Process Modeling of Composite Manufacturing

Licentiate thesis, 2013

The focus of this research thesis is toward developing a framework for holistic modeling of composites manufacturing of fiber reinforced structural composites. The processes that have been considered are Liquid Composite Molding (LCM) and Out Of Autoclave (OOA) processes, ranging from Liquid Resin Infusion (LRI) and Resin Transfer Molding (RTM) in LCM processes, to Vacuum Bag Only (VBO) and Evac prepregs in OOA processes. To develop this framework the theory of two phase porous media has been extensively used and developed. A finite element formulation and implementation of the two phase problem has been developed for compressible-incompressible constituents using Taylor-Hood element assuming hyper-elastic material response for the fiber bed. The issues that are considered during the simulations are analysis of process physics such as (1) modeling the highly deformable preform and the shape of the membrane due to the considered loading conditions, (2) the free surface problem when the flow front is moving with respect to a flow front velocity into the vacuum zone of the porous media, (3) the coupling effects between macro-scale preform processes and meso-scale ply processes, (4) development of an anisotropic permeability model, (5) coupling effects between the solid and fluid phases. The proposed formulation has been implemented and numerical results are provided for both cases of LCM and OOA processes. As a main result a coupled displacement-pressure, geometrically non-linear, finite element simulation tool is developed. Numerical examples of an infusion problem of a hat-beam, simulating both RTM and LRI, and also a relaxation-compression test of a planar fluid filled VBO preform, for LCM and OOA processes respectively, are considered.