A two-step method for additional mass identification in beam structures by measurements of natural frequencies and guided waves

Abstract This paper presents a two-step method for the identification of additional masses in beam structures. In the first step, relative natural frequency change (RNFC) curves are developed as an indicator for identifying the possible locations of additional masses at the global level. The RNFC curves based method allows detection of possible mass locations using natural frequencies alone and as such is a significant improvement over the state of the art. To further identify the precise locations of the masses, guided wavefield imaging is used for local mass detection in the second step. The two-step method is successfully applied for the precise localization of additional masses on a simply-supported beam. The paper firstly shows that additional mass-induced RNFC curves are different from those caused by cracks in beams. As a result, a theoretical formulation and validation of additional mass identification is needed and is the main novelty of the paper.