Thermal response and deconsolidation of thermoplastic composite tape during pulsed flashlamp (HUMM3) heating in automated fiber placement (AFP)

Abstract

Laser heating is the most common method in thermoplastic Automated Fiber Placement (AFP) due to its precision and speed, but it poses safety and cost challenges. The HUMM3 pulsed flashlamp offers a promising broadband, programmable, and relatively safer alternative. This study investigates the thermal response and deconsolidation behavior of unidirectional carbon fiber/LM-PAEK (CF/LM-PAEK™) composite tape during HUMM3 heating in AFP. A static setup replicating AFP conditions was used to investigate the thermal response of the composite tape as a function of the programmable parameters: voltage, pulse width and frequency. Deconsolidation of the tape under HUMM3 heating was assessed from micrographs and surface topography, quantified by thickness change, void content, waviness, and roughness. Results showed that voltage is the dominant parameter influencing the thermal response, whereas pulse width and frequency showed no significant effects when total energy input was held constant. The deconsolidation analysis revealed a strong correlation of thickness change, void content, waviness, and surface roughness with local temperature. These changes are believed to be driven by polymer softening, fiber decompaction, internal gas pressure buildup, and local thermal gradients across the tape width. Compared to laser heating, HUMM3 produces less severe deconsolidation, likely due to its broadband UV–VIS–NIR spectrum enabling partial matrix absorption, reducing temperature gradients across the tape width.