Press processing of functionalized flat and tape substructures with a flanged section (DediGrad)
Modern engineering increasingly relies on lightweight yet strong materials, particularly fibre-reinforced composites. Thermoplastic composites are considered especially promising because they can be efficiently manufactured, enabling faster and more sustainable production. Further strength and stiffness can be achieved when long fibre bulk materials (TBM) are combined with continuous fibre-reinforced thermoplastics (CFRTP). However, when these materials are joined, mismatched stiffness at their interface often leads to stress concentrations, which may weaken the structure.
In this project, a solution is being developed by introducing a transition zone that gradually balances stiffness between the two materials. Specially braided thermoplastic fibre tapes are being used to form this transition zone so that the strength and reliability of composite parts can be improved.
Two approaches are being investigated to achieve this goal:
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Inline grading: Local changes to fibre orientation and density are introduced during the braiding process itself. This is accomplished by adjusting the movement and geometry of the braiding tools, allowing stiffness transitions to be formed directly during production.
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Offline grading: The braided tapes are modified after production using precision laser processing. Individual fibres can be selectively cut or reshaped, and tape surfaces can be altered to fine-tune stiffness properties.
A novel Press-Through-Process (PTP) is also being tested, in which the bulk material is pressed through the continuous fibre laminate. By doing so, the braided tapes are more effectively integrated, further enhancing the transition zone.
Advanced manufacturing, mechanical testing, and imaging methods are being applied to evaluate how graded tapes influence the interface between materials. The findings will be incorporated into an empirical model, which will be used to design stronger, lighter, and more durable structural components.
Through this research, valuable knowledge is being generated for next-generation composite manufacturing. The results are expected to enable broader applications of thermoplastic composites in lightweight engineering, including automotive, aerospace, and sustainable product design.
Funded by: German Research Society (DFG)
Project partners: RWTH Aachen, TU Chemnitz, TU Wien, Fraunhofer IWU
Running time: 5/2025 – 11/2028
Contact:
© Daniel Haschock
Mr Daniel Haschock
Dipl.-Ing.
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