Geometrical discontinuity as a consequence of essential hole drilling operation in bolted joints results in stress concentration and thus increases the tendency of fatigue crack to initiate and grow under cyclic loading. However, due to ease of assembling and possibility of dismantling, these connectors have excessive use in aerospace constructions. Therefore, it is of great importance to reduce the effect of the stress concentration and attain enhanced fatigue life. This can be achieved by introducing a compressive stress field into the surrounding material of the hole. One common technique is hole cold expansion that was originally invented by Boeing company about forty years ago and later developed and marketed by Fatigue Technology Inc. . Cold expansion literature has been generally devoted to open hole specimens. Nevertheless, cold expanded specimens are practically used in bolted and riveted connections possessing different fatigue behavior than open hole specimens. This paper has sought to investigate the fatigue behavior of cold expanded specimens after being subjected to bolt tightening. Fatigue tests and numerical simulation were conducted to study the role of bolt clamping force on the residual stress distribution, fatigue life and failure mode of bolted cold expanded specimens. The results significantly reveal that bolt clamping contributes more positive effect and prolongs the fatigue life additionally. However, it may also change the failure mode from notch fatigue to fretting fatigue.
On the fatigue behavior of cold expanded fastener holes subjected to bolt tightening
International Journal of Fatigue ; 33 , 6 ; 800-810
2011
11 Seiten, 10 Bilder, 4 Tabellen, 42 Quellen
Aufsatz (Zeitschrift)
Englisch
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