On the Characterization and Modeling of Interfaces in Fiber Reinforced Polymer Structures

Fiber reinforced polymers offer a wide range of advantageous characteristics, reaching from the high cost-efficiency of discontinuous fiber reinforced polymers used for semi-structural components to the ultra-high strength of continuous fiber reinforced polymers used for high-performance lightweight components. A new hybrid material class aims to combine the specific advantages of continuous and of discontinuous fiber reinforced polymers. Here, continuous fibers reinforcing the main load paths of a discontinuous long fiber composite component allow for cost-efficient, yet high-performing and lightweight fiber reinforced polymer structures. Such continuous-discontinuous long fiber reinforced polymer structures possess a wide range of internal interfaces, which highly affect the structure's fracture behavior. In order to characterize and model such interfaces, appropriate methods are developed and applied to the materials and manufacturing processes specific for this novel material class. Both fiber-matrix interfaces and lamina interfaces are examined experimentally and further analyzed numerically considering three different scales of interest as well as the material's microstructure.