Multi-scale modeling and online monitoring of resin flow through dual-scale textiles in liquid composite molding processes

Flow enhancement in liquid composite molding processes by online microwave resin preheating

“…The mold was instrumented with three dielectric sensors placed at fixed distances from the inlet point along the main flow direction, hereinafter called sensors S1, S2, and S3, respectively [48][49][50][51][52][53] (see in Figure 1). Two transparent eyelets were drilled on the upper mold for visual inspection of the flow advancement independently from the measurements by employing the sensors.…”

“…Eyelet and dielectric sensors enable to continuously monitor the advancement of the resin during the impregnation. The scheme and working principles of sensors utilized can be found elsewhere [49,50] and were omitted here for the sake of brevity. The level sensor, placed on the resin reservoir, was used for the resin flow rate evaluation during the infusion.…”

“…The paper first reports the results of preliminary tests on the microwave system, investigating the correlation between resin flow rate, microwave power, and cavity length. Dielectric analysis methodology [49][50][51] has been adopted to closely monitor the resin infusion in a purely 1D flow test and evaluate the benefits deriving from the implementation of the microwave heating system in terms of impregnation time.…”

Modelling the permeability of random discontinuous carbon fibre preforms

“…In general, the permeability of dual-scale reinforcements, such as fabrics, where continuous fibre bundles are arranged in a defined pattern, or DCFP materials, where discontinuous fibre bundles are arranged randomly, is governed by flow in the fibre bundles and between the bundles. This dual-scale permeability has been studied numerically and experimentally for saturated and unsaturated flow in liquid moulding processes [6][7][8][9]. To account for the difference in flow velocities in bundles and between bundles, which typically results in delayed impregnation of the fibre bundles in unsaturated flow, it has been proposed to model fibre bundles as a fluid sink in a porous medium with uniform permeability [8,9].…”

“…This dual-scale permeability has been studied numerically and experimentally for saturated and unsaturated flow in liquid moulding processes [6][7][8][9]. To account for the difference in flow velocities in bundles and between bundles, which typically results in delayed impregnation of the fibre bundles in unsaturated flow, it has been proposed to model fibre bundles as a fluid sink in a porous medium with uniform permeability [8,9]. Furthermore, unsaturated flow is affected by capillary pressure which is sometimes considered in modelling of flow and void formation within fibre bundles [8,[10][11][12].…”