Three-dimensional thermal crack growth in self-stressed bimaterial joints: Analysis and experiment

Abstract

A systematic examination of the initiation and growth of thermal cracks in three-dimensional self-stressed bimaterial joints has been performed by using special models consisting of two segments of different materials, for example of glass and aluminum, and by using a well-defined cooling procedure. Besides, the initiation and development of these thermal cracks originating at one corner of such a bimaterial joint have been measured by means of a special image-processing technique. The corresponding mixed boundary value problem has been formulated, and the fracture mechanical assessment of the three-dimensional thermal crack growth has been evaluated by applying the finite element method. Fracture mechanical parameters have been obtained by two different numerical approaches both based on the FE-method. The first approach is based on Irwin's modified crack closure integral by using the so-called 3DMVCCI-technique. As a second method, the well-known J-integral has been implemented in a FE-postprocessor on the basis of the equivalent domain integral (EDI) technique. An appropriate crack growth criterion has been established in accordance with the experimental results obtained.