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Mass Unbalance In An Met Course

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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

Curriculum in Mechanical Engineering Technology: Part II

Tagged Division

Engineering Technology

Page Count


Page Numbers

15.855.1 - 15.855.10



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Paper Authors


Nancy Denton Purdue University

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Nancy L. Denton, PE, CVA III, is a professor and the associate department head for the Purdue University MET Department. Her educational endeavors focus on awareness and inclusion in STEM and experimental mechanics, while her research interests include applications of machinery monitoring and data acquisition. She is active in ASEE and serves as the Academic Director for the Vibration Institute.

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Marc Williams Purdue University

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Marc E. Williams does contract work in the field of vibration analysis. He has extensive experience with rotating and reciprocating equipment in the Power, Paper, Steel and Food Processing Industries. Williams holds an M. S. in Mechanical Engineering Technology from Purdue University and is certified as a Vibration Analyst Category III from the Vibration Institute.

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Joseph Kmec Purdue University

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Joseph F. Kmec is currently Associate Professor in Mechanical Engineering Technology at Purdue University, West Lafayette, IN. His teaching areas of concentration are energy-based and include Applied Thermodynamics, Internal Combustion Engines, Motorsports, and Power Plant Systems. His recent activities involving student projects include engine simulation, power plant performance analysis, and nuclear technology. He may be reached at:

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NOTE: The first page of text has been automatically extracted and included below in lieu of an abstract

Mass Unbalance in an MET Course Abstract

Mass unbalance, the condition where the centers of mass and rotation differ, is one of the most common sources of vibration in rotating machinery. Mechanical Engineering Technology (MET) students are likely to encounter vibration throughout their careers and need to understand its generation, transmission, and testing. Conveying vibration concepts effectively to students who typically have only limited exposure to differential equations presents a challenge for engineering technology faculty. Mass unbalance and related corrective procedures offer a practical venue for communicating fundamental vibration concepts, design concerns, experimental techniques, data analysis, and dynamic balancing methods to engineering technology students. The purpose of this paper is to document the versatility of mass unbalance and balancing as an instructional aid in an upper division elective course in machinery health monitoring. Examples of student assignments incorporating mass unbalance are presented. Results of ongoing assessment of related course learning objectives are provided.

Technical Background

Working from theory for a simple single degree of freedom vibrating system undergoing forced vibration, the force due to a rotating mass unbalance is the product of the eccentric mass, m, and its rotational acceleration component, eωf2, where e is the offset distance from the center of rotation to the eccentric mass and ωf is the rotor’s rotational speed in units of radians per second. The resulting applied force is modeled as F(t) = (meωf2)sin(ωft).1 Experimental data verifies the vibration energy caused by mass unbalance is essentially all included in a single sine wave at the frequency corresponding to operating speed.

Figure 1. Typical unbalance condition

Awareness of the existence of mass unbalance dates back at least several centuries.2 As machinery operating speeds have increased, understanding the force that mass unbalance causes

Denton, N., & Williams, M., & Kmec, J. (2010, June), Mass Unbalance In An Met Course Paper presented at 2010 Annual Conference & Exposition, Louisville, Kentucky. 10.18260/1-2--16131

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