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An Experimental and Finite Element Study of Fatigue Behaviours of Welded Armor Plate Joints.

Record Type:	Electronic resources : Monograph/item
Title/Author:	An Experimental and Finite Element Study of Fatigue Behaviours of Welded Armor Plate Joints./
Author:	Sinnott, Daniel J., II.
Description:	1 online resource (166 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 84-01, Section: B.
Contained By:	Dissertations Abstracts International84-01B.
Subject:	Materials science. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=29274868click for full text (PQDT)
ISBN:	9798438772996

An Experimental and Finite Element Study of Fatigue Behaviours of Welded Armor Plate Joints.
Sinnott, Daniel J., II.

An Experimental and Finite Element Study of Fatigue Behaviours of Welded Armor Plate Joints. - 1 online resource (166 pages)

Source: Dissertations Abstracts International, Volume: 84-01, Section: B.

Thesis (Ph.D.)--University of Michigan, 2022.

Includes bibliographical references

Readiness is a key area of focus for the U.S. Army. The Ground Vehicles Systems Center (GVSC) in Warren, Michigan has been investigating various performance parameters of welded structures in armored vehicles. Of these parameters, the fatigue of welded vehicle structures is of unique interest. Cyclic fatigue damage incurred during normal operation can lead to additional maintenance or structural failure, severely limiting vehicle availability. A better understanding of the fatigue parameters of welded armored vehicle structures is of great value to the U.S. Army in order to maintain readiness. This research was proposed to directly study the fatigue parameters of relevant base-filler combinations for GVSC by fatigue testing welded specimens. This approach allows for a comparison between the fatigue characteristics of welded armor steels to common welded ferritic and stainless steels that are seen in civil structures. In addition, the Master S-N curve approach used here provides a better method for analyzing fatigue performance across differing combinations of base metal and weld filament, allowing for a more robust study of the effects of material selection. The GVSC provided fatigue testing equipment and hundreds of welded armor steel specimens consisting of relevant base metal and weld material combinations for study. These specimens were fatigue tested over a period of several years. Finite element models simulating the test specimens were generated to determine the structural stresses experienced by each welded sample during fatigue testing using a novel mesh-insensitive method. These structural stresses can then be transformed into equivalent structural stresses by including the relevant bending ratio and thickness effects of the tested specimens themselves. These equivalent structural stresses can be used in conjunction with the experimentally determined fatigue lives of the tested welded specimens to plot fatigue results on the Master S-N curve for ferritic and stainless steels. These results can be compared to the expected mean Master S-N curve to determine agreement with ferritic and stainless steels as well as compared to each other to examine what effect, if any, base or filler selection had on fatigue performance. In total, 47 welded specimens with a 1:1 width-to-thickness ratio and 19 welded specimens with a 5:1 ratio were fatigue tested and analyzed using the Master S-N curve method. Based on the results, it does not appear that welded armor steels behave differently than common ferritic and stainless steels seen in civil structures. Over 92% of the tested specimens were within two standard deviations of the mean Master S-N curve. The 1:1 ratio welded strips had a vertical shift from the mean curve due to the lack of residual stresses from their small width-to-thickness ratio. The 5:1 ratio specimens had excellent alignment with the mean Master S-N curve, showing the importance of ensuring residual stresses for fatigue analysis. It was found that the selection of base metal or weld filament had very little effect on the fatigue life of the welded test specimens when using survival statistics to examine the test data results. Rather, the presence of welding-induced distortion was the only variable that was shown to have a significant effect on the fatigue behaviors of welded armor joints. Ensuring sufficient weld quality is therefore more valuable for improving the fatigue parameters of welded armor plate joints than the choice of base metal or weld filament for armored vehicle structures.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9798438772996Subjects--Topical Terms:

543314
Materials science.
Subjects--Index Terms:

Fatigue behaviorsIndex Terms--Genre/Form:

542853
Electronic books.

An Experimental and Finite Element Study of Fatigue Behaviours of Welded Armor Plate Joints.
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520 $a Readiness is a key area of focus for the U.S. Army. The Ground Vehicles Systems Center (GVSC) in Warren, Michigan has been investigating various performance parameters of welded structures in armored vehicles. Of these parameters, the fatigue of welded vehicle structures is of unique interest. Cyclic fatigue damage incurred during normal operation can lead to additional maintenance or structural failure, severely limiting vehicle availability. A better understanding of the fatigue parameters of welded armored vehicle structures is of great value to the U.S. Army in order to maintain readiness. This research was proposed to directly study the fatigue parameters of relevant base-filler combinations for GVSC by fatigue testing welded specimens. This approach allows for a comparison between the fatigue characteristics of welded armor steels to common welded ferritic and stainless steels that are seen in civil structures. In addition, the Master S-N curve approach used here provides a better method for analyzing fatigue performance across differing combinations of base metal and weld filament, allowing for a more robust study of the effects of material selection. The GVSC provided fatigue testing equipment and hundreds of welded armor steel specimens consisting of relevant base metal and weld material combinations for study. These specimens were fatigue tested over a period of several years. Finite element models simulating the test specimens were generated to determine the structural stresses experienced by each welded sample during fatigue testing using a novel mesh-insensitive method. These structural stresses can then be transformed into equivalent structural stresses by including the relevant bending ratio and thickness effects of the tested specimens themselves. These equivalent structural stresses can be used in conjunction with the experimentally determined fatigue lives of the tested welded specimens to plot fatigue results on the Master S-N curve for ferritic and stainless steels. These results can be compared to the expected mean Master S-N curve to determine agreement with ferritic and stainless steels as well as compared to each other to examine what effect, if any, base or filler selection had on fatigue performance. In total, 47 welded specimens with a 1:1 width-to-thickness ratio and 19 welded specimens with a 5:1 ratio were fatigue tested and analyzed using the Master S-N curve method. Based on the results, it does not appear that welded armor steels behave differently than common ferritic and stainless steels seen in civil structures. Over 92% of the tested specimens were within two standard deviations of the mean Master S-N curve. The 1:1 ratio welded strips had a vertical shift from the mean curve due to the lack of residual stresses from their small width-to-thickness ratio. The 5:1 ratio specimens had excellent alignment with the mean Master S-N curve, showing the importance of ensuring residual stresses for fatigue analysis. It was found that the selection of base metal or weld filament had very little effect on the fatigue life of the welded test specimens when using survival statistics to examine the test data results. Rather, the presence of welding-induced distortion was the only variable that was shown to have a significant effect on the fatigue behaviors of welded armor joints. Ensuring sufficient weld quality is therefore more valuable for improving the fatigue parameters of welded armor plate joints than the choice of base metal or weld filament for armored vehicle structures.
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