Tack of Thermoset Impregnated Carbon Fibers (TackTIC) – Characterization and Modeling of Prepreg-Tack for the Automated Production of CFRP Structures

• Applicant: Professor Dr.-Ing. Dieter Meiners
• Subject Area: Polymeric and Biogenic Materials and Derived Composites ; Plastics Engineering
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 458900231

In terms of process stability and final laminate quality of large high-performance structural parts, the stickiness (tack) of prepregs is considered the crucial material property for the success of automated lay-up processes such as automated fiber placement (AFP) and automated tape laying (ATL). Along the lines of industrial practice, scientific research has mainly focused on the investigation of the influence of parameters which can be adjusted directly in the production process. Influences of the production environment as well as the material properties itself are neglected resulting in nescience of the fundamental mechanisms and the complex interaction that govern prepreg tack. The scope of the research project, therefore, is the acquirement of a comprehensive state of knowledge on the influences and effect mechanisms of prepreg tack and its modeling. The developed material model enables the prediction of quantitative tack properties based on material characteristic values, production-relevant environmental influences and process parameters. For this purpose, the complex contribution of adhesive and cohesive portions to prepreg tack are regarded by implementing rheological and structural aspects as well as cure kinetics and the interface formation towards different contact materials. In order to achieve the project goal, two measurement methods for quantitative tack characterization, namely a probe and a peel tack test, are developed, implemented and evaluated comparatively. The methods are put into practice by investigating the influence of process (temperature, compaction force, dwell time, separation speed and material combination) as well as environmental parameters (material ageing and humidity-controlled conditioning) on tack experimentally. The findings for the tack properties of three formulated epoxy resins and one commercial prepreg are assisted by material data obtained from ageing, conditioning, thermal, structural and chemical analysis on the prepreg material and finally merged in the tack model.

• DFG Programme: Research Grants