Development and verification of self-sensing structures printed in additive manufacturing: a preliminary study

Additive Manufacturing (AM) is used today to fabricate complex structures as well as to demonstrate innovative design concepts. This opens new horizons in the field of Structural Health Monitoring (SHM), allowing to correlate a high performing design with real-time detection and identification of the structural damage. Fiber optical sensors, such as Fiber Bragg Gratings (FBGs), are an effective option for this type of applications. The present work discusses the development of a demonstrative self-sensing structure, obtained by embedding a FBG sensor during the 3D stereolithographic (SLA) printing process. The paper reports the strategies developed in order to ensure a correct adhesion of the FBG sensor embedded into the structure and the experimental tests used for validating the structural response of the self-sensing specimen. The output signal of the FBG sensor was continuously recorded during the different stages of the creation phases: this allowed real-time monitoring of the whole AM process (i.e. printing, washing and curing stages). The obtained results showed that the self-sensing demonstrative structure was able to effectively monitor the thermo-mechanical behavior of the AM process and to guarantee the correct identification and measurement of the strain as the same structure was subjected to a controlled stress.