Localization and Identification of Damageof Cantilever Beam Using Modal Indicsand Fuzzy-ksom Model

ABSTRACT In the presentwork finite element method and fuzzy-KSOM hybrid technique are used for localization of damagepresent in form of cracks in the cantilever beam. The presence of cracks in the beam like structures is a serious threat to the performance as well as integrity of structures and itschange the modal indics e.g. natural frequencies and mode shapes of the structures.The glass fiber reinforced epoxy compositeis engaged in the present investigation due to its advantageous features, such as higher damage tolerance capability, improved fatigue resistance, high stiffness and strength-to-weight ratios compared with the metallic structures. The finite element analysis has been performed on the ANSYS software to establish the relation between the change in modal characteristics for the cracked and not-cracked composite beam. These changes in modal characteristics (first three relative natural frequencies, first three average relative mode shape difference)are used as input parameters to the fuzzy segment of the hybrid model and relative crack depths and crack locations are the output parameters of fuzzy model. The first three relative natural frequencies, first three average relative mode shape difference and the outputs from the fuzzy model are used as inputs to the KSOMsegment of the hybrid model and final crack depths and locations are the outputs of hybrid model. The modal characteristics are used to formulate a series of fuzzy rules and training patterns for the fuzzy and KSOM. The results obtained from proposed model isauthenticated by experimental analysis results from the developed experimental setup.