Monitoring of bolt clamping force at high temperatures using metal-packaged regenerated fiber Bragg grating strain sensors

Abstract

Insufficient or excessive preload has been regarded as the main issue that may endanger the safety of bolted joints operated at high temperatures. A new technique for monitoring the bolt clamping force is thus proposed using metal-packaged regenerated fiber Bragg grating (RFBG) strain sensors spot-welded onto the bolt. The measurement of the clamping force in a bolted steel-steel joint subjected to thermal loading is conducted. The experimental results show that the bolt clamping force can be monitored by the metal-packaged RFBG strain sensor at high temperatures up to 500 °C. This technique provides a new possibility for structural health monitoring of bolted joints operated at high temperatures.