INCORPORATING PROCESS AND MATERIAL VARIABILITY IN LIQUID COMPOSITE MANUFACTURING SIMULATIONS FOR SEAMLESS INTEGRATION IN COMPOSITE DESIGN

摘要

In Resin Transfer Molding (RTM) or Vacuum Assisted Resin Transfer Molding (VARTM) theprocess design requires an infusion and venting scheme which will saturate all the empty spacesbetween the fibers during mold filling resulting in a composite part without voids. However, theinherent process variability can change the filling patterns significantly which complicates thistask. The objective of this work is to develop manufacturing simulation tools that will examinethe designed part geometry and material layups for ease of manufacturing with feasible infusionschemes by accounting for the inherent variability of the material and preform layup during theinfusion process. To accomplish this, the integrated tool has to automatically identify possibleregions that are likely to introduce variability in resin flow, such as channels around edges of thepart or high fiber volume regions, which will cause dramatically different resin flow patterns andcould result in voids. These possible scenarios can then be simulated and evaluated beforeformulating an injection and venting scheme for the selected net shaped part.This paper presents the development of new tools to address this. It utilizes the well-tested LCMfilling simulation package known as Liquid Injection Molding Simulation (LIMS) and couples itwith newly developed software tools that analyze the design geometry and infusion layout, asrepresented by the shell mesh of the part, to determine possible flow disturbances. The range ofpossible processing scenarios, and their statistical probability, is generated automatically, and aset of simulations is executed to determine the effects of process variability due to the suggestedinfusion scheme. The resulting filling flow-patterns are compiled and analyzed to determinenecessary infusion timing and proper venting arrangement. The estimated success rate iscomputed and, problematic disturbances detected and recommendations are provided to thedesigner for possible design modifications.