SENS4COM

Advanced manufacturing of composite materials using smart optical fiber sensors

Composite materials are more and more present in aerospace, defense and automotive applications that are asking stronger, lighter and safer materials. They bring unique advantages over traditional materials such as high stiffness, high strength, low density, long fatigue life, among others. Composite material pieces of ever-growing complexity and functionality are produced, requiring monitoring means to optimize their production and lifetime. Quality control during the production process (autoclave or Resin Transfer Molding (RTM)) is a real added value. Manufacturers usually do extensive non-destructive testing (NDT) on a part of their production to attest of its quality, which costs both time and money. There is no doubt that the in-situ monitoring of the production process will greatly enhance the production yield, quality and lead time of manufactured parts. Also, for the design of new pieces, a better knowledge of the real temperature and strain profiles and their location will allow to carry out fast and adapted feedbacks both at the design stage to reduce the number of prototypes during the development and during the production to limit the number of rejected parts. This would significantly reduce the access time to the market.

Optical fiber sensors, specifically fiber optic configurations which include Fiber Bragg Gratings (FBGs) are particularly relevant. Tiny FBG sensors embedded in a composite material can provide in situ information about polymer curing (strain, temperature) in an elegant and nonintrusive way. In addition to the intrinsic sensitivity to temperature, pressure and axial strain, FBGs yield a wavelength-encoded response, which can be easily recorded and processed. Several tens of sensors can be distributed in a single optical fiber and interrogated simultaneously.

FBG read-out equipment, often referred to as interrogators, are currently available on the market but are too expensive to make FBG sensors commercially viable during the composite manufacturing process. B-Sens and Somni will team up to design arrays of FBG sensors to be embedded in composite materials and build a cost-effective interrogator that will be fast enough to fulfill a double objective: (1) monitoring of the fabrication process by measuring the temperature and stress profiles inside the composite materials and (2) detection of cracks in the composite materials during their use. The interrogator will carry the relevant information to the end-user. It will be tested on field at Sonaca. Hence, the FBG technology will be deployed to the IoT sphere, rendering smart the manufacturing process of composite materials and their subsequent use in aerospace applications.

Vertical sector addressed

•  Healthcare

Industrial application addressed

• Predictive maintenance
• Monitoring & control

Technologies involved

• IoT & wearables
• Simulation & modelling