Investigation of the compaction behavior of uni- and bidirectional non-crimp fabrics

The through-thickness compaction behavior of engineering textiles significantly influences the resulting component properties during liquid composite molding processes (LCM). It determines the final fiber volume content and thus the necessary press force, the permeability as well as the final mechanical properties. In the present work, the behavior of a uni- and bidirectional carbon fiber non-crimp fabric (UD- & Biax-NCF) with the same fiber type and areal density of fibers in the respective main reinforcement directions is tested in a punch-to-plate setup. Thereby, the influence of the relative fiber orientation at the interfaces of a layup as well as the number of plies is investigated. A combined influence of roving nesting and superposition of stitching patterns is observed. This results in a common influence of decreasing resistance to compaction for higher numbers of layers, while the relative orientation of the interfaces in a layup is only significant for the Biax-NCF.