Experimental investigation into the post-filling stage of the resin infusion process

Abstract

The resin infusion process has developed as a low-cost method to produce large composite parts in low to medium quantities. Although the process is conceptually simple, the effects of many of the processing parameters on the postfilling stage of the process are not well understood. Most manufacturers tend to develop their approach to infusion process through trial and error, and then adhere to their 'secret recipe' without knowledge of the effect of each parameter. This paper describes an experimental investigation of the controllable process parameters and their effect on the final laminate composition, by monitoring local fluid pressure and full field laminate thickness data through the filling and post-filling stages. From the understanding of the effect of each parameter, guidelines are drawn to help manufacturers to optimise their process. The effect of using a 'brake' between the part and the vent are evaluated, and the benefits of turning the inlet into a vent at the onset of post-filling are highlighted together with methods of gaining some control on the final laminate fibre volume fraction.

Reduction of void content of vacuum‐assisted resin transfer molded composites by infusion pressure control

“…Consequently, the fiber volume content was only reduced by 0.8%. Govignon reported a similar result.…”

“…Another possible factor contributing to such a void content distribution was the evolution of the fluid pressure distribution. According to Govignon , after the resin saturates the entire stack, the fluid pressure shows a decreasing distribution along the resin flow direction. After the inlet is closed, the fluid pressure of the entire part, especially the part near the inlet, begins to decrease.…”

Dynamic pressure control in VARTM: Rapid fabrication of laminates with high fiber volume fraction and improved dimensional uniformity

“…Fabrication of laminates with uniform thickness is another challenging aspect of conventional VARTM due to nonuniform evolution of compaction pressure on the preform during filling . Although compaction pressure can be equalized after filling by bleeding the excess resin from the exit , bleeding of sufficient resin is usually time consuming and may not always be completed before gelation. Reducing the resin pressure below atmospheric level at the inlet to decrease the pressure gradient and achieve a more uniform laminate thickness was introduced as the controlled atmospheric pressure resin infusion (CAPRI) .…”

Monitoring the production of FRP composites: A review of in-line sensing methods

“…Validation experiments of various filling scenarios in a mould with a transparent top tool and 3 pressure sensors showed good agreement with visual data. Govignon et al [61] developed a monitoring system for Resin Infusion capable of capturing dynamically the fiber volume fraction via a stereophotogrammetry unit. Complementary distributed pressure sensors correlated the pressure gradient along the preform with thickness changes and provided additional data for comparison with simulations.…”