Investigation of peel resistance during the fibre placement process

In this study, the influence of compaction load, layup speed and temperature on the adhesive properties of automated fibre placement grade towpreg has been investigated on the ply-tool interface where higher peel forces are required to permit the deposition of subsequent plies. The automated layup process was simulated on a CNC milling machine, using a roller assembly and the adhesion properties of the towpreg were determined using a floating roller peel test. The processing window for the towpreg was determined using a dynamic mechanical analyser and a two-level, full factorial design of experiments was developed for the three factors, to understand their effects on the peeling force, both individually and synergistically. The design of experiments analysis indicates a strong temperature effect, with the towpregs requiring a higher layup temperature to accommodate higher layup speeds. A strong load-temperature interaction was detected, with a negative temperature effect at lower loads and a strong positive temperature effect at higher loads. The predicted factor settings to achieve a peeling force of 246 N/m are, 1 kN compaction load, 65., layup temperature, and a layup speed of 120 mm/min. Experimental tests, carried out at the predicted factor settings, agree well with the analysis, yielding a peel force of 256 N/m with a standard deviation of 25 N/m.