1710 Monitoring of Mechanical Joint Structure by the Smart Bolt

In aircraft structures, the weight reduction is severely demanded. Recently a lot of components became manufactured by composite materials. Consequently, there exist many fastener joints that are joining a metal and composites parts. In order to keep high reliability of aircraft structures, it comes more important to make clear about the mechanical behavior of composite/metal joint portions. Authors have proposed a "smart bolt", in which an embedded optical fiber sensor achieves a functionality of monitoring the mechanical conditions at fastener joints by using it. The tensile tests of the composite/metal multiple-row joint structure were conducted to assure the applicability of smart bolt for practical structure. And results are summarized as follows: (1) The details of mechanical behaviors at fastener joint were successfully monitored even in the multiple-row joint. (2) A monitoring functionality of abnormalities of a multiple fastener joint was demonstrated by the case in which an adjoining bolt was lost.