June 12, 2005
June 12, 2005
June 15, 2005
10.1404.1 - 10.1404.14
Using Commercially Available Finite Element Software for Fatigue Analysis Cyrus K. Hagigat Engineering Technology Department College of Engineering The University of Toledo Toledo, Ohio 43606
I: Introduction Fatigue analysis is a branch of the science of fracture mechanics. It is widely known that a metal subjected to a repetitive fluctuating load will eventually fail at a load much lower than that required to cause fracture on a single application of the load.
Fatigue failures can be grouped into two broad categories of “Low Cycle Fatigue” and “High Cycle Fatigue”.
The primary cause of failure in “Low Cycle Fatigue” is large strain fluctuations. For example, extreme temperature fluctuations can cause large strain fluctuations. Another possible cause of large strain fluctuations is the large variation in centripetal forces in a high speed rotating machine during acceleration and deceleration.
The primary cause of failure in ‘High Cycle Fatigue” is fluctuating stress levels. For example, fluctuating stresses can be caused by vibration caused by a minor imbalance in a high speed rotating part.
The primary analytical technique for analyzing “Low Cycle Fatigue” is the strain-life technique, and the primary analytical technique for analyzing “High Cycle Fatigue” is the stress-life technique. The finite element technique enables one to determine the stress and strain levels for complicated geometries and loading conditions.
This article contains the background information and introduces concepts that illustrate the use of commercial finite element software as an aid in teaching fatigue analysis. The use of the finite element technique will enable an instructor to move beyond presenting simple geometries and loading conditions, and will thereby allow the teaching of fatigue analysis techniques involving real world geometries, boundary and loading conditions.
II: Cyclic Loading Fatigue failure is a byproduct of cyclic loading. Figures 1, 2 and 3 illustrate typical fatigue loading (stress) cycles.
Proceedings of the 2005 American Society for Engineering Education Annual Conference & Exposition Copyright © 2005, American Society for Engineering Education
Hagigat, C. (2005, June), Using Commercially Available Finite Element Software For Fatigue Analysis Paper presented at 2005 Annual Conference, Portland, Oregon. 10.18260/1-2--15230
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