Vol.15, No.1, 2015, pp.11–14
UDC 539.42

The paper considers the problem of a crack approaching an interface between two materials at a right angle and the influence of residual stresses on its behaviour. The crack attacking the interface can behave in three ways: (a) it can disappear, i.e. it can stop at the contact with the interface; (b) it can penetrate the interface and continue to propagate into the material across it; and (c) it can deflect into the interface and continue to propagate along it. This so-called ‘competition’ between the latter two cases depends on whether the ratio of energy release rates for the crack deflecting into the interface and the crack penetrating the interface is larger or smaller than the ratio of the fracture toughness of the interface and the fracture toughness of the material across it. Residual stresses, as the consequence of the difference in thermal expansion coefficients of the two materials constituting the interface, affect the above two energy release rates. Results confirm the significant influence of difference in thermal expansion coefficients.

Keywords: interface, approaching crack, crack deflection, crack penetration, residual stresses