Viscoelastic Analysis of Processing-Induced Residual Stresses in Thick Composite Laminates

Kim, Yeong K.; White, Scott R.

doi:10.1080/10759419708945889

Cited by 86 publications

(42 citation statements)

References 16 publications

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“…-implementing the modelling of the development of process-induced stresses [6][7][8][9][10][11][12][13][14][15][16][17][18][19]; -implementing the computation of process-induced stresses [20][21][22][23][24][25][26][27][28]; -measuring process-induced strains [29][30][31][32][33][34][35][36][37][38][39][40][41] -integrating in the computation of process-induced stresses, the interactions between the manufactured composite part and tooling [28,[42][43][44][45][46][47][48][49].…”

Section: Process-induced Stresses: a Brief Overview Of Backgroundmentioning

confidence: 99%

Designing curing conditions in order to analyse the influence of process-induced stresses upon some mechanical properties of carbon / epoxy laminates at constant Tg and degree of cure

Olivier

Sawi

2010

Int J Mater Form

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In the aim to study of the effects of processinduced stresses upon some mechanical properties of simple stacking sequence composite laminates, three different cure cycles were designed. This was achieved on the basis of a cure kinetics modelling. A minimum number of curing parameters were modified in order to restrain changes in material physical properties. Those latter were determined from the molecular network of the thermosetting matrix to the fibres volume fraction and thermal expansion of the laminated plates. The level of processinduced stresses generated by the three cure cycles was assessed by measuring the out-of-plane deflection on unsymmetrical laminated strips. Manufactured laminates were submitted to a set of tensile tests in order to determine the changes in their mechanical properties due to the different curing conditions. All the mechanical tests were followed by acoustic emission. This has enabled to distinguish the occurrence of the various damaging processes with respect to curing conditions and therefore process-induced stresses. Lastly, process-induced stresses on a micromechanical level were theoretically determined. This determination has enabled a first analysis of the effects of process-induced stresses upon mechanical properties to be settled.

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Section: Process-induced Stresses: a Brief Overview Of Backgroundmentioning

confidence: 99%

Designing curing conditions in order to analyse the influence of process-induced stresses upon some mechanical properties of carbon / epoxy laminates at constant Tg and degree of cure

Olivier

Sawi

2010

Int J Mater Form

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“…The relevant properties of this composite, including the mechanical properties and reaction kinetics were systematically measured and reported by Kim and White [3,22,23].…”

Section: Development Of Viscoelasticity For Hercules As4/3501-6 Compomentioning

confidence: 99%

Residual stresses created during curing of a polymer matrix composite using a viscoelastic model

Zhang

et al. 2016

Composites Science and Technology

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. limited ranges of the Deborah number. By considering the evolution of the Deborah number during curing of the AS4/3501-6 composite, the composite is in a fully relaxed state when it is cured at high temperature and the degree of cure is lower than 0.73, and no further changes in the viscoelastic characteristics when the degree of cure is higher than 0.8. A 3D simulation of a composite laminate plate is used to predict the evolution of the residual stresses. The analysis reveals that the accurate simulation on the cure-induced residual stress should include the last two states of the entire cure process, and consider the stress relaxation, thermal deformation and chemical shrinkage.

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“…Although the flat plate geometry with uniform thickness may not warrant a threedimensional analysis, this case was used to benchmark and verify the performance of the present method. property development across the laminate thickness [13].…”

Section: Numerical Examplesmentioning

confidence: 99%

“…Therefore, the viscoelastic behavior of the resin should not be neglected in an accurate process model. The model used to depict the viscoelastic behavior of the composite was based on the work by Kim and White, [2], [27], [13], and [26]. The general expression for the constitutive relationship for an anisotropic linear viscoelastic material is [2]:…”

Section: Viscoelastic Formulationmentioning

confidence: 99%

“…In the work of Kim and White [26] and [13], residual stresses in thick j graphite/epoxy laminates were studied using a viscoelastic analysis, where the time-dependent stiffnesses were modeled using a series of exponential functions "^ and based on cure dependent relaxation times. It was found that the residual ^ stress developed in thick section composites was significant especially in the transverse direction.…”

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confidence: 99%

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Multi-Physics Modeling and Simulation of Process-Induced Stresses in Polymer-Matrix Composites

Pochiraju¹

2002

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Tlie public reporting burden for this coltection of information is estimated to average 1 iiour per response, including the gathering and maintaining the data needed, and completing and reviewing the collection of infomiation. Send comments reg.. wmn^mon oT infomiation, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, .-^^pwaiions arid Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstandhi? any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid 0MB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS.REPORT DATE (DD-MM-YYYY) What Was Accomplished;A Galerkin finite element with an Jacobi Conjugate Gradient (JCG) iterative solver is used to solve the thermal equilibrium and chemical kinetics during the curing phase of RTM process. The mold temperature history and molding process parameters are translated into initial and boundary conditions of the simulation. The temperature and degree of cure fields and their gradients are obtained during the curing process. Two material constitutive models describing the thermoelastic and viscoelastic behavior of the material are considered. Effective composite mechanical properties were computed using the instantaneous resin and fiber properties in a self-consistent field micromechanics model. For the viscoelastic constitutive equation, the cure and temperature dependent stress relaxation modulus was approximated as a Prony series of a number of Maxwell elements. The composite constitutive behavior is then implemented into a general purpose finite element software to determine the evolution of the residual stress and deformations with temperature and degree-of-cure dependent material behavior. Several numerical simulations are performed to compare the results with other numerical and approximate solutions available in the literature. Thus, a comprehensive methodology for predicting process-induced stress and deformations in composite materials is formulated, implemented and validated. Why It Is Important;Processing history strongly contributes to the residual stress development leading to part warpage and shrinkage and potential reduction in the absolute strength of the composite. Several applications, including modeling the residual stress and deformation evolution during RTM processing, analysis and optimization otprocess cycles for reduced process induced stress, and a novel use in the prediction of long term performance of the composites, are anticipated from the developed methodology. Symmetry FaceThree dimensional geometry of a typical part considered for numerical The degree of cure profiles shown at analysis. maximum exotherm point during cure Residual deformations after demolding. The temperature and degree of cure fields obtained from the cure simulation are used to examine the residual stress and defo...

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Viscoelastic Analysis of Processing-Induced Residual Stresses in Thick Composite Laminates

Cited by 86 publications

References 16 publications

Designing curing conditions in order to analyse the influence of process-induced stresses upon some mechanical properties of carbon / epoxy laminates at constant Tg and degree of cure

Designing curing conditions in order to analyse the influence of process-induced stresses upon some mechanical properties of carbon / epoxy laminates at constant Tg and degree of cure

Residual stresses created during curing of a polymer matrix composite using a viscoelastic model

Multi-Physics Modeling and Simulation of Process-Induced Stresses in Polymer-Matrix Composites

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