Viscoelastic behavior of an epoxy resin during cure below the glass transition temperature: Characterization and modeling

Courtois, Alice; Hirsekorn, Martin; Benavente, Maria; Jaillon, Agathe; Marcin, Lionel; Ruiz, Édu; Lévesque, Martin

doi:10.1177/0021998318781226

Cited by 53 publications

(55 citation statements)

References 36 publications

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“…Courtois et al [29] carried out relaxation tests on fully and partially cured specimens of the epoxy resin used in the studied composite at different temperatures below its glass transition temperature (T g ). Based upon their data, they proposed a 1D model for the tensile viscoelastic behavior of the resin as a function of temperature and degree of cure.…”

Section: Specification For the Polymer Matrixmentioning

confidence: 99%

“…To predict the homogenized behavior of the composite, we therefore need a full 3D model of the viscoelastic behavior of the matrix. If we use 1D model of Courtois et al [29] directly to model the evolution of the tensile modulus in a 3D model, this would imply the assumption of a constant Poisson ratio during relaxation. However, it was observed by Tschoegl et al [46], O'Brien et al [47] that the Poisson ratio increases during relaxation approaching values close to 0.5 for a fully relaxed material at high temperatures.…”

Section: Specification For the Polymer Matrixmentioning

confidence: 99%

“…In section 2, the formulation of the viscoelastic models used in this work is presented. A 3D generalization of the viscoelastic model developed by Courtois et al [29] for the polymer matrix of the studied composite is given in section 2.2. The proposed homogenization strategy is described in section 3 and validated numerically at the microscopic scale by comparison to full-field Finite Element (FE) calculations.…”

Section: Introductionmentioning

confidence: 99%

“…In all these works, the time-temperature superposition principle used, as it was shown to describe well the temperature dependence of the viscoelastic behavior of polymers [14,15,16,28]. The influence of the degree of cure was introduced in some works as an explicit dependence of the relaxation times on degree of cure [14,16,27], but it can also be modeled through a cure dependent T g used as reference temperature in the time-temperature superposition principle [15,25,28,29].In the present study we focus on composites with 3D woven reinforcements [30,31,32]. This type of composites became an interesting option for industrial applications since the development of modern looms capable of weaving complex reinforcement structures [30,31].…”

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Multi-scale modeling of the viscoelastic behavior of 3D woven composites

Hirsekorn

Marcin

Godon

2018

Composites Part A: Applied Science and Manufacturing

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A method is presented to predict numerically the homogenized viscoelastic behavior of 3D woven composites using only its constituents' behavior. It is based on elastic homogenizations applied to the Laplace-Carson transform of the time-dependent viscoelastic behavior of the constituents. Two scale chages are necessary: from micro-to meso-scale to obtain the homogenized behavior of the consolidated yarns, and from mesoto macro-scale. The temperature and cure dependent viscoelastic behavior of the matrix is identified from experimental data, using the time-temperature superposition principle with the cure dependent glass transition temperature as reference temperature. The meso-scale representative unit cell of the composite is extracted from X-ray microtomography images. The homogenized viscoelastic behavior is used to calculate the evolution of the apparent moduli of the composite with temperature between −50 • C and 200 • C. The results are in good agreement with experimental data over the temperature range where the matrix behavior was properly identified.While the mechanical behavior of carbon or glass fibers is linear elastic in a good approximation and almost independent of temperature, at least below the glass transition temperature (T g ) of typical thermosetting polymers (usually not exceeding about 200 • C), the mechanical behavior of the polymer matrix depends strongly on temperature and on the degree of cure [14,15,16,17,18,12]. Moreover, it is time dependent, i.e., creep and relaxation phenomena are observed, which may have a significant impact on the residual stresses and the final shape of composite parts [13,19,20,21]. As a consequence, residual stresses can be reduced by adapting the cure cycle such that relaxation phenomena are intensified [13,22].Since in the aeronautical industry highly precise part shapes are required, it is currently common practice to adapt the mold shape several times until the composite part fits the shape tolerances. This procedure of designing a composite part is very expensive, but can be greatly optimized if precise modeling tools are available that predict the generation of residual stresses and the final shape of composites with complex reinforcements, such as three-dimensional (3D) interlock weavings. To improve the accuracy of currently available modeling tools, it is necessary to take into account creep and relaxation and their dependence on temperature and degree of cure during the modeling of the curing and cooling process. The experimental characterization of a composite material required to determine the model parameters is complex and expensive, as 3D strain rate, temperature, and cure dependent mechanical behaviors have to be measured. Furthermore, these properties have to be re-identified, each time the reinforcement architecture is changed. Significant cost reduction is possible if only the constituent materials are fully characterized and the composite properties are predicted using multi-scale models.At small strains, creep, relaxation, and strain rate d...

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Section: Specification For the Polymer Matrixmentioning

confidence: 99%

Section: Specification For the Polymer Matrixmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Multi-scale modeling of the viscoelastic behavior of 3D woven composites

Hirsekorn

Marcin

Godon

2018

Composites Part A: Applied Science and Manufacturing

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Aspects of reproducibility and stability for partial cure of epoxy matrix resin

Müller

Winkler

Gude

et al. 2019

J of Applied Polymer Sci

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Partial cure of thermosets is a promising approach to enhance manufacturing possibilities of reinforced and unreinforced polymers. If partial cure is taken into consideration as a genuine process parameter, novel manufacturing technologies can be developed by exploiting the specific properties of incomplete polymer networks. A main concern in this context is to control the kinetic reaction avoiding inhomogeneous or instable degrees of cure. Based on a combination of numerical simulations and experiments, a methodology is presented that enables a systematic assessment of the reproducibility and stability of partial cure. Special attention is paid to the interaction of thermal boundary conditions and the cure kinetic of thick samples as well as the storability of partially cured resin under different conditions. Guidelines for cure cycle selection, mold design, and storage are derived. The possibility to use complex multistep cure schedules and extended storage periods is demonstrated for an unmodified noninhibited epoxy resin.

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A stacking sequence optimization strategy for process‐induced deformation of multi‐layer thick asymmetric laminates

Jia,

Zhu,

Yan

et al. 2024

Polymer Composites

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The occurrence of process‐induced deformations of composites laminates is challenging for assembly accuracy and may lead to a service life reduction of parts. However, it can be obviously mitigated through different optimization strategies on the basis of the accurate curing process simulation. In this study, a stacking sequence optimization strategy is proposed and applied to multi‐layer thick asymmetric laminates. The shapes of deformed laminate plates are experimentally investigated in virtue of the three‐dimensional coordinate measuring machine. The thermo‐chemical–mechanical behaviors of plates are first verified through the comparisons of model predicted and experimental process‐induced deformations. Then the nonlinear control formula achieved through the regression model is proposed for the direct relationship between stacking sequences and process‐induced deformations. Finally, the required solutions are generated by solving the control formula. With the comparisons between the average deformations before and after optimizations, it is found that the magnitudes of deformations are significantly reduced, especially when the unoptimizated deformations are large.Highlights The thermo‐chemical–mechanical behavior can be described in the curing process simulation model. The deformed shapes of multi‐layer thick asymmetric laminate plates are measured by a three‐dimensional coordinate measuring machine. The stacking sequence optimization strategy is implemented by introducing a nonlinear control formula.

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Viscoelastic behavior of an epoxy resin during cure below the glass transition temperature: Characterization and modeling

Cited by 53 publications

References 36 publications

Multi-scale modeling of the viscoelastic behavior of 3D woven composites

Multi-scale modeling of the viscoelastic behavior of 3D woven composites

Aspects of reproducibility and stability for partial cure of epoxy matrix resin

A stacking sequence optimization strategy for process‐induced deformation of multi‐layer thick asymmetric laminates

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