Photoinduced grating-based optical fiber sensors for structural analysis and control

Optical fiber sensor-based instrumentation has been shown to be extremely attractive for the in situ health monitoring, diagnostics and control of civil infrastructure. This paper presents the design, fabrication and implementation of long-period grating (LPG) based optical fiber sensors for the nondestructive evaluation of smart structure systems. The LPG sensors, fabricated in standard SMF-28 Coming fiber, were attached to pieces of rebar and cyclically loaded from no-load through 35 kN loads; sensor performance was monitored using an optical spectrum analyzer, A mechanical extensometer was collocated with the LPG sensor for comparison, Short-period optical fiber Bragg grating (FBG) sensors were also tested under similar conditions. Sensor performance for both the LPG and the FBG was found to be consistent with strain measurements using the extensometer. (C) 1997 Elsevier Science Ltd.