The effect of thermal contact resistance (TCR) correlated to the degree of intimate contact (DIC) between the incoming tape and the substrate on the temperature history during laser-assisted fiber placement (LAFP) was investigated. A novel experimental methodology was designed to understand the effect with a non-contact method which did not influence the local consolidation quality. To assess the influence of TCR numerically, a three-dimensional optical-thermal model was developed. Experimental results indicated that, for the same tape temperature near the nip point, an increase in the compaction force resulted in a decrease in the temperature at the roller exit and the following cooling phase, in correlation with an increase in the final DIC. Also, the effect of the laser power on the final DIC was less pronounced than the compaction force. In the thermal model, when TCR at the tape-substrate interface was not considered, the temperature predictions underestimated the experimental measurements.

The effects of laser-induced deconsolidation on the compaction process of CF/PEEK tapes were investigated. First, tapes with different degrees of deconsolidation were manufactured using a laser heater. This procedure resulted in samples with different waviness, thickness, void content and surface roughness values. Then, as-received and laser-deconsolidated tapes were compacted under two different temperature histories and four different pressure levels. Waviness induced by laser-deconsolidation vanished when the material was heated up to the glass transition temperature even at a very low compaction pressure. Unlike waviness; increased thickness, void content and surface roughness due to laser-deconsolidation remained between the glass transition and melting temperatures. After the melting temperature was exceeded, the effects of laser-deconsolidation were dependent on the applied pressure and initial degree of deconsolidation. The final surface roughness, thickness and degree of effective intimate contact were affected by the degree of laser-deconsolidation when a compaction pressure of less than 300 kPa was applied.

Intimate contact development under LAFP-specific thermal and mechanical boundary conditions/interactions and the effect of process parameters are investigated. One-layer, unidirectional strips of CF/PEKK material were placed with different process parameters on a flat tool surface to create different intimate contact conditions. The concept of effective intimate contact, which is based on the resin content at the surface, is introduced and a methodology to measure it from surface micrographs is provided. Degree of effective intimate contact measured from the samples was compared with the existing intimate contact models. The temperature history in the compaction zone was estimated with a finite element model and pressure sensitive films were used to determine the compaction pressure. It is shown that in addition to the squeeze flow mechanism, which is the base for the current intimate contact models, through-thickness percolation flow of the resin needs to be considered to explain the effective intimate contact development.