About the Influence of Butt Weld Joints Geometry on the Damage Detection Process

Abstract

The number and diversity of global nondestructive testing methods applicable to welded structures have rapidly increased in last decades. Vibration-based damage detection methods make possible the evaluation of structures at once; the damage location can be found without having direct access to the structure’s damaged region. Butt welded components often bring complexity in the structures, since the weld introduces cross-section shape changes and alteration of the material’s physical and mechanical characteristics. Moreover, the structure continuity can be interrupted by cracks or cavities. All changes occurring due to the weld induce mutations in the structures dynamical behavior. This paper presents a method to identify structural changes by using information from the modal analysis, actually analyzing the natural frequency shifts. Mathematical relations describing the individual or coupled effect of mass change and geometrical discontinuities are derived and used in the identification process; in fact, finding the mass changes or cracks becomes an inverse problem. The mathematical models are successfully tested on virtual and real structures.