages couldn’t be seen at fatigue crack propagation plots (Paris’ law) and crack growth evolution plots. a b

Fig. 3. Crack rate versus stress intensity factor for uniaxial (a) and biaxial (b) loading, R is the stress ratio, η is the biaxial coefficient.

a

b

Fig. 4. Heat dissipation during uniaxial (a) and biaxial (b) fatigue tests.

In previous work by Vshivkov et al. (2017) theoretical approach for calculation of heat dissipation during fatigue crack propagation was proposed. The plastic work can be described as: