Smart crack detection of a cracked cantilever beam using fuzzy logic technology with hybrid membership functions

摘要

Damage detection methods have been considerably increased over the past few decades. A crack in a structural member introduces local flexibility that would affect vibration response of the structure. This property may be used to detect existence of a crack together with its location and depth in the structural member. The presence of damage leads to changes in some of the lower natural frequencies and mode shapes. Damage detection is one of the important aspects in structural engineering both for safety reasons and because of economic benefits that can result. This technique has been used in the present investigation for crack detection. Here the crack is transverse surface crack. The crack is analyzed using fuzzy logic system and finite element analysis. The fuzzy controller uses the hybrid membership functions (combination of triangular, trapezoidal and Gaussian) as input and trapezoidal membership functions as output. The input parameters to the fuzzy controller are the first three natural frequencies. The output parameters of the fuzzy controller are the relative crack depth and relative crack location. Finite element analysis has been done for modeling the cracked cantilever beam. By using Several fuzzy rules the results obtained for crack depth and crack location in the Matlab Simulink environment and have been compared with the results obtained from finite element analysis. It is observed that the fuzzy controller can predict the depths and locations accurately close to the finite element analysis. Finally, a deviation of the results obtained by comparing the finite element analysis results and fuzzy controller result.