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Four Free Vibration Laboratory Experiments Using Two Lumped Mass Apparatuses With Research Caliber Accelerometers And Analyzer

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2010 Annual Conference & Exposition


Louisville, Kentucky

Publication Date

June 20, 2010

Start Date

June 20, 2010

End Date

June 23, 2010



Conference Session

Teaching Dynamics

Tagged Division


Page Count


Page Numbers

15.599.1 - 15.599.16



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Paper Authors


Richard Ruhala Southern Polytechnic State University

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Richard Ruhala earned his BSME from Michigan State in 1991 and his PhD in Acoustics from The Pennsylvania State University in 1999. He has 3 years industrial experience at General Motors and 3 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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NOTE: The first page of text has been automatically extracted and included below in lieu of an abstract

Four Free-Vibration Laboratory Experiments using two Lumped Mass Apparatuses with Research Caliber Accelerometers and Analyzer


In 2004 a 3-credit engineering elective course in vibrations was created at the University of Southern Indiana. It consists of two hours of lecture and three hours of lab per week. One commercially available translational system and one rotational lumped mass system were purchased. Each turn-key system can be adjusted to study one, two, or three degrees of freedom systems in which the masses/inertial values can easily be changed. In addition, the translational system has three different types of springs and one variable air cylinder dashpot. Both systems come with an amplifier and motor which can optionally drive one of the masses in motion that is proportional to the voltage signal on the input. However, instead of using the optical sensors, accelerometers were procured that are more representative of what engineers use in industry and research, as well as provide instrumentation knowledge and skills. Likewise, instead of purchasing the computer board and software that accompanies the lumped mass apparatuses (which in this case was primarily developed for controls laboratory experiments), a world-class analyzer (that includes computer software for control) was purchased so that the sensors and analyzer can be used by students and faculty for research projects. This analyzer can also be used for acoustic measurements. A disadvantage is that the software that controls the analyzer is not user friendly, and requires substantial setup time by the instructor. The laboratory experiments that were developed include the study of free vibration, forced vibration, 1 DOF, 2DOF, and 3 DOF systems, dynamic absorber, modes of vibration, and the effects of damping. In this paper, only the free vibration experiments, four in all, will be described in detail, as well as their impact on the student learning outcomes for the course. These experiments were developed and refined over several years. Each laboratory workstation can accommodate two students at a time. Student surveys have indicated that the laboratory experiments were effective in understanding the theory and provide an increased level of intellectual excitement for the course. A subsequent paper is planned to describe the forced vibration experiments.


There are two basic approaches to developing a vibrations laboratory for engineering students to study lumped parameter systems. One is to purchase a commercially available turnkey system complete with hardware and software. The other is to design and build a custom apparatuses to go with a research caliber accelerometers and analyzer, as well as potential software development. The laboratory experiments described in this paper use another approach which is a hybrid of the two.

Ruhala, R. (2010, June), Four Free Vibration Laboratory Experiments Using Two Lumped Mass Apparatuses With Research Caliber Accelerometers And Analyzer Paper presented at 2010 Annual Conference & Exposition, Louisville, Kentucky. 10.18260/1-2--16303

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