On the interaction of channeling/segmentation cracks of coating: Study on the critical spacing

Channeling/segmentation cracks may arise in the coating subjected to in-plane tensile stress. The interaction between these multiple cracks, say the effect of the spacing between two adjacent cracks on the behaviors of channels themselves and the interface around the interface corners, attracts wide interest. However, if the spacing is greater than a specific magnitude, namely the Critical Spacing (CS), there should be no interaction between such channeling/segmentation cracks. In this study, the mechanism of the effect of the crack spacing on the interfacial stress around the interface corner will be interpreted firstly. Then the existence of the CS will be verified and the relationship between the CS and the so-called stress transfer length in coating will be established for plane strain condition. Finally the dependence of the stress transfer length, simultaneously of the CS, on the sensitive parameters will be investigated with finite element method and expressed with a simple empirical formula.