The double cantilever beam (DCB) specimen has considerable potential for application to fracture toughness testing because it facilitates the determination of a number of plane strain toughness data from a single specimen of moderate size. The relationship between the elastic strain energy release rate, load, and extension for a given crack length is obtained from compliance tests and the dependence of this relationship on the specimen geometry is presented. The effect of changing specimen geometry on the fracture toughness is also presented. Comparison with plane strain toughness data obtained by other techniques on identical materials is made to evaluate the effectiveness of the side grooves in the specimen for providing plane strain conditions at fracture. Finally, consideration of the meaning of the stress intensity at crack arrest in the DCB specimen indicates that this parameter is dependent on specimen geometry as well as the material properties.
A DOUBLE CANTILEVER BEAM SPECIMEN FOR DETERMINING THE PLANE STRAIN FRACTURE TOUGHNESS OF METALS