Damage Localisation in Composite Laminated Plates using Higher Order Spatial Derivatives

Abstract

A new vibration based damage localisation method relying on differences of third and fourth order spatial derivatives of modal displacements of composite laminated plates is proposed in this paper. The damage is simulated by decreasing the laminate stiffness of specific finite elements. Since the displacement fields of the damaged plate are discrete, they are differentiated using higher order finite differences. The modal displacement fields of the undamaged plate are obtained using the Ritz method and, therefore, the spatial derivatives are computed analytically. Parametric studies relating the number of measured degrees of freedom to the quality of the damage localisations are carried out. The results of the present method are compared with the results obtained with an extension of the well-known rotation and curvature methods. It was found that higher order derivatives, in particular fourth order derivatives, are very promising for damage localisation in composite laminated plates.