PSI - Issue 3

G.M. Domínguez Almaraz et al. / Procedia Structural Integrity 3 (2017) 562–570 Author name / Structural Integrity Procedia 00 (2017) 000–000

568

7

The crack growth experimental results are depicted on the graph of Figure 8: fatigue crack growth rate (m/cycle), against the stress intensity factor range threshold (  K TH ). The stress intensity factor rate (MPa·m 0.5 /s) under these ultrasonic fatigue tests was close to 40,000.

(a)

(b)

(c)

(d)

(e)

(f)

Fig. 7. Fracture surfaces of PMMA under ultrasonic fatigue testing: (a), (b) and (c) applied load of  6 MPa, and (d), (e) and (f) applied load of  9 MPa.

Fig. 8. Crack growth rates for PMMA under ultrasonic loading and immersed in water.