In-situ fiber-optic temperature field measurement during thermoplastic composite welding and other applications

A sensor comprising, a fiber optic sensor comprising an optical fiber having an elongated body portion with a coating and fiber core for being a distributed sensor received in association with a specimen to be sensed, said fiber optic sensor further having a connection for being connected to an associated optical data acquisition system, whereby monitoring and diagnosis associated with such specimen may be conducted at plural locations of such associated specimen, and wherein the fiber optic sensor is embedded in the specimen comprising a thermoplastic composite welded structure, and said fiber optic sensor and associated optical data acquisition system monitors temperature distribution taken from plural locations in said specimen for in-situ fiber-optic direct temperature field measurement of said specimen,

• wherein said coating comprises an external coating of polyetheretherketone (PEEK) which can withstand heating to 610 degrees Fahrenheit;
• said fiber core has a diameter of up to 9 μm;
• said fiber optic sensor is permanently embedded in the thermoplastic composite welded structure;
• and
• said thermoplastic composite welded structure comprises two plates welded at a lap joint thereof, with said elongated distributed sensor wrapped around each respective plate and through a welding region between such two plates for simultaneous measurement of the temperature field inside the welding region and in the two plates for monitoring and inspection of the thermoplastic composite welded structure over its lifetime.