Numerical and experimental analyses in composites processing: impregnation, heat transfer, resin cure and residual stresses

Filip Bo Salling,Jesper H Hattel,Michael Sandberg,Jon Spangenberg

doi:10.1088/1757-899x/942/1/012003

Abstract

This is a literature review of the published scientific results by the authors on numerical modelling and experimental characterization of composites processing with a focus on the resin injection pultrusion (RIP) process. Differential scanning calorimetry is used to obtain cure kinetic parameters for an epoxy resin system. The cure kinetic parameters are used for thermo-chemical simulations of the RIP process which are subsequently validated by temperature measurements. Scanning Electron Microscopy (SEM) and X-ray Computed Tomography (XCT) are used to characterize the microstructure of a glass fiber reinforced polyurethane profile. SEM was used to obtain the variation in cross-sectional fiber volume fraction and subsequently relating this variation to permeability. XCT was used to obtain individual fiber inclination and relating these inclinations to the observed reduction in longitudinal stiffness as proposed in literature by Herbert Krenchel. Considering multi-physics modelling of the RIP process two new state-of-the-art approaches are summarized in this work: i) a coupled flow-thermo-chemical model necessary for thick-section profiles, and ii) a steady state 3D-Eulerian approach for thermo-chemical-mechanical simulations showing a significant increase in computational performance compared with the traditional Lagrangian approach. Finally a study by Mortensen et al., on how to minimize residual stresses by minimizing the gelation temperature is reviewed.

Highlights

Composite materials, in the form of Fiber Reinforced Polymers (FRP), have in recent years been increasingly used for various structural applications, e.g. in the construction, automotive, and wind energy sectors
The cure kinetic parameters are used for thermo-chemical simulations of the Resin Injection Pultrusion (RIP) process which are subsequently validated by temperature measurements
The first case will be used to evaluate the cure kinetic parameters obtained from Differential Scanning Calorimetry (DSC) by comparison of simulation results and in process temperature measurements; the second case will illustrate the importance of a coupled flow-thermochemical modelling approach considering RIP of thick-section profiles; and the third case will illustrate state-of-the-art thermo-chemical-mechanical simulations of the RIP process

Summary

Introduction

In the form of Fiber Reinforced Polymers (FRP), have in recent years been increasingly used for various structural applications, e.g. in the construction-, automotive-, and wind energy sectors. 2. Numerical Analyses in Composites Processing Manufacturing of high quality FRPs is directly related to the multi-physics involved during production, i.e. impregnation flow, heat transfer, chemical cure or polymerization, constitutive material behavior, and solid mechanics. In the case of a continuous composite manufacturing process, e.g. pultrusion, a velocity component in the pulling direction should be included and the advective nature of the pultrusion process should be accounted for when updating the degree of cure (thermosets) [18,22]. The latter can be expressed in the following way:.

Constitutive Material Modelling

Findings

Conclusion