Consolidation Of Thermoplastic Composites Research Articles

Prediction of the in-plane permeability and air evacuation time of fiber-placed thermoplastic composite preforms with engineered intertape channels

The two main void removal mechanisms during vacuum-bag-only (VBO) consolidation of thermoplastic composites are through-thickness diffusion and in-plane air evacuation. The automated fiber placement (AFP) process allows for the creation of preforms with an engineered intertape channel network by deliberately introducing spacing between the tapes that can facilitate air evacuation during the VBO consolidation. However, it is unclear what dimensions of the intertape channels allow for effective in-plane air evacuation. The current research presents a predictive simulation tool to optimize the intertape channel dimensions for effective in-plane air evacuation. An analytical method is developed to calculate the in-plane permeability tensors of the composite preform with uniform intertape channel dimensions. In addition, a more elaborate mesoscale method is developed that estimates the in-plane permeability tensor of the engineered intertape channel network based on the distributions in intertape channel dimensions. Finally, a finite difference model is implemented to calculate the time required for air evacuation as a function of the in-plane permeability tensors of the preform and its in-plane dimensions. The results from the models indicated that in-plane air evacuation through the engineered intertape channel network is quick, and it takes only a few minutes to evacuate 99% of the air from large preforms like fuselage panels.

Effect of filament winding process parameters on interlaminar performance for CF/PP thermoplastic composite

This paper focuses on the in-situ consolidation process of thermoplastic composites by winding, aiming to explore the influence of key process parameters on samples’ quality. During the consolidation of thermoplastic composites, they need to go through resin melting-bonding-consolidation process, in which each parameter affects the interlaminar bond strength. Through preliminary simulation and experiments, the process parameters were selected. In this paper, wound NOL ring samples made of carbon fiber reinforced polypropylene thermoplastic composite prepregs were obtained with a hot gas assisted filament winding equipment. The influence rule of winding temperature, winding tension and winding speed on the interlaminar shear strength were analyzed based on response surface methodology. Through the analysis, in the range of the experiments winding tension and temperature had more effect on the shear strength while speed’s influence was small. With the increase of tension and temperature, the interlaminar shear strength increased, but after reaching a certain value, the laminar shear strength decreased instead.

3D Modeling of squeeze flows occurring in composite laminates

Nowadays thermoplastic composite materials are more and more used due to their specific excellent mechanical properties and a good recyclability. However, many difficulties are encountered during their forming processes, specially in the case of thermoplastic composites –TPC–. Therefore, consolidation of thermoplastic composites is becoming one of the most active research topics in composite manufacturing. Many processes proceed by heating prepregs to melt the polymer, then apply a compression in order to remove residual porosity trapped at the layers interfaces and consolidate the material. Thus the different layers containing the molten thermoplastic resin are compressed and squeeze flow occurs. Even if some modeling has been addressed, the flow occurring in the laminate, inside the yarns and in between the yarns requires rich 3D numerical descriptions with a fine enough description of the complex kinematics taking place in the laminate thickness. In this work we analyze the limits of lubrication based descriptions, justifying the necessity of proceeding with 3D descriptions. In order to alleviate the cost that such simulations involve, we employ an advanced discretization technique making use of an efficient in-plane-out-of-plane separated representation of the different fields involved in the model. Thus very fine descriptions are possible with a computational cost characteristic of 2D descriptions, as the ones making use of the lubrication hypotheses.

High temperature resistant insulated hybrid yarns for carbon fiber reinforced thermoplastic composites

ABSTRACTWith the increased use of carbon fiber reinforced composites (CFRC), the demand for the integration of insulated conductive wire/yarns in CFRC is increasing for additional function integrations such as sensoric, actoric, signal transfer, heating, etc. Between thermoset and thermoplastic matrix composites, the integration of insulated conductive materials is comparatively difficult due to the requirements of higher temperature and pressure during the consolidation of thermoplastic composites. Therefore, the need for insulating material able to withstand higher temperature for the use in thermoplastic CFRC is also high. Using DREF friction spinning technique, it is possible to manufacture yarns with a core‐sheath structure in which, as the core conductive wire/yarns and as the sheath different fiber formed materials can be used for the insulation of the core. In this study, the aspects of using different short/staple fibers such as polyester, Glass and Kynol as the sheath and the usable temperature range are revealed. Furthermore, the insulation property of such fibers after the application of different temperatures has been reported. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1179‐1184, 2013

A Multi-scale Method to Predict Residual Stress Appearance in the Process of on-line Consolidation of Thermoplastic Composites

A Multi-scale Method to Predict Residual Stress Appearance in the Process of on-line Consolidation of Thermoplastic Composites