Effect Of Wave Modulation Measured At Various Locations For Damage Detection Using Vibro-Acoustic Method

Ng, Chin Sern (2017) Effect Of Wave Modulation Measured At Various Locations For Damage Detection Using Vibro-Acoustic Method. Project Report. UTeM, Melaka, Malaysia. (Submitted)

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Abstract

Structural Health Monitoring has greatly developed in recent years where more advanced method was studied and applied practically in our daily lives. Among the most commonly applied in the method is the nonlinear acoustic effect excite simultaneously with low frequency. This application has been researched to determine the reliability to detect fatigue crack in specimen. In general, every material in this world is restricted to certain period of life span. There are 3 stages of fatigue failure development from the initiation of micro crack up to the fracture of the material. Crack formation is then classified into 3 modes where the mode is depends on the manner force applied on the plate. The fatigue crack propagation does not increase proportional with the number of load cycles. An aluminum plate is prepared into the required specification in order to proceed with the vibro-acoustic test. The natural frequency is determined through modal analysis and then the mode shape was confirmed using the VL scanning software. Then the first 3 mode shape frequency was excited for the vibro-acoustic analysis where the location of measurement was distributed into 25 points above the crack line. Based the modulation intensity (R-value) at each points, an analysis was done on the graph of R-value against measurement point distance from crack. Lastly, a contour plot was produced to ease the understanding on modulation intensity distribution on the measurement points for all 3 modes.

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