Chara-TPC – Establishment of a characterization center in RLP for thermoplastic composites

Composites with a thermoplastic matrix, so-called thermoplastic composites (TPC), are increasingly used in key industries due to their lightweight construction potential. Thanks to their remeltability and short cycle times, they offer the opportunity to make an important contribution to the environmental compatibility and competitiveness of new products. Continuous fiber-reinforced thermoplastic composites (eTPC) are playing a special role. Due to their excellent mechanical properties, they are particularly suitable for use in structural load-bearing components. Obstacles to application are the frequent lack of fully comparable and efficiently calculated material properties for complex load cases. However, these are relevant for the component design.

The goal of Chara-TPC project is developing new, efficient characterization methods for complex loading cases of eTPC for generating comparable material properties. This allows the mechanical potential of this material class to be fully exploited and the hurdles for a large series application to be lowered.

During the project period from January 2020 to December 2022, methods for the characterization of short-term dynamic, multi-axial and long-term loads of high performance components out of eTPC as well as joints of hybrid components with eTPC were developed. In a step preceding the methods development, the production of plates in a static pressing process, the production of tube specimens in an innovative tape laying process and the preparation of specimens with regard to efficiency and quality were also investigated (Figure 1).

Milestones of the project were the development of a quasi-static hot pressing process for the near-series production of eTPC plates on a laboratory scale and the influence of the surface roughness of machined specimen edges on matrix-dominant mechanical properties. In the field of short-term dynamic testing, a new tapered specimen geometry for the determination of tensile properties without load introduction elements was developed (Figure 2 left). In the crash loading case, the development of a crash-stable specimen that provides geometry-independent energy absorption values was pursued (Figure 2, right). A further milestone was the test methodology developed for the multi-axial loading case on tube specimens (Figure 3). By analyzing the eTPC fracture body and its influencing parameters, a methodology was defined that reduces the characterization effort by 61% while maintaining the same characterization quality. A glass fiber reinforced polypropylene (GF-PP) and a carbon fiber reinforced polycarbonate (CF-PC) tape material were used to experimentally validate each of the developments.

The methods developed are now finding their way into industrial application via workshops and training courses.

The project „Chara-TPC – Establishing a material characterization center for thermoplastic composites (TPC) in Rhineland-Palatinate“ is funded by the European Regional Development Fund (ERDF) and the Ministry of Economics, Transport , Agriculture, and Viticulture (MWVLW; Funding reference: 84005413).