An investigation of the stress singularity near the free edge of scarf joints

The singular stress field which develops at the interface corner of a scarf joint between two bonded elastic solids is investigated. Depending upon the scarf angle and the material elastic properties, the singular stresses at a radial distance r from an interface corner may be expressed in the form Hr(lambda-1), where lambda - 1 is the order of the stress singularity and H is the intensity of the singularity. The intensity H of the singularity at the interface corner of scarf joints subjected to a remote uniform tension is evaluated for various material combinations and a range of scarf angles using a combination of the finite element method and a path independent contour integral. Two types of scarf joints are considered: (i) a scarf joint between two long bi-material strips and (ii) a scarf joint consisting of a thin elastic layer sandwiched between two substrates. The role of the intensity H, which determines the amplitude of the stress field within the singularity zone, is examined and the implications of the results for the initiation of joint failure are discussed. (C) Elsevier, Paris.