Characterization of textile permeability as a function of fiber volume content with a single unidirectional injection experiment

Textile permeability is a fundamental property to describe preform impregnation in Liquid Composite Molding (LCM) processes. It depends on textile architecture and fiber volume content (FVC). Conventional methods to measure in-plane permeability are based on radial or unidirectional injection experiments performed at fixed FVC. A complete characterization involves a series of tests and requires several material samples. This study presents a novel approach to characterize permeability as a function of FVC through a unique unidirectional injection experiment with a preform containing different FVC sections. The same experimental set-up as in conventional unidirectional unsaturated permeability measurements is used with a second pressure transducer embedded in the mold in addition to the one located at the inlet gate. A fast algorithm is developed to exploit the data from the two sensors and automatically derive the permeability distribution without any need of visual flow front observations. The methodology is validated with a random fiber mat and a woven fabric. Results show that accurate permeability characterization can be achieved for both kinds of textiles.