PSI - Issue 28

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

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Fig. 7. Relation between crack growth rate and heat dissipation: measured value (a) and normalized (b).

4. Conclusion In this work, experimental and theoretical studies of energy dissipation at fatigue crack tip in Grade 2 titanium alloy were carried out under uniaxial and biaxial loadings. Theoretical analysis of the energy dissipation induced by irreversible deformation at the crack tip was carried out. A separate analysis of monotonic and cyclic plastic zones at the crack tip allowed us to propose relation for evolution of heat dissipation during fatigue test. Based on the experimental data obtained by contact heat flux censor we derived universal coefficients of this approximation for all studied loading conditions. For Grade-2 titanium alloy the approximation can be written as     2 2 1 2 , , p p p dl dl U W r W r dN dN         (4) where α = 3.6e-17 [W/Pa2]; β = 3.3e-12 [W/(Pa2*m)]. Combination of theoretical approximation and experimental data processing enable to demonstrate a linear correlation between crack growth rate and heat dissipation. Universality of this correlation gives promising possibilities in development of new techniques for estimation of fatigue behaviour of metallic structures under complex loading. Acknowledgements The results about uniaxial fatigue tests were obtained within the framework of state task; state registration number of the topic АААА-А19-119013090021-5. The reported study about biaxial fatigue tests was funded by RFBR, project number 20-31-70018. References

Bär U., Vshivkov A., Plekhov O., 2015. Combined lock-in thermography and heat flow measurements for analysing heat dissipation during fatigue crack propagation, Fracture and structural integrity 34, 521-530.