Possibilities of predicting the creep of a polymeric fiber-reinforced plastic from the properties of the components

Sokolov, E. A.; Maksimov, R. D.

doi:10.1007/bf00860093

Cited by 5 publications

(13 citation statements)

References 3 publications

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“…The initial creep curves are borrowed from [4] for the CBM aramide fibers, from [7] for the polyamide-like fibers, and from [14] for the FM 10001 and FM 3001 nylon fibers.…”

Section: Linearity Established From Compliance Curvesmentioning

confidence: 99%

“…In the case of viscoelastic composites, the deformation properties of their components are determined from creep curves [4,7].…”

Section: Introductionmentioning

confidence: 99%

“…To determine the deformation and strength characteristics of composite materials from the properties of their components, it is necessary to determine these properties experimentally and define them analytically [10,13]. In the case of viscoelastic composites, the deformation properties of their components are determined from creep curves [4,7].…”

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confidence: 99%

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Calculating the Linear Creep Strains of Viscoelastic Fibers under Tension

2005

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The linearity domain for the viscoelastic properties of high-molecular organic fibers is determined. The linearity criteria are coincidence of experimental compliance curves and linearity of isochronic creep curves. Statistical criteria are used to establish linearity. The influence function in the constitutive equation of linear viscoelasticity is an Abel-type power kernel. The calculated and experimental creep strains are in good agreement both at the initial stage of deformation and after long-term loading Introduction. To determine the deformation and strength characteristics of composite materials from the properties of their components, it is necessary to determine these properties experimentally and define them analytically [10,13]. In the case of viscoelastic composites, the deformation properties of their components are determined from creep curves [4,7].A great variety of constitutive equations have been proposed to describe the creep of viscoelastic materials. The theory of hereditary viscoelasticity has been used most widely. The concept of linear viscoelasticity is well developed and widely applied. However, the parameters of constitutive equations are determined by approximating experimental creep curves plotted for several levels of stresses and averaging the resulting values. This necessitates extensive long-term creep tests and lead to significant errors in creep strains calculated using average coefficients. The issues remaining to be resolved are determining the linearity domain of viscoelastic properties and selecting a heredity kernel.A generalized rheological model based on the hypothesis of a unified isochronic deformation curve has been developed in [1]. The model allows us to predict the nature of creep (whether linear or nonlinear) and includes an easily implementable procedure of identifying the material constants. In the present paper, we use the model from [1] to calculate the linear creep strains of organic fibers used as reinforcement in organofibrous and hybrid composites. We will determine the domain of linear viscoelastic deformation of organic fibers and justify the structure of the heredity kernel that describes the features of creep of the fibers over the whole time interval.1. Problem Formulation. Subject of Research. The deformation properties of a linear viscoelastic medium under uniaxial tension may be described within the framework of small-deformation theory by the following constitutive equations of the Boltzmann-Volterra hereditary theory of viscoelasticity [9]:

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“…The initial creep curves are borrowed from [4] for the CBM aramide fibers, from [7] for the polyamide-like fibers, and from [14] for the FM 10001 and FM 3001 nylon fibers.…”

Section: Linearity Established From Compliance Curvesmentioning

confidence: 99%

“…In the case of viscoelastic composites, the deformation properties of their components are determined from creep curves [4,7].…”

Section: Introductionmentioning

confidence: 99%

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Calculating the Linear Creep Strains of Viscoelastic Fibers under Tension

2005

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“…Some of the results from such studies are reviewed in [8,9,14,15,23,30]. It should be noted that the overwhelming majority of studies deal with the linear range of long-term viscoelastic deformation.…”

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confidence: 98%

“…All solutions found are based on the Boltzmann-Volterra theory of linear viscoelasticity [11,31]. When used to predict creep strains of composites from the properties of their components, the linear theory is usually supplemented with the mixing rule [8,14,15,23].Theoretical and experimental studies of creep of various polymer composites show that the linear theory of viscoelasticity can be directly applied to a certain class of problems. In the majority of composites, however, the range of linearity is relatively short, and satisfactory results can only be obtained with not too high stresses and short-term loads.…”

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confidence: 99%

Nonlinear creep of unidirectional fibrous composites tensioned along the reinforcement

2007

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Creep strains in unidirectional organic-fiber-and organic-glass-fiber-reinforced plastics subject to tension in the reinforcement direction are predicted. Based on homogeneity condition and statistical criteria, it is shown that the creep of the composites is essentially nonlinear. To predict creep strains, use is made of a nonlinear creep model based on a modified Rabotnov's similarity hypothesis for isochrones and of material constants determined from tests on specimens made of a composite as a whole and specimens made of its separate components, the mixing rule applied in the latter case. The calculated results and the experimental data are in satisfactory agreement Introduction. Many unidirectional fibrous composites are engineering materials in which a viscoelastic matrix is reinforced with various organic and inorganic fibers. These composites are widely used in aeronautical and space engineering, shipbuilding, oil refinary, and oil and gas pipelines [1,8,14,21,23]. Fibrous composites as reinforcement of concrete structures have recently aroused considerable interest [26,32].Under long-term loads, viscoelastic fibrous composites creep even at temperatures far below the glass-transition temperature. This effect necessitates using creep strain, creep rate, relaxation time, creep limits, and long-term strength as the main deformation and strength characteristics of composites. One of the important problems in the mechanics of viscoelastic composites is to predict their viscoelastic properties from the properties and volume fractions of its components.A great many theoretical and experimental studies are concerned with various aspects of creep in unidirectional fibrous composites. Some of the results from such studies are reviewed in [8,9,14,15,23,30]. It should be noted that the overwhelming majority of studies deal with the linear range of long-term viscoelastic deformation. All solutions found are based on the Boltzmann-Volterra theory of linear viscoelasticity [11,31]. When used to predict creep strains of composites from the properties of their components, the linear theory is usually supplemented with the mixing rule [8,14,15,23].Theoretical and experimental studies of creep of various polymer composites show that the linear theory of viscoelasticity can be directly applied to a certain class of problems. In the majority of composites, however, the range of linearity is relatively short, and satisfactory results can only be obtained with not too high stresses and short-term loads. It should be taken into account that a portion of the creep strain may be irreversible.There are several approaches to describe the nonlinear viscoelastic deformation of composites. The general nonlinear equation of viscoelasticity was derived in [33]. It is represented by an infinite series of multiple integrals; therefore, it is not practical to identify numerous kernels and to determine their parameters experimentally. Similar difficulties arise in using the nonlinear models proposed in [4,6,7,10,13,22].The approach based on ...

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