Relation between intensity of singular stress at interface edge and stress intensity factor of small edge interface crack in butt joint

This paper deals with the effect of adhesion layer and material combination on the stress intensity factor for small edge interface crack in butt joint plate under uniaxial tension. The stress intensity factors of the small edge interface crack are analyzed by the crack tip stress method with varying the crack length, adhesive thickness and material combination. The stress intensity factor of the edge interface crack is controlled by the singular stress field at the interface free edge in butt joint without the crack when the crack is very small. The calculation shows that the stress intensity factors K1 and K2 of the small edge interface crack are related to the intensity of singular stress field Kσ and the singularity index λ12 at the interface edge without the crack. Then, it is found that the stress intensity factors can be expressed as K1 ＋iK2 = (F1 ＋iF2)Kσaλ12－0.5 √π(1＋2iε) and the normalized stress intensity factors F1 and F2 are constant values when the crack length a/h<10-2 irrespective of the adhesive thickness and length of butt joint plate. Therefore, it can be concluded that K1 and Kσ are an equivalent parameter each other.