Simulation of fatigue crack growth in components with random defects

Base material fatigue data for low alloy forged steels used in the subsea industry. Part 1: In air S–N data

“…The deviation from this relationship is reported to be due to the presence of defects which are larger than a critical size and for material with a Vicker hardness larger than 400 (or a tensile strength > 1300 MPa) [38]. See [39][40][41]38,42,43] for models that describes the influence of crack-like defects on the fatigue strength.…”

Finding truth in fictions: identifying non-fictions in imaginary cracks

“…will focus on the work of Fjeldstad et al (2008). Their method begins with the observation that manufacturing processes inevitably introduce flaws of various types and magnitudes throughout a material.…”

“…The authors note that, though they are randomly distributed, it is not without constraints; rather, the random distribution is mapped to a particular probability distribution across the structure based on what is known about the manufacturing process and the existing wear on the structure (Fjeldstad et al 2008(Fjeldstad et al , 1187. Looked at in this way, then, the distribution of imaginary cracks (but not necessarily the cracks themselves) is a straightforward idealization -should the probability mapping be replaced with one that more realistically represents the actual distribution of flaws that results from chaotic production processes, then the resulting representational model would always be more accurate, since it would have to rely less on the emergent distribution's statistical representativeness.…”

“…Their method begins with the observation that manufacturing processes inevitably introduce flaws of various types and magnitudes throughout a material. These flaws stem from chaotic elements in the manufacturing process, leading to "variability of chemical composition, microstructure and mechanical properties" (Fjeldstad et al 2008(Fjeldstad et al , 1186. Practitioners have long known that these flaws, regardless of their type, can be treated as though they are microcracks, so long as they are small relative to the structure and one is interested only in modelling the structure as a whole (Waddoups et al 1971).…”

Influence of random shrinkage porosity on equivalent elastic modulus of casting: A statistical and numerical approach

“…Because of this inhomogeneous and random characteristic, the mechanical performances of castings with shrinkage porosity were uncertain [19,20] . Moreover, the crack growth behaviors were correlated with the probability distributions, such as the number (defect density), size, and location of defects [21,22] . It was complicated to obtain this kind of random-defected material's mechanical function by traditional determinable methods [10,23] .…”