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Unformatted text preview: ME163 Mechanical Vibrations (Winter 2009) HW-2 Due 1.22.09 in class-25% if late within 24 hours-50% if later than that 1. In order to experimentally determine the stiffness and damping coefficient of the system below, a bump test is performed. A bump test is a test which excites the dynamics in order to study its vibration. For this case the experimenter gave an initial condition in velocity as the bump and position and acceleration data was recorded of the movement. Considering that the mass is m = 20 [kg] address the questions below: (a) Construct a free body diagram and derive the equation of motion for the system. (b) Using the acceleration in plot 1, determine the natural frequency n . (c) Calculate the effective stiffness k eff . (d) Using the position trace in plot 2 determine the damped natural frequency d . (e) Calculate the damping coefficient c . k k k m c 5 10 15 20-2.5-2-1.5-1-0.5 0.5 1 1.5 2 Time [s] Acceleration [m/s 2 ] Figure 1: Acceleration response without damping ME163 Mechanical Vibrations 1 HW2 5...
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- Winter '08