Experimental analysis of non-uniform cantilever beam in fluid with variable depth

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In this work, we present the comprehensive study of uniform and non-uniform cantilever beams made of flexible coke can material with density 2700 kg/m3 and Young’s modulus 80.81GPa vibrating in water. The length, width and thickness of the uniform beam are taken as 5 cm, 2 cm and 0.102 mm. For non-uniform beams, the width of the fixed end of the beam is taken as 2 cm and free end width are taken as 3 cm for diverging section and 1 cm for converging section. The beams are excited using shaker and their vibration characteristics have been observed using the Laser Doppler Vibrometer (LDV). The fluid loading and dissipation effect due to water on first bending mode frequency and corresponding quality factor/damping ratio are analysed for the uniform and non-uniform vibrating cantilever beam as the wet portion of the beam increases from zero length to its full length. Finally, the results are compared with the frequencies and quality factor the beams vibrating in ambient air. It is found that the frequency of diverging beam is approximately 11.64 % less and for converging beam it is approximately 27.4 % higher than that of uniform cantilever beam. The quality factor which is inversely proportional to damping ratio is 78 % less in diverging beam and 27 % more in converging beam as compared to that of uniform beam. Finally, as the length of beam in water increases, both frequencies and quality factors reduce due to fluid loading and damping effect. It is also noticed that as the beams are completed submerged in water, both the frequencies and quality factor for converging beams are found to be more as compared to uniform and diverging beams.