NAS1581 Flush Head Bolts loosen on Aircraft External Fairing

[Wingtip46]

What is the mechanism by which a bolted joint carrying shear loads ( no imposed tension or compression) can loosen?....Joint is held together by bolt clamp-up and fastener is not an interference fit to the hole....

 

[CoryPad]

Two recent journal articles have addressed this issue. One is from Pai and Hess in Engineering Failure Analysis 9 (2002) 383-402. It states that complete or localized slip at thread and head contact surfaces results in loosening. The other article is from Jiang et al. in Journal of Mechanical Design v125 (2003) 518-526. It states that local cyclic plasticity occurs in the roots of engaged threads and leads to loosening. These are journals that are available from university engineering libraries, so contact your nearest one for help. Or, you could download them for a fee from:

ScienceDirect for Engineering Failure Analysis

http://www.sciencedirect.com

The American Society of Mechanical Engineers for Journal of Mechanical Design

http://www.asme.org

Regards,

Cory

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