Thermal modelling of the laser-assisted thermoplastic tape placement process

Abstract

Thermoplastic tape placement opens the possibility of a fully automated composite production. The resulting quality is highly dependent on the thermal history during consolidation. This article focuses on the thermal modelling of a tape placement system employing a nearinfrared laser. A nonlinear two-dimensional finite element model is presented for a carbon fibre reinforced thermoplastic (AS4/PEEK) composite placement process using a conformable roller. The relative influence of roller geometry, roller temperature and thermal contact resistance was studied. Temperature measurements were performed using thermocouples welded to the substrate. The model predictions show good correlation in terms of timing of the irradiation, shadow and consolidation regions. The roller temperature was found to have the most significant impact on the bond line temperature distribution.

A combined optical-thermal model for near-infrared laser heating of thermoplastic composites in an automated tape placement process

“…A consequence of this geometry is the curvature of the tape prior to the nip point blocks the laser beam from directly irradiating the substrate and tape immediately before the nip point, potentially creating a shaded region [15]. Previous studies suggest that a significant temperature drop would occur, adversely affecting the bond quality [14,15]. It is possible that the high angles of incidence would cause significant reflections that would result in indirect irradiation of the shaded areas.…”

“…In ATP, the laser optics must be mounted above the plane of placement to provide adequate clearance from the tooling. A consequence of this geometry is the curvature of the tape prior to the nip point blocks the laser beam from directly irradiating the substrate and tape immediately before the nip point, potentially creating a shaded region [15]. Previous studies suggest that a significant temperature drop would occur, adversely affecting the bond quality [14,15].…”

“…Current temperature control technologies for laser-assisted TP-ATP are based on non-contact temperature measurements of the tape and substrate prior to the nip-point. The correlation between the pre-nip-point and consolidation temperature is not well understood, and previous work suggests that significant temperature drop would occur due to shadows on the tape and substrate immediately prior to the nip point [14,15]. A well formulated thermal model will give valuable insight into the process behaviour as well as a tool for optimisation of the thermal history.…”

Automated manufacturing of composites

“…Heating: for thermoplastic composites, intense heating needs to be done at the NIP area. Heating is usually done using a hot gas (nitrogen) torch, or a laser [10,11]. For machines using the hot gas torch, the temperature at the nozzle o C. This temperature can drop significantly at the NIP point.…”

New analytical and numerical optical model for the laser assisted tape winding process

“…It should be noted that the aforementioned optical models deal with flat substrates only. Apart from employing an optical model, several researchers assumed a uniform heat flux distribution without considering the reflections of the laser light [8][9][10].…”