Interaction of process parameters and material properties with regard to prepreg tack in automated lay-up and draping processes

Selectively adjusting the tackiness of epoxy pre-impregnated carbon fibers is considered mandatory in terms of process stability of automated lay-up and draping. This experimental study investigates the influence of crucial process and material parameters such as temperature, compaction force, debonding rate and ageing on prepreg tack using a rheometer as a test apparatus. Accompanying material characterization is conducted in terms of cure kinetics and rheology to establish a profound understanding of tack-determining mechanisms and material behavior. Two evaluated tack indicators are found to be sensitive to temperature and steadily increased as a function of compaction stress. The maximum tack plateau of progressively aged prepreg shifts towards higher temperatures. Material is still processable after tack life with tack properties exceeding the adhesive performance of fresh prepreg when being processed at elevated temperatures. Tackiness of impregnated tape for automated draping and aerospace epoxy prepreg differs in both quantitative extent and pivotal mechanisms.