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Unformatted text preview: Homework 1_Solution Acoustics I Fall 2007 A SDOF system shown in the figure below is operating on a foundation of impedance F Z % defined by 6 6 27,000 1.875 10 270 10 3000 , 3000 , 3000 F Z j j or =--- % . Plot the displacement amplitude 1 X % of mass M 1 when F = 1 as a function of frequency for the range 0 500 / rad s =- for these three cases. (Solution) The impedance at the excitation point is given as: 1 1 1 j t m m m j t m m F F s js R R f Fe j Z j M j M s js x j X e R R j Z Z +- = = = + = + +- + + % & % % % % % (1) For F = 1, 1 1 m X j Z = % % (2) 1 27,000 / s N m = 1 180 / m R N s m = 1 x % ( ) j t f t Fe = % 1 300 M Kg = F Z % Therefore, 1 X % is obtained: (1) Calculate F Z % as a function of . (2) Calculate m Z % from Eq. (1) as a function of for the calculated F Z % ....
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This note was uploaded on 10/19/2009 for the course MECH 666 taught by Professor Kim during the Fall '07 term at University of Cincinnati.
- Fall '07