Integrated Sensors for Monitoring the Production of CFRP Aerospace Structures
Fraunhofer LBF and MT Aerospace are integrating glass fibre sensors into thick-walled CFRP structures. They monitor the flow front during vacuum infusion, thereby helping to increase process reliability.
MT Aerospace manufactures large aerospace components such as booster housings made from carbon fibre reinforced plastic (CFRP) using the vacuum infusion process. This is where a dry-wound blank is infiltrated with resin in a vacuum bag whilst slowly being turned in an oven. In order to monitor the flow front of the inflowing resin, the project partners have now introduced glass fibre sensors to the component during the winding process. During the subsequent infusion, the flow front and the resin distribution can be monitored using the embedded optical sensors. The flow front is the line where the resin first comes into contact with the dry fibres.
Representation on a digital twin
The signals from the rotating part in the oven are sent to an external computer for the process monitoring of the digital flow front recognition. A digital representation of the sensor position on the component then shows when the flow front has reached the sensor. According to Fraunhofer LBF, this manufacturing technology makes previously hidden processes visible and allows them to be monitored digitally, which increases process reliability. It also enables the resin flow to be made automatic, meaning the product can be manufactured multiple times at a consistent quality. It is hoped that this will also allow interventions during the manufacturing process. The developers anticipate the integrated sensors to be used in many other areas in the future, such as in Industry 4.0-compliant automated control of manufacturing processes and for monitoring the structure of components right from the earliest life cycle phase.