Modeling of Heat Transfer and Void Dynamics for the Thermoplastic Composite Tow-Placement Process

Abstract

Thermoplastic composite tow-placement technology is a nonautoclave consolidation process that offers the potential to significantly reduce fabrication costs by using in situ consolidation as a method for manufacturing large composite components. The temperature history and resulting degree of consolidation directly control the final part quality and are directly affected by the process set points. In this work, series of integrated submodels are developed for predicting the heat transfer and void dynamics within the laminate. The final through thickness void fraction is predicted as a function of process parameters. Experiments are carried out to validate these results for a wide variety of process conditions. The model is used to quantify the relationships between variation of quality of incoming material (e.g., void content ranges 3.1 and 5.5% and final void content gradients. It was found that significant gradients in final void content exist through the thickness and is directly related to processing conditions. Recommendations for process optimization are discussed.

Modeling of In Situ Strength Development for the Thermoplastic Composite Tow Placement Process

“…One of the important aspects of this process is the sequential placement of the incoming tow. Repeated passes can effectively anneal and improve the tow interface properties and help to increase final bond strength and reduce the bulk void content in the material, due to repeated compaction at the roller region [16]. The effect of multiple passes on the response of the composite material can be obtained by applying the following solution technique to the heat transfer model:…”

“…This model was validated for a wide variety of processing conditions with results from this work given in the literature [16].…”

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

“…Bonding models therefore require a detailed history of the coupled temperature and pressure history from the nip point onwards. Furthermore, other factors such as residual stress [6], void dynamics [7][8][9][10], crystallinity [11,12], and degradation [11,13] are all highly dependent on the temperature history.…”

An inverse model for optimisation of laser heat flux distributions in an automated laser tape placement process for carbon-fibre/PEEK

“…The bonding process is a combination of the flattening of the asperities at the interface (intimate contact development [11][12][13]), and the diffusion of polymer chains across the interface (autohesion or healing [14][15][16]). Other physical processes occur simultaneously during the process such as changes in crystallinity [5,17,18], void content [9,19], residual stress [20,21] and degradation [22,23] -all of which are sensitive to the specific temperature history. Optimisation of the quality of the resulting composite is non-trivial due to the multi-faceted nature of the process [22,24,25].…”