Effect of Tape Overlap on Pressure Distribution under Compaction Roller in Automated Fiber Placement

In automated fiber placement (AFP), proper pressure distribution from the compaction roller is crucial to creating sufficient bonding between layers properly. However, certain defects can disrupt the pressure distribution. Towpreg overlap is one of the common defects, where the edge of one tape overlaps the adjacent tape, creating an uneven surface area where the roller cannot exert pressure evenly. This research investigates the influence of compaction roller stiffness and geometry on overlap handling to optimize part quality and achieve even distributed pressure. The exerted pressure from compaction rollers was evaluated using four rollers with different geometries and stiffnesses along with Finite Element Method analysis to detect each roller's pressure distribution and contact area on flat surfaces and various overlaps. The study aims to determine the ideal stiffness in both defect-free and overlap-present situations. Findings indicate that softer rollers provide greater surface coverage over overlaps but reduce pressure which can weaken the adhesion between layers, while stiffer rollers maintain higher pressure but leave large uncovered areas on uneven surfaces. The optimal stiffness range is dependent on the mold’s surface geometry, where different roller stiffness is needed for different surface geometries.