• Arizona State University

• MEE 322

Free and Forced Vibrations due to Rotating Unbalance

Name:
Lab Number:
Objective:
 
1. Measure the equivalent stiffness of a beam to be used as a spring during the vibration
experiment and compare it with the theoretical result obtained from using the equivalent stiffness
technique for beams, as well as the dynamic response of the system.
2. Measure the free vibrations of a mass-beam system and compare it with theoretical predictions
for a single degree of freedom damped system and use the measured amplitude decrease to
determine the damping ratio of the system, as well as the damped natural frequency and compare
the latter with theoretical predictions.
3. Obtain the frequency response of the system by measuring amplitude versus time under
various rotating speeds of the unbalanced motor and use the results to determine the resonant
frequency, normalized amplitudes and phase shift as functions of normalized frequency and
compare them with theoretical predictions.
4. Prepare a technical report where the experiment and the findings are described, comparisons
between the experimental findings and theoretical results are made, discussion explaining the
reasons for the different behaviors is offered and conclusions regarding these behaviors are
reached. The technical report must be properly formatted.
Abstract:
In this experiment, it consisted a mass-beam structure with the beam with an electric motor
attached to the beam. The mass was mounted in the center of the beam. The motor was attached
to controls that gathered data while it rotated with different speeds and record data of the
deflection of the beam. We found that our experimental values agreed with our theoretical values,
even though there were some errors. We were able to relate the response of a mass beam system
to various properties and parameters of the mechanical system. With that, we are able to utilize
the method to relate the response of a system to certain properties and relationships that define
the sy