Numerical modeling of fatigue crack propagation based on the Theory of Critical Distances: Effects of overloads and underloads

A Literature Review of Incorporating Crack Tip Plasticity into Fatigue Crack Growth Models

“…In works [87,88], a numerical model based on the theory of critical distances (TCD) is proposed. This theory is not new [7,89], and essentially consists of ensuring that crack propagation will occur when a certain physical quantity, at a given location in front of the crack front, reaches a specific value.…”

“…An important step is to study how mesh size and microstructure size affect these outcomes; the latter was investigated because the adjusted critical distance is of the order of the microstructure size, and several authors have previously focused on this detail [90,91]. Subsequently, in another paper [88], the same authors tested the goodness of the method against varying conditions of overload, underload, acceleration, and deceleration of the loading cycles, as well as the moment (crack length) at which this is done. The model responded satisfactorily with respect to the experimental results obtained.…”

“…They can be divided into groups: terms related to plastic strain energy, elastic strain energy, strain energy gradient, total strain energy, and specific energy. The terms related to plastic strain energy are plastic CTOD [67], plastic energy in the point used in PM [87,88], Kujawsky and Ellyin plastic energy [90,91], ∆W p [79,83,84], U pl [81], and Q [83]. All of these consider a threshold of the plastic energy that triggers the crack growth when surpassed.…”

Effect of stop-hole-induced material removal on the fatigue properties of cracked DT4C steel

“…1 The investigation of crack-growth retardation is a significant subject for increasing the remaining lives of cracked structural components. 2 There are a number of methodologies of delaying or arresting crack growth to extend the fatigue lives of cracked components, such as welding repair, 3,4 tensile overload(s), [5][6][7] shot peening, [8][9][10][11][12] indentation, 13,14 and deposition. 15 Beyond that, drilling a round hole in the vicinity of fatigue crack-tip, often named the stophole method, is one of the most effective and the easiest crack-growth arresting or retardation techniques for cracked components, 16,17 which is more effective than infiltration and safer than applying an overload.…”