Monitoring of Bolt Loosening in Metal/Composite Multiple-Row Shear Fastener Joint using Smart Bolt

Abstract

As a monitoring instrument of the mechanical conditions at composite/metal shear fastener joints, a "Smart bolt" embedded optical fiber sensor was proposed. In addition, it was shown that, by applying Smart bolt to the single-row fastener joint specimens, the mechanical behaviors and the early stage of damage of composite around the bolt hole can be monitored. In this study, Smart bolt was applied to the composite/metal multiple-row joint specimen of in-line array and the tensile tests of the joint specimen with looseness of one fastening bolt were conducted. Through the test results, it was demonstrated that the mechanical behaviors at fastener joint are successfully monitored also in the multiple-row fastener joint and the loosing case of fastening bolt around Smart bolt can be detected.