Nondestructive characterization of the mechanical strength of diffusion bonds. I. Experimental results

The application of ultrasonic reflectivity for the characterization of a variety of copper diffusion bonds is described. The quality of each diffusion bond has been described by its ultimate tensile strength. Furthermore, fractography of the failed bonds provided information on the relative fraction of bonded areas as well as the geometry of the bonds. This paper provides the experimental results obtained as well as empirical correlations between the quantities determined.     

Application of the cohesive model for predicting the residual strength of a large scale fuselage structure with a two-bay crack

The residual strength of a curved and stiffened panel containing a two-bay crack was assessed using the cohesive model. This panel represents a section of a wide-body aeroplane fuselage. The tests were conducted at IMA GmbH Dresden in cooperation with Airbus Industries Germany. The structural panel was modelled using 3D finite elements and a layer of cohesive elements ahead of each crack tip allowing for 70 mm crack extension. Identification of the cohesive parameters was done on small laboratory test pieces. Special effort was made for the transfer of these parameters to the structure. Reasonably conservative predictions of the residual strength of the panel were achieved. The boundary conditions of the loading devices of the test rig are shown to have substantial influence on the predictions.