Figure 4
From: Biaxial stress controlled three-dimensional helical cracks
Variation of the helix angle θ with the dimensionless parameters t=σ2/σ1 and η=η(c/R). (a) Variation of θ with σ1/σ2 with different values of η. (b) 3D map of θ as a function of σ2/σ1 and η. (c) Parameter regions of σ2/σ1 and η that dominate the two different cracking mechanisms. In the upper region (green), the energy released by surface cracking overwhelms that of interface delamination, whereas in the lower region (pink), interface delamination is dominant. (d) Contour map of θ with σ2/σ1 and η, showing the regions where the two cracking mechanisms prevail.
