Structural health monitoring and processing of composites using photonic sensing technology

The increasing use of composite materials in many advanced structures brings with it a need to establish inspection and monitoring regimes to ensure structural integrity and safe operation throughout the service life. This results in the fast-growing composite industry searching for a technologically and economically feasible structural health-monitoring method to identify and assess defects/cracks in advanced composite structures at a very early stage of development. Optical fibre based photonic sensing technologies are increasingly common for structural health monitoring (SHM) of composite structures. In this paper, this method is used to determine the processing defects in composites effectively. In the first part of this paper, an overview of SHM for a sandwich composite specimen is presented by performing static, dynamic and low velocity impact test. Processing defects measured using embedded fibre Bragg gratings (FBGs) during automated manufacturing process of glass prepreg based composite laminates form the second part of this paper. Utilizing FBG sensors in the Automated Tape Placement (ATP), method we have demonstrated that variable parameters such as roller pressure, temperature can be measured real-time and as well as the formation of residual stresses in the fabricated laminates.