Characterisation of the shear–tension coupling of carbon-fibre fabric under controlled membrane tensions for precise simulative predictions of industrial preforming processes

A novel picture frame tester concept is introduced, allowing shear characterisation of reinforcement fabrics with both untensioned and defined membrane tension states. Reproducible preparation and handling routines are presented which kept fibre misalignments low and increased reproducibility significantly. Shear characterisations of woven fabrics are carried out with variance in magnitude, region and time of membrane tension initiation. The sensitivity of different woven fabrics to membrane tensioning is also investigated. It is found that the shear response of woven fabrics under membrane tensions is defined by the respective tension state on each axis due to the resulting normal friction forces at the crossing points. As initiated tensions on one axis are partially deflected to crossing yarns, complex tension states can be expected in the fabric. A nonlinear correlation of the global response and the initiated tension state can be observed, depending on the tension state and the woven fabric’s architecture.