Asee peer logo

Effective Use Of Experimentation And Finite Element Analysis In A Vibrations Course

Download Paper |

Conference

2005 Annual Conference

Location

Portland, Oregon

Publication Date

June 12, 2005

Start Date

June 12, 2005

End Date

June 15, 2005

ISSN

2153-5965

Conference Session

Improving Statics and Dynamics

Page Count

12

Page Numbers

10.511.1 - 10.511.12

Permanent URL

https://peer.asee.org/14771

Download Count

70

Request a correction

Paper Authors

author page

John Baker

Download Paper |

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

Effective Use of Experimentation and Finite Element Analysis in a Vibrations Course

John R. Baker Department of Mechanical Engineering University of Kentucky

Abstract

It is a challenge for many students to firmly grasp the relationships between calculated results from textbook equations for multi degree of freedom structural vibration and actual behavior of a structure. While students can easily perform the calculations, they often do not fully understand how the theoretical results relate to behavior of an actual system. Experimentation is often included in courses to help bridge the gap between theory and actual system behavior. This paper outlines an approach that seems to be effective which combines experimentation, including use of smart materials, with the high-level graphics and animation capabilities available in a commercial finite element (FE) code, ANSYS.

Initial experimentation involves a simple structure, then structures with increasing levels of complexity are considered. The first system involves flexible springs and standard laboratory masses. Students set initial conditions by displacing masses by hand to produce motion dominated by one of two modes. Natural frequencies are determined using a stopwatch and counting oscillations. The results agree well with calculations based on theory for the lumped mass system. The simple system is also modeled in ANSYS, the natural frequencies are calculated, and the mode shapes are animated. The second experiment involves cantilevered beams. One thin, flexible beam includes piezoelectric patches, mounted such that an applied voltage produces a moment. Natural frequencies are determined experimentally from impact tests. Natural frequencies are also calculated from partial differential equation solutions and FE analysis. The mode shapes are animated in ANSYS. The beam is then excited with a sinusoidal voltage. The displacement pattern for vibration response due to excitation at either of the first two natural frequencies can be easily detected visually, and clearly agrees with theory and animated mode shapes from ANSYS. By varying the excitation frequency, the concept of large amplitude response for excitation near resonance is clearly demonstrated. A final experiment involves test and analysis of a compressor stator vane, for which a theoretical solution is not available.

The overall approach seems to provide the students with a good foundation in theory, basic modal testing techniques, practical application of a widely used commercial finite element code, and also a brief introduction to smart materials (PZT).

“Proceedings of the 2005 American Society for Engineering Education Annual Conference & Exposition Copyright  2005, American Society for Engineering Education”

Baker, J. (2005, June), Effective Use Of Experimentation And Finite Element Analysis In A Vibrations Course Paper presented at 2005 Annual Conference, Portland, Oregon. https://peer.asee.org/14771

ASEE holds the copyright on this document. It may be read by the public free of charge. Authors may archive their work on personal websites or in institutional repositories with the following citation: © 2005 American Society for Engineering Education. Other scholars may excerpt or quote from these materials with the same citation. When excerpting or quoting from Conference Proceedings, authors should, in addition to noting the ASEE copyright, list all the original authors and their institutions and name the host city of the conference. - Last updated April 1, 2015