Experimental and Analytical Modal Analysis of Cantilever Beam for Vibration Based Damage Identification Using Artificial Neural Network

This paper presented procedures of experimental and analytical modal analysis of cantilever beam used for vibration-based damage identification using an artificial neural network (ANN). It is a part of structural health monitoring. The process of implementing a damage detection strategy for aerospace, civil, and mechanical engineering structures is referred to as SHM. Experimental modal analysis involves acquisition of point-to-point frequency response functions at a set of points for a dynamic model. Analytical modal analysis uses differential equations of motion of a structure using a theoretical and finite element modeling technique. In experimental modal analysis, the transient excitation method of modal testing is conducted using an impact hammer test. We considered two cantilever beams of different materials, i.e., aluminum and stainless steel. Different crack lengths were introduced on the beams by cutting the slot. Slot lengths were 2, 4, 6, 8, and 10 mm, with cracks designated as damage level 1, 2, 3, 4, and 5, respectively. The undamaged cantilever structure was treated as damage level 0. The analytical modal analysis was performed using ANSYS 15. The geometric models for analytical modal analysis were developed using CATIA V5R20. A cantilever beam of longitudinal crack at different crack lengths and materials was considered for analysis. The experimental modal analysis was validated with analytical modal analysis. It was observed that there was no change in the first mode; for higher modes, there is a decrease in natural frequencies with the increase in crack length. Frequency response functions were obtained from the experimental modal analysis. These can be used for damage identification using ANN.