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Five Forced-Vibration Laboratory Experiments using Two Lumped Mass Apparatuses with Research Caliber Accelerometers and Analyzer

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2011 ASEE Annual Conference & Exposition


Vancouver, BC

Publication Date

June 26, 2011

Start Date

June 26, 2011

End Date

June 29, 2011



Conference Session

Mechanical Engineering Laboratories I

Tagged Division

Mechanical Engineering

Page Count


Page Numbers

22.723.1 - 22.723.17



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Paper Authors


Richard J. Ruhala Southern Polytechnic State University

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Richard Ruhala earned his B.S.M.E. from Michigan State in 1991 and his Ph.D. in Acoustics from The Pennsylvania State University in 1999. He has three years industrial experience at General Motors and three years at Lucent Technologies. He was an Assistant Professor in the Engineering Department at the University of Southern Indiana before joining the faculty at Southern Polytechnic State University in 2010 as an Associate Professor, where he also serves as director for their new mechanical engineering program. He has taught a wide spectrum of engineering and mechanical engineering courses. He is a member of ASEE, the Acoustical Society of America, and the Institute for Noise Control Engineering, and conducts research in acoustics and vibrations.

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Four Forced-Vibration Laboratory Experiments using two Lumped Mass Apparatuses with Research Caliber Accelerometers and AnalyzerAbstractIn 2004 a 3-credit engineering elective course in vibrations was created. It consists of two hoursof lecture and three hours of lab per week. One commercially available translational system andone rotational lumped mass system were purchased. Each turn-key system can be adjusted tostudy one, two, or three degrees of freedom systems in which the masses/inertial values caneasily be changed. In addition, the translational system has three different types of springs andone variable air cylinder dashpot to choose from. Both systems come with an amplifier andmotor which can optionally drive one of the masses in motion that is proportional to the signalon the input. However, instead of using the optical sensors, accelerometers were procured thatare more representative of what engineers use in industry. Likewise, instead of purchasing thecomputer board and software that accompanies the lumped mass apparatuses (which in this casewas primarily developed for controls laboratory experiments), a world-class analyzer (thatincludes computer software for control) was purchased so that the sensors and analyzer can beused by students and faculty for research projects. This created a hybrid approach that combinesthe best combination of turnkey and custom systems. The analyzer can also be used foracoustical measurements. A disadvantage is that the software that controls the analyzer is notuser friendly, and requires substantial setup time by the instructor. The laboratory experimentsthat were developed include the study of free vibration, forced vibration, 1 DOF, 2DOF, and 3DOF systems, dynamic absorber, modes of vibration, and the effects of damping. In a 2010ASEE Conference paper, four free-vibration experiments were described in detail. In this paperfour forced-vibration experiments will be described in detail, as well as their impact on thestudent learning outcomes for the course. Other experiments were developed without theturnkey apparatuses to evaluate strings and consumer products. All experiments were developedand refined over several years. Student surveys have indicated that the laboratory experimentswere effective in understanding the theory and provide an increased level of intellectualexcitement for the course.

Ruhala, R. J. (2011, June), Five Forced-Vibration Laboratory Experiments using Two Lumped Mass Apparatuses with Research Caliber Accelerometers and Analyzer Paper presented at 2011 ASEE Annual Conference & Exposition, Vancouver, BC. 10.18260/1-2--18004

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