ICSV21, Beijing, China, 13-17 July 2014 1 The 21 st International Congress on Sound and Vibration 13-17 July, 2014, Beijing/China IDENTIFICATION OF SKIN/CORE DEBONDING IN HON- EYCOMB ALUMINIUM PANELS THROUGH AN INVERSE METHOD BASED ON PARALLEL GENETIC ALGO- RITHMS Viviana Meruane, Valentina del Fierro Department of Mechanical Engineering, Universidad de Chile. Beauchef 850, Santiago, Chile. e-mail: vmeruane@ing.uchile.cl Honeycomb sandwich structures are used in a wide variety of applications. By sandwiching the core between two faces, a structure of superior bending stiffness and low weight is ob- tained. Nevertheless, due to manufacturing defects or impact loads, these structures can be subject to imperfect bonding or debonding between the skin and the honeycomb core. The presence of debonding reduces the bending stiffness of the composite panel, which causes de- tectable changes in its vibration characteristics. This article presents a new methodology to identify debonded regions in aluminium honeycomb panels that uses an inverse algorithm based on parallel genetic algorithms. The honeycomb panels are modelled in finite elements using a simplified three-panel shell model. The adhesive layer between the skin and core is modelled using linear springs, the rigidities of which are reduced in debonded sectors. The algorithm is validated using experimental data of an aluminium honeycomb panel under dif- ferent damage scenarios. 1. Introduction The applications of sandwich structures continue to increase rapidly, ranging from satellites, aircrafts, ships, automobiles, rail cars, wind energy systems and bridge construction, among others 1 . Sandwich panels typically consist of two thin face sheets or skins and a lightweight thicker core, by sandwiching the core between two faces, a structure of superior bending stiffness is obtained. Nev- ertheless, due to manufacturing defects or impact loads, these structures can be subject to imperfect bonding or debonding between the skin and the honeycomb core. Debonding in a sandwich struc- ture may degrade severely its mechanical properties, which can produce a catastrophic failure of the structure. Therefore, it is important to detect the presence of debonding at an early stage. A disadvantage of sandwich structures is that their structural failures, especially in the core, cannot always be detected by traditional non-destructive detection methods. A global technique called vibration-based damage detection has been rapidly expanding over the last few years 2 . The basic idea is that vibration characteristics (natural frequencies, mode shapes, damping, frequency response function, etc.) are functions of the physical properties of the structure. Thus, changes to the material and/or geometric properties due to damage will cause detectable changes in the vibra- tions characteristics. A debonded region in a sandwich structure is equivalent to a delamination of composite laminates 6 . Many studies have demonstrated that vibration characteristics are sensitive to