Glass fiber-reinforced polymer packaged singlemode - Multimode - singlemode fiber structure sensors for load/strain measurement

Conventional strain sensors such as strain gauges are widely used for measuring strain for industrial part materials that are made of glass fiber reinforced polymer (GFRP) composite. However, these sensors are vulnerable to electromagnetic interference. In this study, we implemented a singlemode - multimode - singlemode (SMS) fiber structure as a load sensor or a strain sensor for GFRP composite materials. The SMS fiber structure sensor is embedded in the surface of GFRP composites with epoxy resin. This experiment's test uses the middle and side load test and flexural strain test. The load test is carried out with middle and side load tests every 0 - 20 N with sampling every 2 N. Followed by flexural strain test in the middle section from 0 - 2.1%. From the experiment results, the optical power output of the sensor on the middle load test was nearly constant in the range of -7.5?dBm to -7.67?dBm from 0 to 18 N and decreased to -15.6?dBm at 20 N. The nearly same thing happened on the side load test. At 12 N load, the output power output was greatly decreased to -24.39?dBm. The flexural strain test also results in a nearly constant output power output in the range of -7.55?dBm to -7.89?dBm from 0 to 1.05% strain and greatly decreased to -50?dBm at 1.58% strain. The GFRP packaged SMS fiber structure sensors can measure both load and strain and can be implemented to various structural monitoring systems.