CUED Publications database

Motion magnification for mode shape determination

Bao, Y and Seshadri, P and Mahadevan, S (2017) Motion magnification for mode shape determination. In: UNSPECIFIED.

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We present the results of an experimental study aimed at using high speed videos to determine the harmonics of vibrations of structures, and their associated mode shapes under noise. One of the technologies that underpin the results in this paper is phase- based motion magnification: visual magnification of micro-motions using high speed videos. In this paper a cantilevered beam is instrumented with nine accelerometers from root to tip. When forced into free vibration (via an impulse hammer), a high speed video of the vibrating beam is taken and subsequently post-processed. Using a phase-based algorithm for magnifying the small movements of the beam, along with an optical flow algorithm for calculating velocities, mode shapes of the beam are recovered. Some challenges which are common for experiments, such as ashing effect due to alternative current and unevenly distributed luminance along the object were overcome by image enhancement techniques. The recovered mode shapes were found to match analytical predictions from Timoshenko beam theory and the accelerometer data.

Item Type: Conference or Workshop Item (UNSPECIFIED)
Divisions: Div A > Turbomachinery
Div A > Energy
Depositing User: Unnamed user with email
Date Deposited: 17 Jul 2017 19:26
Last Modified: 15 Apr 2021 02:26