Published on 18 April 2018
TWI is working to develop an online monitoring system for the manufacture of composite materials using the Resin Transfer Moulding (RTM) process. The RTM process is mostly used in aeronautical, automotive and wind energy applications, such as the manufacture of wind turbine blades. The process ensures the reduction of mass and the increase of operating life without compromising on performance. Online monitoring of the process is proposed to provide an estimation of the component’s state and to predict defects.
TWI is involved in the SimCoDeQ project, which is part of a Clean Sky research program and consists of three main partners directed by a Topic Manager. The overall concept addresses the development of a stochastic simulation tool, which will be implemented on a pilot RTM line, where evaluation and NDT demonstration runs will take place.
Why process monitoring?
The variable character of materials, process conditions, and geometries add challenges for monitoring and predicting the behaviour of the system. The control of the process has been presented for both the impregnation phase and the resin cure stage of RTM in laboratory scale. However, a robust sensing system, numerical simulation software, and a flexible injection system are mandatory in order to develop an adequate control system for the RTM process. TWI is focusing on the development of a process monitoring system with the use of dielectric sensors, which appears to be the most promising and popular methodology for monitoring the resin state in composite materials manufacturing.
Objectives
The main project’s objectives were as follows:
- Development of a flexible dielectric sensor for the resin flow during the RTM process. The analysis and optimisation of sensor geometry and materials will increase the detectability in the challenging case of carbon fibre materials.
- Characterisation of the defects related to the flow and prediction of resin flow disturbances, which lead to the creation of dry spots and voids.
- Examination of other sensing methods, such as thermocouples and pressure transducers, for the monitoring of the process.
Manufacturing insights
This project contributes to transforming the detection methods for composite materials manufacturing with the development of a predictive tool for defects.
The real-time information of the composite’s state could potentially reduce the defects related to resin flow during the process. The improvement of the part’s quality reduces wastage and the production costs.
In this study, an L-Shape mould was selected for the development of the monitoring system, which is presented in Figure 1. Integrating the sensors to the process is one of the main challenges related to the interaction of the system with the composite part.
The next steps
Future work includes the following:
- Optimising dielectric sensor geometry with the use of finite elements methodology.
- Increase sensor sensitivity and reduce intrusiveness to the process with smart packaging techniques.
- Develop an algorithm which updates the stochastic simulation tool with the flow speed and direction.
- Characterisation of the defects and comparison of the NDT evaluation with the stochastic tool.
Find out more
To find out more about our work on this project, contact us
Acknowledgments:
This research project has received funding from the Clean Sky 2 Joint Undertaking under the European Union’s Horizon 2020 research and innovation programme under grant agreement No 686493.