Consolidation of hybrid textiles

Figure 1: Picture of a partial cutaway of quasi-UD / PEI hybrid textile manufactured at the Faserinstitut Bremen

Technologies

• Fibre-reinforced plastics
• Hybrid textiles
• Press moulding
• Analytical modelling
  

Background

Fibre-reinforced thermoplastic composites are materials with excellent mechanical properties ideal for lightweight applications. As of today, their production mainly is based on expensive pre-impregnated materials with which limited part complexity can be attained.

Press moulding of hybrid textile is an alternative process in which semi-complex shapes can be produced. Hybrid textiles have good drapeability and an elevated design freedom, as many parameters can be easily and locally changed. A three-dimensional consolidation model would allow to avoid defect formation and enable process and design optimization. However, such a model is currently lacking.

Goals

The main goal is to develop a three-dimensional consolidation model. In a first step, a “standard” consolidation model is developed and experimentally validated with thorough experiments. A collaboration with the Faserinstitut Bremen (FIBRE) in Germany allows to extent the investigations to high-performance materials: carbon fibres and polyetherimide (PEI). The consolidation model then has to be extended in three dimensions. Finally, demonstrator parts are produced to highlight the potential of this technology, especially for semi-complex shapes.

Results

A novel consolidation model was developed, in which air entrapment, dissolution and diffusion in the molten polymer are considered. A set of experiments was designed to compare the measured impregnation degree against the model predictions and good agreement is found at different pressures and for two different polymers, polypropylene and high-density polyethylene as shown in Figure 2. Further experiments are being currently carried out with the carbon and PEI hybrid textile shown in Figure 1. In the next work steps, the consolidation model will be extended in three dimensions and validated experimentally.

Figure 2: Measured impregnation degree in function of the time along with the predictions of the proposed model with PP as matrix on the left and HDPE on the right.

Publications:

• Werlen V., Vocke R., Schwanemann P., Michaud V., Brauner C., Dransfeld C., Rytka C. Consolidation of hybrid textiles for aerospace applications. 20^th European Conference on Composite Materials ECCM20, Lausanne, CH, 2022.
• Werlen V., Vocke R., Schwanemann P., Michaud V., Dransfeld C., Rytka C. On the impregnation of hybrid textiles during press moulding and why entrapped air matters. To be submitted to Composite Part A end of 2022.
• Werlen V., Vocke R., Rytka C., Schwanemann P., Michaud V., Dransfeld C., Brauner C., Herrmann A. S. ConThP: Consolidation of thermoplastic hybrid yarn materials. 5^th International Conference and Exhibition on Thermoplastic Composites ITHEC, Bremen, DE, 2020.