Fatigue Behavior in the Presence of Periodic Overloads Including the Effects of Mean Stress and Inclusions
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University of Toledo / OhioLINK
2011
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| Online Access: | http://rave.ohiolink.edu/etdc/view?acc_num=toledo1319554971 |
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ndltd-OhioLink-oai-etd.ohiolink.edu-toledo13195549712021-08-03T06:08:03Z Fatigue Behavior in the Presence of Periodic Overloads Including the Effects of Mean Stress and Inclusions Lindsey, Justin Mechanical Engineering Periodic Overloads Life Prediction Inclusion Sulfur Effect Variable amplitude loading of components or structures can result in failures which occur much sooner than would be predicted by commonly used life prediction models, utilizing constant amplitude loading. The goal of this study was to investigate the effect of periodic overloads on fatigue behavior of smooth specimens made from five grades of steel and one grade of aluminum. This history included a periodic fully-reversed overload cycle followed by smaller cycles in the presence of a mean stress. Life predictions were performed for each test by implementing the Linear Damage Rule along with the strain-life equation or Smith-Watson-Topper (SWT) mean stress parameter. Life predictions were then compared to experimental results. Life predictions with the SWT parameter showed an increase in accuracy versus the strain-life method but there still remained predictions that were unaffected by the use of this parameter. Presence of periodic overloads in a load history resulted in increased damage for small cycles not only at strain levels above the fatigue limit, but also in damage for cycles below the fatigue limit. Additional tests were performed in order to identify the amount of damage resulting from individual aspects of the load history. These aspects included small cycles in the presence of mean stress without overloads, fully-reversed small cycles with overloads, as well as variations in the number of small cycles per load block. Comparison of these different aspects showed that in some cases the application of mean stress in the periodic overload history resulted in little to no additional small cycle damage. Anisotropy resulting from sulfide inclusions was examined by applying the periodic overload history to three sets of steel 4140 containing three different levels of sulfur content (0.004%, 0.012%, and 0.077%). The specimens were machined so that the axis of the specimen was transverse to the rolling direction of the material. Results of the testing showed that, although the sulfur content has a drastic effect on fully-reversed constant amplitude fatigue lives, there is little noticeable different between the materials with different levels of sulfur in the presence of periodic overloads. 2011 English text University of Toledo / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=toledo1319554971 http://rave.ohiolink.edu/etdc/view?acc_num=toledo1319554971 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |
| collection |
NDLTD |
| language |
English |
| sources |
NDLTD |
| topic |
Mechanical Engineering Periodic Overloads Life Prediction Inclusion Sulfur Effect |
| spellingShingle |
Mechanical Engineering Periodic Overloads Life Prediction Inclusion Sulfur Effect Lindsey, Justin Fatigue Behavior in the Presence of Periodic Overloads Including the Effects of Mean Stress and Inclusions |
| author |
Lindsey, Justin |
| author_facet |
Lindsey, Justin |
| author_sort |
Lindsey, Justin |
| title |
Fatigue Behavior in the Presence of Periodic Overloads Including the Effects of Mean Stress and Inclusions |
| title_short |
Fatigue Behavior in the Presence of Periodic Overloads Including the Effects of Mean Stress and Inclusions |
| title_full |
Fatigue Behavior in the Presence of Periodic Overloads Including the Effects of Mean Stress and Inclusions |
| title_fullStr |
Fatigue Behavior in the Presence of Periodic Overloads Including the Effects of Mean Stress and Inclusions |
| title_full_unstemmed |
Fatigue Behavior in the Presence of Periodic Overloads Including the Effects of Mean Stress and Inclusions |
| title_sort |
fatigue behavior in the presence of periodic overloads including the effects of mean stress and inclusions |
| publisher |
University of Toledo / OhioLINK |
| publishDate |
2011 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=toledo1319554971 |
| work_keys_str_mv |
AT lindseyjustin fatiguebehaviorinthepresenceofperiodicoverloadsincludingtheeffectsofmeanstressandinclusions |
| _version_ |
1719431455375884288 |