PSI - Issue 39

Bineet Kumar et al. / Procedia Structural Integrity 39 (2022) 222–228 Author name / Structural Integrity Procedia 00 (2019) 000–000 and 200mm having 12.5mm aggregate size. The calibration result has been shown in the Fig. 2(a) between n value and factored specimen size � D+ D D 0 � . It can be seen with the Fig. 2(a) that n is decreasing with increase in � D+ D D 0 � , and showing high rate of correlation of 0.75 with negative sign. Further, the proposed expression (8), variation between crack growth rate with the effective crack length has been validated with the previous study results (Chen, Chen and Guo (2019), Li et al . (2020), Shah and Chandra Kishen (2012)) which is shown in Fig. 2(b), and it has been found that model result is in good agreement with previous study result. Fig. 3 is showing, with increase in loading frequency, crack growth rate decreases, i.e. it will take more number of loading cycle to reach the critical crack length, so, it can be concluded that with increase in loading frequency, structure will be serviceable up to more number of loading cycle. 227 6

Fig. 2. (a) Calibration of proposed model; (b) validation of proposed model result

Fig. 3. Variation of crack growth rate with loading frequency.

5. Conclusion In this study, consideration of scale effect has been taken to develop the crack growth rate expression using nano mechanics approach, which also encounters the loading frequency effect has following outcomes. • Crack growth rate increases with increase in effective crack length. • Crack growth rate is decreasing with increase in loading frequency, i.e. structure will show larger fatigue