Numerical technique for determination of transverse permeability in RTM composites
Fabiane Valente Harter1; Elizaldo Domingues dos Santos1; Liércio André Isoldi1; Jeferson Avila Souza1; Sandro Campos Amico2
1 Federal University of Rio Grande; 2 Federal University of Rio Grande do Sul
doi:10.20906/CPS/COB-2015-2012
Resumo
With increasing demand for composite materials in different areas of application, manufacturing techniques are constantly being developed and improved. Liquid Composite Molding (LCM) processes comprises a number of injection techniques largely use in aerospace, automotive and naval industries. RTM (Resin transfer molding) process is an example of LCM on which a fibrous reinforcement is compressed and placed into a mold cavity. Resin is than injected into this cavity mold through one or more injection points. With the RTM process it is possible to produce pieces with excellent control of its mechanical properties and with complex geometry. It is also possible to produce products with large dimensions with competitive low production costs. This advantages are only achieved when process parameters such as media permeability and porosity, resin viscosity and density and injection pressure are known and controlled. Among these important control parameters, determination of transverse permeability in 3D geometry pieces is an important properties which is relatively difficult to be determined. There are a large number of consolidated techniques for in-plane permeability determination, however transverse permeability determination stills being a challenger in many cases. Motivated by the above discussion, this word focus on developing a numerical methodology for the determination of transverse permeability of reinforced medias used in RTM process. The method consists in using an inverse problem of estimating parameters to calculated the unknown transverse permeability. Inlet pressure and flow position as a function of time are measured experimentally and the mathematical model is solved for the permeability. Newton-Raphson method is combined with a CFD solution (obtained with PAM-RTM software) to solve the problem. Results showed that permeability can be precisely calculated with data measured in the final geometry model, i.e., it is not necessary to build and specific mold for the permeability experiment determination.
Palavras-chave: transverse permeability; RTM; numerical modeling