Fraunhofer Institute for Production Technology IPT
New winding concepts
Pressure vessels are used to store hydrogen and other gases or liquids. The components are manufactured in a winding process in which the base body of the tank is wrapped in thermoplastic tape. The "HoliCPV" research project is concerned with the software-based optimization of the winding process using a toolchain that links all development stages of the pressure vessel.
Research project "HoliCPV"
Networked development tool for thermoplastic pressure tanks
To achieve the goals of the European Green Deal and the German government's national hydrogen strategy, industry must develop sustainable production facilities for hydrogen components and systems. Efficient processing of sustainably produced materials is therefore a goal of all industrial production concepts of the future.
Pressure tanks that serve as hydrogen storage tanks are traditionally made from thermoset, fiber-reinforced plastic (FRP). However, this class of material cannot easily be processed and cannot be recycled. In the "HoliCPV" research project, a project consortium led by Fraunhofer IPT is researching how to sustainably process thermoplastic carbon fiber-reinforced plastics (CFRP). Thermoplastic FRPs are recyclable and offer advantageous material properties in the manufacturing process. To date, however, there are no software solutions for web planning, design and process modeling to exploit the advantageous processing possibilities of thermoplastic tapes. In the "HoliCPV" project, the partners are developing a networked toolchain for pressure vessels made of thermoplastic fiber-reinforced plastic. The toolchain is a software development tool that links all the process steps involved – from component design, path planning and FE analysis to process evaluation and documentation. On this basis, it can be used to derive an optimized winding strategy for thermoplastic pressure tanks.
Discontinuous winding saves material
The use of the thermoplastic material has two advantages: less material needs to be used for the same strength. This reduces the overall weight of the pressure tank and CO2 can be saved while the tanks are in use. While only geodesic tracks can be used for dome wrapping in conventional thermoset winding processes, thermoplastic tapes can also be deposited in non-geodesic tracks. In addition, the tape can be cut and repositioned during the deposition process. This allows fixed areas of the print tank to be reinforced locally without having to completely wrap the tape around the tank.
Deriving a process model for thermoplastic tape winding
Software solutions for the design and process simulation of pressure tanks already exist for the established winding of thermoset materials in continuous, geodesic paths. For tape winding with thermoplastic material, such a toolchain, which takes alternative path planning into account, has yet to be developed. Exactly this is being done in the "HoliCPV" project.
The new toolchain provides interfaces between path planning, FE model and process model in order to optimally coordinate the developmental steps of component design and process development. During the manufacturing process, sensors record the process data, which is stored in a digital twin. This data is then used to identify deviations between the model data and the real component. In addition, the data collected during the process can be fed back into the FE model in order to evaluate the deviations.
Recycling thermoplastic tapes
When the thermoplastic pressure tank has reached the end of its service life, the thermoplastic tape can be removed from the liner (the base body of the tank) in an unwinding process and recycled into a high-quality, continuous fiber-reinforced semi-finished product. This is done without dissolving the fiber-matrix composite. The recovered tape can be reused for new components. Fraunhofer IPT already demonstrated the feasibility of this recycling process in an earlier research project called "Tankcycling." The digital toolchain helps determine the path planning for the recycling process by using the digital twin.
Project partners
- AVANCO COMPOSITES GmbH, Herford
- Fraunhofer IPT (Coordinator), Aachen
- IDVA GmbH, Freiburg i. Br.
- Module Works GmbH, Aachen
Funding
The "HoliCPV" research project is funded by the Federal Ministry of Economics and Climate Protection (BMWK) as part of the "Lightweight Construction Technology Transfer Program."
Funding reference: 03LB3101A