Infusion Modeling Using Two Phase Porous Media Theory

Abstract

There are numerous ways to manufacture fibre reinforced polymer composites material ranging from hand lay-up in small series to fully automatic pressing of components to the automotive industry. One of the more advanced manufacturing processes of composites material is the Liquid Resin Infusion (LRI) of dry textiles. Examples of items made with this process are large scale composite structures used in aircrafts, hulls to sailing yachts and containers for transportation industry. What is desired for this arising technology is to numerically simulate manufacturing of high performance, integrated, large scale composite structures so that they can be designed and optimized efficiently. Common methods, like using layers of preimpregnated plies (prepregs) have some limitations such as, they are only usable for small scale components, have high material costs, limited formability, complex and expensive manufacturing and limited in shelf life. The LRI technology, in comparison to the common methods, has overcome these limitations and made this technology the preferred technology for large scale aerospace structures. The focus of this research project is to develop the simulation tools for modeling manufacturing process of a wide range of popular infusion technologies. To this end, the theory of two phase porous media with one solid and one fluid phase has been used along with assuming isotropic hyper-elastic material response for the fibre bed to formulate the problem. A finite element formulation and implementation of the two-phase problem has been developed for incompressible constituents using quadratic six-node elements. There are two major issues which will be considered in this project. The first one is to model the highly deformable preform and the shape of the membrane due to the considered pressure conditions. Compaction due to the atmospheric pressure is the main reason of the deformation of the preform which some of this deformation will be balanced off by the liquid pressure of the flowing resin. The second one is the free surface problem that the flow front is moving with respect to a flow front velocity into the vacuum zone of the porous media. Two approaches has been used to track the flow boundary, element saturation degree and the simplified level set method, which the result of the two are following the same behavior with some differences such as infusion time.