| description abstract | An experimental investigation has been carried out on large plates made of pressure vessel steel A516 Gr.70, to determine the fatigue crack growth rate. The specimen size was 914.4 × 304.8 × 12.7 mm (36 × 12 × 0.5 in.) with an initial central through crack of about 92 mm (3.6 in.). The stress ratio, R , applied to the specimens varied from zero to 0.4. This ratio was maintained constant during a test, but the stress amplitude, Δσ, at times was increased in order to obtain data under a large range of stress intensity factor, ΔK . The crack growth rate, da /dN , is expressed in terms of stress intensities, ΔK and K max , through a power-law-type equation. The variation of material constants with the applied stress ratio is discussed. From the data analysis, a general equation for the crack propagation rate is suggested in the form of da /dN = C (K max )n where C and n are functions of ΔK , K max and material parameters. The results are also compared with the recommended ASME Code formula and are found to be in fairly good agreement. | |
