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

International audienceThe 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 post-filling 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

Simulation of the reinforcement compaction and resin flow during the complete resin infusion process

International audienceResin infusion (a.k.a. VARTM) is one of the LCM processes, for which liquid resin is drawn into dry reinforcements. Significant cavity thickness changes occur during processing, due to the flexibility of the vacuum bag used as one side of the tool, and the complex stress balance within the laminate. While the magnitude of thickness change is often small, the influence is significant on reinforcement properties. Changes in permeability during filling and post-filling have the potential to significantly affect the process. To simulate this behaviour, it is important to accurately model compaction and unloading of reinforcement in dry and wet states. A series of tests were completed to determine compaction behaviour of an isotropic glass fibre mat. From these tests several non-linear elastic compaction models have been determined, and applied within a resin infusion simulation which addresses pre-filling, filling and post-filling. This simulation was then used to assess different post-filling strategies

Full field monitoring of the resin flow and laminate properties during the resin infusion process

International audienceThe resin infusion process (a.k.a. VARTM, SCRIMP) has developed as a low cost method for manufacturing large fibre reinforced plastic parts. This process still presents some challenges to industry with regards to reliability and repeatability, resulting in trial and error development being expensive and inefficient. This paper describes a fully instrumented resin infusion setup, providing preliminary experimental data acquired while varying influential parameters during the filling and post-filling stages. The laminate per-meability is a strong function of the fibre volume fraction which can be determined from the laminate thickness. To assess the variation of the volume fraction and permeability, full field thickness variations have been monitored using a digital speckle stereophotogrammetry system developed for this purpose. In-mould resin pressures, flow front progression, and incoming resin flow rate were also measured. A selection of four experiments is presented here for discussion

2.0 rCF based composite materials: manufacturing processes and mechanical properties

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Processability of Biobased Thermoset Resins and Flax Fibres Reinforcements Using Vacuum Assisted Resin Transfer Moulding

International audienceBiocomposite panels consisting of biobased thermoset resins (EP, PU, UP, and tannin) and flax fibre reinforcements were produced using the vacuum assisted resin transfer moulding process. Panels based on a conventional chemical-based resin matrix were also produced, and investigated comparatively. Rheometric analyses were performed to evaluate the suitability of these resins for liquid composite moulding. Tensile, shear, and impact-bending tests have been carried out to assess the quality and mechanical performance of manufactured laminates. The impregnation quality was assessed by means of ultrasonic-C-scanning and microscopy. It turned out that the properties of the biobased composite panels made of biobased epoxy resin and a biobased UP-resin from the company Nuplex in New Zealand were onlay slightly inferior to those produced with a conventional epoxy resin. A biobased PU-resin from the company USSC in the USA developed voids during curing. A tannin-based resin containing of formaldehyde was not processable

OBSERVATIONS OF STRESS AND LAMINATE THICKNESS VARIATIONS IN LCM PROCESSES

International audienceClosed moulding processes are increasingly being used for the manufacture of fibre reinforced thermosets. A variety of mould construction methods and filling techniques are used, producing an ever expanding list of processes within the Liquid Composite Moulding (LCM) family. The long term goal of this research programme is the development of a generic LCM filling simulation, able to address processes utilising rigid, semi-rigid, and flexible moulds. This paper highlights recent developments in the experimental verification programme. A Tekscan dynamic pressure measurement system has been used to measure normal stresses exerted on a rigid mould during RTM and ICM cycles. A stereophotogrammetry technique has been employed to measure full field laminate thickness variations during Resin Infusion. Discussion is provided on initial results obtained with these systems

Control of laminate quality for parts manufactured using the resin infusion process

International audienceResin Infusion is a manufacturing process used to produce fibre reinforced thermo-set polymer components. This process is utilized in a range of industries such as aerospace, automotive, marine, rail and defense and is a cheaper method when compared to other closed mould or autoclave manufacturing methods, particularly as the size of the parts increases. In this study, wet compaction characteristics and behaviour of three glass fibre reinforcements were analyzed, and 2D panels were manufactured with a selection of inlet and vent pressure combinations during both the filling and post-filling stages of the process to achieve control of the final fibre volume fractions. Reinforcement thickness and resin pressure were monitored throughout each experiment and the achieved fibre volume fractions were measured post-manufacture. Void content was analyzed microscopically and related to the respective experimental parameters set. The compaction result fairly predicted the achieved fibre volume fraction of the manufactured part. The possibility of controlling the fibre volume fraction through control of the post-filling pressure was demonstrated. Even though there was a risk of increased void content with some post-filling configurations, the fibre volume fraction could still be controlled without creating voids with careful application of post-filling conditions. ABSTRACT Resin Infusion is a manufacturing process used to produce fibre reinforced thermo-set polyme

Resin infusion/liquid composite moulding (LCM) of advanced fibre-reinforced polymer (FRP)

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HOMOGENISATION OF COMPACTION BEHAVIOUR AND PERMEABILITY FOR MULTI-LAYERED COMPOSITE STRUCTURES MANUFACTURED VIA LCM PROCESSES

International audienceModern composite structures make use of the possibilities offered by composite materials to add stiffness and strength only where they are needed and in the direction required. This ability to tailor material properties to the needs of the structure have led to significant weight reductions; they have also allowed one to develop new architectures and design shapes, as composites materials are usually formed at the same time as the part they form. The Liquid Composite Moulding (LCM) family of processes, comprising RTM, CRTM, RTMLight and Resin Infusion VARTM, involves the placement of dry fibrous reinforcement into a mould and then, after closing the mould, injection of liquid resin to impregnate the reinforcement before resin-cure. LCM processes have a number of advantages over other processes; these include control over harmful volatiles, the ability to achieve high and consistent final fibre volume fraction (V f) and their potential for automation, greatly reducing labour costs [1, 2]. During manufacture with an LCM process, the operator typically has little control. Successful process development by trial and error, on the other hand, requires experience and can be time consuming and expensive. Reduction of development costs requires a good understanding of the process physics, and can benefit from development of an accurate simulation tool. Significant effort has been placed into establishment of RTM and CRTM simulations that accurately predict process outcomes, such as fill time, flow front advancement and dry spot formation [3, 4]. SimLCM is a simulation software developed at the University of Auckland to simulate LCM processes. Incorporation of the compaction behaviour of the fibrous reinforcement into the simulation allows for calculation of the tooling forces. Modelling of the reinforcement compaction also allows one to calculate the changes in permeability which occur during compaction, which is necessary for providing accurate simulation of the CRTM process. To determine the compaction and permeability behaviour, a set of experimental characterisation is required. Experimental procedures for reinforcement characterisation were devised and presented in [5-8] and [8, 9], respectively, for the compaction and permeability. Using thes

Monitoring variations in laminate properties through the complete resin infusion process

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