A study of fatigue crack closure in polycarbonate CT specimens

Elastic–plastic fatigue crack growth analysis under variable amplitude loading spectra

“…Moreover, the crack tip crack closure cannot be used in order to explain fatigue crack growth delays induced by overloads in plane strain conditions at high stress ratios. The finite element data produced by Wei and James [21] confirmed that the crack opening load depends also on the stress state in the vicinity of the crack tip.…”

Numerical simulation of plasticity induced crack closure: Identification and discussion of parameters

“…Solanki et al [28] indicated that a crack growing under cyclic loading with R = 0 had a reversed plastic zone about 1/10 the size of the forward plastic zone (while for a stationary crack this is about 1/4 the size). Therefore, if L 1 is too large, the occurrence Number of load cycles between crack increments (P2) [35] Number of crack increments necessary for stabilisation (Da = RDa i P r p,m ) [21,28,35,37] Closure definition Last contact or inversion of stresses at crack tip [22,44] Crack opening or crack closure [36,45] of reversed plasticity will not be modelled. The increase in DK, produced by the increase in crack length or Dr, and the use of higher order elements may be accomplished by an increase in L 1 .…”

“…Pommier [30] and Roychowdhury and Dodds [21] considered the second node behind the crack tip; -the occurrence of compressive stresses at the crack tip [50]. Important differences in crack closure levels are apparent when comparing the classical definition with stress inversion [22,50,51]; -parameters based on remote measurements of displacements or strains, replicating experimental measurements [3]; -a load corresponding to a zero stress intensity factor. Shterenlikht et al [52] applied optical techniques to determine the stress intensity factor and considered that crack closure occurs when K = 0; -the stress intensity factor required to open the crack, computed using the contact stresses along the closed or partially closed crack under minimum load [44].…”

Investigation of Mesh Sensitivity Influence to Determine Crack Characteristic by Finite Element Methods

“…There are so many references [9][10][11][12][13][14][15] which the problem is modeled by finite element method. Due to a great scattering in the experimental results [15][16][17][18], direct comparison of numerical and experimental results does not add conclusive criteria about the validity of the numerical results [8].…”

“…Thereupon Fleck [9] worked on the plane strain case, then Chermahini [9][10][11][12][13][14][15][16][17][18][19][20] continued this line of research with the three-dimensional models. Then McClung and Sehitoglu [21][22][23][24][25][26][27] investigated the influence of various parameters and different aspects such as the study of the plastic zone size.…”