Claudio Di Fratta

Fast method to monitor the flow front and control injection parameters in resin transfer molding using pressure sensors

The quality of composite parts manufactured by resin transfer molding is sensitive to material and process variations during the preform impregnation. In order to improve the process robustness in two-dimensional injection cases, this work proposes a fast method for tracking and controlling the resin flow through the preform, using only a small number of pressure sensors embedded in the mold. The approach combines pressure signals and flow modeling in a quick algorithm that returns on-line estimations of the flow front profiles. Virtual and real injection tests demonstrated the accuracy of the methodology and provided information for designing the sensing system. Moreover, the investigation proved the feasibility of a simple and effective procedure of flow rate control. Based on a computer-controlled pressure regulator acting on the inlet gate, a feedback mechanism was implemented in the system and allowed keeping the flow front velocity within a target range of values. Such a control procedure may be used to limit the formation of voids and enhance the final part quality.

Combined experimental-numerical methods to monitor liquid composite molding and characterize textile permeability

vi ity tensor through injections along only one or two textile directions, while the established characterization procedures require injections along three different directions. A comparison between the results of new and conventional approaches demonstrates that the permeability could be characterized more efficiently by the proposed methodologies, leading to a considerable reduction of time, material sample and costs.