Global Structure Damage Estimation based on the Eigen-Frequencies

Abstract

Progressive damage processes have been discovered on various types of structures, for which a uniform theory has been unavailable. Any numerical investigation of progressive damage phenomena should be based on the load- or time-evolution of the global stiffness matrix. Hence, natural frequencies using this stiffness matrix offer a decision basis regarding the damage-induced change of structural features. A proper way to quantify structural damage is to observe the eigen frequency reduction of the overall structural stiffness. Following this relationship, we have proposed to define structural damage measures in terms of global stiffness parameters ωi.and offered a set of damage indicator Dω,i. However, applying this concept a question arises how many indicators Dω,i should be considered. In this paper we apply the improved damage indicator using the Effective Mass Ratio (EMR) or Modal Contribution Factor(MPF). By means of the new damage indicator considering the participation ratio of each eigen mode, we can get a unique value as a damage index. Three numerical examples demonstrated the applicability of this new damage indicator.