Investigation of adhesion properties in load coupling applications for flexible composites

The focus of this study is the investigation of the adhesion properties of hyperelastic fiber-matrix composites as well as the comparability of tests conducted at micro-, meso- and macro-scale. A modified fiber bundle pull-out (FBPO) test was performed to estimate the adhesion properties between fiber bundles and a hyperelastic matrix material with more realistic failure modes. This FBPO test setup provides the basis for a sufficient estimation of the interlaminar adhesion of fiber bundles along with the benefit of a faster, easier and more economic handling compared to single fiber pull-out (SFPO) tests. Two reinforcing fiber types (GF and PETF) and two hyperelastic matrix materials (PDMS and PUR) were analyzed in all combinations. Characteristic load-displacement curves were obtained during FBPO tests, showing debonding at the fiber-matrix interface. The maximum pull-out force of each fiber-matrix combination was determined to assess the adhesion properties of the flexible composites. The study reveals that a good comparability between different testing levels is given for all fiber-matrix combinations.