Numerical simulation of injection/compression liquid composite molding. Part 2: Preform compression

K. M. Pillai, C. L. Tucker, F. R. Phelan

Research output: Contribution to journalArticlepeer-review

Abstract

In the injection/compression liquid composite molding process (I/C-LCM), a liquid polymer resin is injected into a partially open mold, which contains a preform of reinforcing fibers. After some or all of the resin has been injected, the mold is closed, compressing the preform and causing additional resin flow. This paper addresses compression of the preform, with particular emphasis on modeling three-dimensional mold geometries and multi-layer preforms in which the layers have different mechanical responses. First, a new constitutive relation is developed to model the mechanical response of fiber mats during compression. We introduce a new form of nonlinear elasticity for transversely isotropic materials. A special case of this form is chosen that includes the compressive stress generated by changes in mat thickness, but suppresses all other responses. This avoids the need to model slip of the preform along the mold surface. Second, a finite element method, based on the principle of virtual displacement, is developed to solve for the deformation of the preform at any stage of mold closing. The formulation includes both geometric and material nonlinearities, and uses a full Newton-Raphson iteration in the solution. An open gap above the preform can be incorporated by treating the gap as a distinct material layer with a very small stiffness. Examples show that this approach successfully predicts compression in dry preforms for three-dimensional I/C-LCM molds.

Original languageEnglish (US)
Pages (from-to)207-220
Number of pages14
JournalComposites Part A: Applied Science and Manufacturing
Volume32
Issue number2
DOIs
StatePublished - Feb 2001

ASJC Scopus subject areas

  • Ceramics and Composites
  • Mechanics of Materials

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