Determination of the Unsaturated Through-Thickness Permeability of Fibrous Preforms Based on Flow Front Detection by Ultrasound

摘要

The permeability of fibrous preforms used as reinforcements for fiber-reinforced polymeric composites is a decisive parameter for simulation-based predictions of common defects that occur during the filling process. This study focuses on the transverse permeability which becomes important for high thickness parts. An instrument that detects the transverse flow front by ultrasound and determines the transverse permeability has been developed. In contrast to other approaches, the developed permeameter uses a nondeflecting (metallic) tool while the selected sensing method is nonintrusive to the material. Novel electromechanical features allow a wide range of measurable preforms. The remaining limitations of the system have been identified and the model that correlates raw ultrasound measurements with flow front has been verified by visual observations. The transverse permeabilities of 18 different preforms have been determined in an experimental scheme designed to isolate the influence of preform thickness. (C) 2016 Society of Plastics Engineers