Continuous monitoring of three-dimensional resin flow through a fibre preform

A basic requirement for an accurate numerical simulation of the resin transfer moulding process is a set of exact permeability coefficients of the applied textile reinforcement. The permeabilities are usually obtained from the measurement of flow front propagation through a stack of planar fibre preforms. While measuring the in-plane flow is considered as rather simple, the detection of a flow front that moves perpendicular to the laminate plane emerges to be difficult. Therefore, the knowledge of the transverse impregnation behaviour is still sparse and transverse permeability values were determined for a very few fabrics only. The knowledge of an exact transverse permeability is important for the three-dimensional simulation of flow through thick sectioned parts and for specific RTM-related processes like resin film infusion or SCRIMP(R). This paper addresses the monitoring of flow front propagation utilizing ultrasound transmission. A testing rig was developed for monitoring three-dimensional ellipsoidal impregnation, which is induced by point injection. Two multidirectional non-crimped fabrics were characterised by the three-dimensional measurement. For the determination of the transverse permeability the three-dimensional filling was emulated by a numerical flow simulation software. (C) 2003 Elsevier Science Ltd. All rights reserved.