Multiscale characterization and representation of composite materials during processing

Abstract

Given the importance of residual stresses and dimensional changes in composites manufacturing, process simulation has been the focus of many studies in recent years. Consequently, various constitutive models and simulation approaches have been developed and implemented for composites process simulation. In this paper, various constitutive models, ranging from elastic to nonlinear viscoelastic; and simulation approaches ranging from separated flow/solid phases to multiscale integrated phases are presented and their applicability for process simulation is discussed. Attention has been paid to practical aspects of the problem where the complexity of the model coupled with the complexity and size scaling of the structure increases the characterization and simulation costs. Two specific approaches and their application are presented in detail: the pseudo-viscoelastic cure hardening instantaneously linear elastic (CHILE) and linear viscoelastic (VE). It is shown that CHILE can predict the residual stress formation in simple cure cycles such as the one-hold cycle for HEXCEL AS4/8552 where the material does not devitrify during processing. It is also shown that using this simple approach, the cure cycle can be modified to lower the residual stress level and therefore increase the mechanical performance of the composite laminate. For a more complex cure cycle where the material is devitrified during a post-cure, it is shown that a more complex model such as VE is required. This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'.

Consolidation-Driven Defect Generation in Thick Composite Parts

“…Over the years, composite process simulations have helped the industry to save large amounts of money by reducing the number of manufacturing trials. Simulation tools for forming [4][5][6][7][8][9], resin flow/ infusion [10][11][12][13][14][15][16][17], or cure simulation and residual stress prediction [18][19][20][21][22] are now an integrated part of the toolbox available to the composite designers. These, used together, allow accurate prediction for the occurrence of a large range of defect types.…”

Visco-thermo-elastic Simulation Approach For Prediction of Cure-induced Residual Stresses in Fiber Reinforced Composites

“…Previously published work on cure-dependent resin behavior mainly focused on better understanding of conventional prepreg and RTM manufacturing processes [1][2][3][4]. Only few attempts were made to analyze the process-dependent properties of fast curing resins [5,6].…”

Measurement and prediction of residual strains and stresses during the cooling of a glass fibre reinforced PA66 matrix composite

“…The thermoplastic composites mechanical behavior during cooling has been treated thanks to several approaches in the literature. Different constitutive laws were investigated, and a recent study proposed to compare them [11]. Among them, the linear thermo-elastic approach can be found in many references [12][13][14][15].…”