Manufacturing of laminar composites by RFI method
Mateusz Kozioł, Jerzy Myalski, Aleksandra Bogdan
Quarterly No. 3, 2009 pages 265-270
DOI:
keywords: laminar composite, RFI method, core-including composite, natural fibre composite
abstract The paper presents a task of manufacturing of exemplary composite structures using RFI method. Following preforms were manufactured on laboratory RFI device: glass-fibre reinforced laminate (10 layers of 350 g/m2, plain weave fabric), foam core - glass fibre mat laminate (facing: 2 layers of glass-fibre mat of 350 g/m2, core: PVC foam 10 mm thick, properly incissed into two perpendicular directions), flax unweave cloth (thick mat of 1050 g/m2). Polyester resin was applied as the composites’ matrix. Quality and mechanical properties of the manufactured composites were checked. It was claimed that RFI method gives very effective and fast impregnation of the preforms. The method is very suitable for impregnation of multilayer glass-fibre preforms. The RFI laminates have a fibre volume fraction and mechanical properties on higher level, when compared with equivalent hand lay-up laminates. RFI method fits also for manufacturing of foam core - glass-fibre mat laminates. Incissions and holes present in the core excellently improves the impregnation conditions, but at the same time, cause deterioration in mechanical properties of the laminate. The flax unweave cloth based composite soaks very well. However, it shows very low level of mechanical properties, and it demands to develop effective adhesion promotors, which would cause an increase in the properties. It is possible to apply the flax unweave-cloth composite as core material, replacing PVC or PUR foams. It has of about 100% higher mass dendity in comparison with the foam-core laminate, but at the same time, more than 200% higher flexural strength - it compensates the negative mass effect. To main problems of RFI technology belong amongst other: necessity of very precise sealing up the vacuum bag - mold frontier and good distribution of the resin along the preform, by means of properly placed ducts. Neglecting of these elements leads to unfavourable side effects. Very important is also arrangement of inlets and outlets in the mold. RFI method is very perspective technology and in near future, together with RTM technique, it will be the main way to manufacture composite products. It comes out of increasing requirements in term of safety and work-hygiene and the environmental protection (removing the harmful vapours from production-space) and increasing pressure on quality and repeatibillity of the products. The paper is a part of larger scientific programm aiming a determination of “boundary conditions” for introducing the RFI method into particular industrial applications.