Resin pressure evolution during autoclave curing of epoxy matrix composites

Abstract

During autoclave processing of composites for high‐performance applications, it is mandatory to limit the porosities, which mainly depend on the hydrostatic pressure in the resin. This pressure, which is not constant during heating being affected either by resin flow either by elastic stress in the fiber stack, can be significantly different from the autoclave pressure. Modeling of resin flow and stress in the fiber stack is a key issue for prediction of the resin hydrostatic pressure, which can be related to void development. Also, the viscosity of the thermosetting matrix is a relevant parameter since it is not constant but evolves during curing going through a minimum and then increasing to an infinite value at gel point. In this work, a viscoelastic model is adopted to calculate the evolution of resin pressure during an autoclave cycle up to gelation, accounting for viscosity and degree of reaction changes. Therefore, the model includes a kinetic and rheological model whose input parameters have been experimentally determined by Differential Scanning Calorimetry and rheological analysis. The predicted resin pressure for three case studies associated to different composite and bleeder thicknesses and reinforcement materials have been discussed. POLYM. ENG. SCI., 57:631–637, 2017. © 2017 Society of Plastics Engineers

Inspection of Carbon Fibre Reinforced Polymers: 3D identification and quantification of components by X-ray CT

“…A reference panel made up by T700 twill prepreg epoxy resin/carbon fibres (2 × 2 twill 12 k T700S pre-impregnated epoxy carbon fibre as supplied by Torayca) [41], consisting of [(0°/90°) 6 ] S layers, was built in high-pressure autoclave; details about the processing conditions and procedure can be find in Ref. [42].…”

Description of the Resin Curing Process—Formulation and Optimization

“…Due to this fact, a proper selection of the RK model is an important practical issue. On the basis of the validation of the particular models to the experimental tests [27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57], the practical recommendations regarding the selection of the RK models for composite materials (Table 1) and fabrication processes of fiber composites (Table 2) are given.…”

“…The above-mentioned models have been successfully applied to the different composite materials and resin systems such as carbon-fiber reinforced polymer (CFRP) [38,39,40,41,42,43,44], glass-fiber reinforced polymer (GFRP) [45,46,47,48], epoxy resin systems [49,50,51], fast cure epoxy [30,32,37]. The applicability of the curing models has been also confirmed for different manufacturing technologies of composite structures, such as: liquid silicone rubber (LSR) [52], resin film infusion (RFI) [53], resin transfer molding (RTM) [30,31,33,38,44,51,54], compression resin transfer molding (C-RTM) [32], reactive injection molding (RIM) [30], vacuum-assisted resin transfer molding (VARTM) [55,56], reactive extrusion (REX) [30], autoclaving [57] and out-of-autoclave (OOA) [34,37]. A detailed description is presented in Chapter 2.…”

Preparation and curing process optimization of an asymmetric impregnated vacuum bag-only prepreg

“…The application range of advanced resin-based composite materials in the aerospace field has gradually been applied from secondary load-bearing structures such as fairings and rudder surface structures to large-scale primary load-bearing structures such as aircraft wings and fuselage panels (Orifici et al, 2008). In addition, autoclave molding is the primary process for large composite structures (Abdelal et al, 2013;Lionetto et al, 2017). The composite components produced by autoclave molding include the advantages of high mechanical properties, low porosity, and good quality stability.…”