Tracing the Void Content Development and Identification of its Effecting Parameters during in Situ Consolidation of Thermoplastic Tape Material

Abstract

One of the ways to identify the quality of structures made from fibre-reinforced thermoplastic material is by examining its void content percentage. Significant improvement in mechanical properties can be achieved by minimising it. The purpose of this work was to develop a simulation tool from existing available model in literature, to trace out the void development inside the laminate during the manufacturing and identification of major influencing process parameter. The effects of consolidating force, process velocity, hot gas flow in the heating region, and repetitive passes were investigated through simulation. A series of experiments was carried out on several AS4/PEEK laminated plates manufactured by automatic tape placement process. Simulated void distribution through thickness and density were compared with measured values to trace the effecting input parameters. Thickness build-up with successive lay-ups is also monitored online and the average thickness lies in close proximity to the predicted range. Major influencing process parameters were identified.

Parametric study on processing parameters and resulting part quality through thermoplastic tape placement process

“…7,8 The verification shows a good correlation between simulation and experimental data for the void content gained using an optical analysing method. 7 The general trend of experimental and simulated data for a variation of process velocity in the range 5-9 m/min was the same, the simulation data ranges within 20% around the experimental average values and clearly with the scattering range of the experimental data. A comparable good correlation between the simulated D b and measured peel strength was found when studied for a gas volume in the range 4-12 nl/min.…”

“…Detailed explanation of the individual models and their implementation are omitted here but can be found in literature. 7,8 Standard process parameters and material Thermoplastic tape placement is available in several different set-ups: [9][10][11][12] . The placement heads are handled by gantry or by robot systems.…”

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].…”

“…The more recent development of near-infrared (NIR) diode lasers has provided an affordable, high power, reliable and controllable heat source which has enabled relatively high placement rates (100-400 mm/s) to be achieved while maintaining high levels of interlaminar bonding [1][2][3][4]. Various TP-ATP head designs have appeared in the literature and the majority of studies to date have focused on the effects of process parameters for existing placement head designs [1,3,[5][6][7][8][9][10], however little work has been published in relation to optimisation of the two fundamental aspects of the placement process (1) the distribution of heat input and (2) the consolidation pressure distribution.…”