Investigating the effect of ply orientation on the surface thermal history of newly placed tape during thermoplastic composite manufacturing with lafp process

One of the effective factors on the temperature distribution during the automated fiber placement is the thermal contact resistance. The analysis of microscopy images indicated that by changing the fiber orientation from unidirectional to cross-ply stacking sequences, the degree of intimate contact decreases. This phenomenon raises the issue of thermal contact resistance, threreby leading to the poor heat flux through the interface of the tape-substrate and the heat tends to flow to the top surface of the tape. Accordingly, in the next lay-up on the top of the previous laminate, the inlet temperature of the substrate surface for cross-ply configuration will be higher and by increasing the number of layers, more heat can accumulate on the top of the laminate. This issue highlights the importance of cooling time in cross-ply laminates, especially when the length of the domain is short or the lay-up is performed with a higher placement rate.