Experimental Investigation of the Effect of Fiber-mat Architecture on the Unsaturated Flow in Liquid Composite Molding

摘要

In liquid composite molding technologies such as RTM,this study of the inlet-pressure history for the constant flow-rate 1-D flow experiment reveals that the measured pressure profile,which droop downwards as in earlier studies on the unsaturated flow,is at a variance with the linear pressure profile predicted by the physics used for state-of-the-art LCM mold filling similations.The droop along with the error in the inlet-pressure predictions increase with an increase in the fiber-mat compression.The effect of fiber-mat architecture on the droop in the inlet-pressure profiles is studied and significant droops are observed for various stitched mats as compared to the woven mats.This study repudiates the long-held view that mere presence of cylindrical or elliptical tows in the woven or stitched fiber-mats automatically leads to the unsaturated flow characteristic of dual-scale porous media;rather the presence of continuous uninterrupted macrochannels along the flow direction for preferential channel-flow is found to be necessary for the appearance of a dropping inlet-pressure history characteristic of the unsaturated flow.