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Tervoort, Theo A.; Smit, Rjm Robert; Brekelmans, Wam Marcel; Govaert, Leon Le

doi:10.1023/a:1009720708029

Cited by 158 publications

(55 citation statements)

References 24 publications

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“…12 Govaert et al 5 extended the model by incorporating pressure dependence (µ) and intrinsic strain softening (D) in the viscosity function:…”

Section: Numerical Modelingmentioning

confidence: 99%

“…The Poisson ratio ν can be determined by monitoring the transverse strain in a uniaxial tension or compression test, for polycarbonate a value of 0.4 was found. 12 The most commonly encountered method to obtain the pressure dependence µ is by measuring the strain rate dependence of the yield stress in different loading geometries (e.g., uniaxial, or planar, tension and compression, shear, etc.). 28,38,39 The disadvantage of this method is that each geometry requires its own, optimized, sample shape and dimensions.…”

Section: Characterization Of Intrinsic Behaviormentioning

confidence: 99%

See 1 more Smart Citation

Modeling of the Postyield Response of Glassy Polymers: Influence of Thermomechanical History

Klompen¹,

Engels²,

Govaert³

et al. 2005

Macromolecules

223

386

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The continuous development of constitutive equations for the finite strain deformation of glassy polymers has resulted in a number of sophisticated models that can accurately capture the materials' intrinsic behavior. Numerical simulations using these models revealed that the thermal history plays a crucial role in the macroscopic deformation. Generally, macroscopic behavior is assumed not to change during a test, however, for certain test conditions this does not hold and a relevant change in mechanical properties, known as physical aging, can be observed. To investigate the consequences of this change in material structure, the existing models are modified and enhanced by incorporating an aging term, and its parameters are determined. The result is a validated constitutive relation that is able to describe the deformation behavior of, in our case, polycarbonate over a large range of molecular weights and thermal histories, with one parameter set only.

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“…12 Govaert et al 5 extended the model by incorporating pressure dependence (µ) and intrinsic strain softening (D) in the viscosity function:…”

Section: Numerical Modelingmentioning

confidence: 99%

Section: Characterization Of Intrinsic Behaviormentioning

confidence: 99%

Modeling of the Postyield Response of Glassy Polymers: Influence of Thermomechanical History

Klompen¹,

Engels²,

Govaert³

et al. 2005

Macromolecules

223

386

View full text Add to dashboard Cite

show abstract

“…This plastic flow process is represented by a nonlinear Maxwell model 40 as suggested by Baaijens. 41 Under isothermal conditions the nonlinearity of the model is completely governed by a stress, pressure, and state dependent viscosity η, which is defined as Here the part marked I, where τ j is the equivalent stress, represents the stress dependence of the viscosity governed by the parameter τ 0 .…”

Section: Constitutive Modelingmentioning

confidence: 99%

Quantitative Prediction of Long-Term Failure of Polycarbonate

et al. 2005

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Time-to-failure of polymers, and the actual failure mode, are influenced by stress, temperature, processing history, and molecular weight. We show that long-term ductile failure under constant load is governed by the same process as short term ductile failure at constant rate of deformation. Failure proves to originate from the polymer's intrinsic deformation behavior, more particularly the true strain softening after yield, which inherently leads to the initiation of localized deformation zones. In a previous study, we developed a constitutive model that includes physical aging and is capable of numerically predicting plastic instabilities. Using this model the ductile failure of polycarbonates with different thermal histories, subjected to constant loads, is accurately predicted also for different loading geometries. Even the endurance limit, observed for quenched materials, is predicted and it is shown that it originates from the structural evolution due to physical aging that occurs during loading. For low molecular weight materials this same process causes a ductile-to-brittle transition. A quantitative prediction thereof is, however, outside the scope of this paper and requires a more detailed study.

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“…In previous work we developed an 3D elasto-viscoplastic constitutive equation that accurately captures the deformation characteristics of polymer glasses [15,16,20,21]. The basis of this constitutive model is the division of the total stress into two contributions, first proposed by Howard and Thackray [22]:…”

Section: Constitutive Modellingmentioning

confidence: 99%

“…The so-called driving stress s in equation (4) accounts for the rate-dependent plastic flow response, attributed to intermolecular interactions on a segmental scale [15,21] and is represented by a compressible Leonov model [20,24]:…”

Section: Constitutive Modellingmentioning

confidence: 99%