Experimental analysis of the planar compaction and preforming of unidirectional flax reinforcements using a thin paper or flax mat as binder for the UD fibers

Abstract

Transverse compaction and geometric conformation of fiber reinforcements have a significant importance in the production of complex dry fiber preforms for the resin transfer molding (RTM) process. This work investigates for the first time the planar compaction and preforming of two reinforcements made from aligned flax yarns held together by a thin layer of short kraft pulp or flax fibers. Planar compaction tests have been carried out in order to evaluate the influence of temperature, pressure, humidity and number of layers of reinforcement on the creep percentage, thickness recovery and permanent deformation of reinforcements. Next, the effect of process parameters on the quality of a complex 3D preform was evaluated. It appears that temperature, pressure and humidity increase the permanent deformation while the number of layers acts inversely. In addition, hot and wet made preforms have better dimensional stability (dimensions and geometry) than preforms obtained under other conditions.