Failure Mechanisms

· Estimates by Paris of the crack growth rate for a random loading situation employ the rms value of the stress intensity factor: (da/dN) = C (ΔK_rms)^m, where for a series of n cycles with a stress intensity factor range, ΔK_i , for

the i^th cycle:
· The diagrams indicate that normalizing the stress intensity range by Young's modulus removes the material sensitivity of the crack growth rate data.