Effect Of Uit On Fatigue Strength Of Web- Gusset Welded Joints Considering Service Condition Of Steel Structures

• Published in: Welding in the world Vol. 56; no. 9-10; pp. 141 - 149
• Main Authors: Mori, Takeshi, Shimanuki, Hiroshi, Tanaka, Mutsuto
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.09.2012
• Subjects: Chemistry and Materials Science; Materials Science; Metallic Materials; Peer-Reviewed Section; Solid Mechanics; Theoretical and Applied Mechanics; Welded joints; Ultrasonic; Impact; Treatment; Gusset; Structure; Fatigue strength
• ISSN: 0043-2288; 1878-6669
• DOI: 10.1007/BF03321388

UIT (Ultrasonic Impact Treatment) is a method to impact on the weld toe with hard pins vibrated by ultrasonic energy, so that the improvement of the weld toe profile and the introduction of the compressive residual stress can be obtained. It is confirmed that UIT has high improving effect on fatigue strength of welded joints through many experimental researches. Those tests were conducted under low stress ratio and UIT was done in condition that specimens were not subjected to stress. When the UIT method is applied to existing structures, its effect should be verified in condition that UIT is applied under loading and fatigue tests are performed under high stress ratio. In this study, the improvement effects have been examined under such conditions. The main results obtained here are as follows. When UIT is given under no load, the remarkable effect of UIT on fatigue strength can be obtained in low stress ratio, and the effect can not be obtained in high stress ratio. When UIT is given under no load, effect of UIT becomes remarkable as the maximum stress is low and stress range is large. A remarkable effect of UIT is obtained when UIT is given under load. Especially, fatigue strength when UIT is done under the maximum load is twice or more as that of as-welded joint. The effect of UIT on the fatigue strength is mainly derived from compressive residual stress. Improvement of fatigue strength due to the modification of weld toe shape by UIT is not re-markable.