Colloquia

Summary

Laser-assisted Automated Fiber Placement (LAFP) is a promising additive manufacturing technique that can manufacture complex structures in situ, utilizing a laser to melt thermoplastic composite tapes. It is economically beneficial because it eliminates the time-consuming and energy-intensive autoclave consolidation process. A critical component of the LAFP process is the elastomeric compaction roller, which applies pressure to the tapes over a contact area, effectively consolidating them. Since the roller operates under high cyclic pressure and temperature loads, it loses function at a rapid rate, requiring frequent replacements. Further, the design parameters of the roller affect the consolidation pressure distribution and thus understanding the effect of these parameters is important to understand the LAFP process itself.

The current study is conducted with two objectives: 1) Research on the underlying cause of loss of function, and 2) To investigate how different elastomer materials, elastomer thicknesses, and applied forces affect the roller pressure distribution. Roller degradation was studied by performing several experiments, including microscopy, Thermogravimetric analysis (TGA), and Fourier Transform Infrared Spectroscopy (FTIR). The cause of the roller function loss was found as a combination of wear mechanisms. To study the effect of design parameters, an FE model of the elastomeric roller was developed. Hyperelastic stress-strain behaviour in various strain modes of multiple materials were characterized and were used as material models in FE analysis. The results of FE analysis showed that, using a more compliant material results in an increased contact length at a comparable contact pressure. However, an increase in contact length can result in accelerated wear. Other important factors on the roller design were found to obtain higher contact lengths and more even pressure distribution. The FE model was validated by performing pressure distribution tests.

The study highlights the complex nature of the contact in the consolidation roller in the LAFP process. Future research could be directed to further understand the contact mechanics and explore the possibilities to help improve the productivity and roller lifetime.