Creep rupture of polymers-a statistical model

Vujosevic, Milena; Krajčinović, Dušan

doi:10.1016/s0020-7683(96)00067-4

Cited by 34 publications

(21 citation statements)

References 25 publications

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“…This algorithm more faithfully reproduces fiber-breaking processes than the standard algorithm used for triangular lattice models (e.g., Refs. [23,26,27,32]). It should be noted that the random number generation [following exponential distribution in Eq.…”

Section: B Stochastic Fiber Lifetime Modelmentioning

confidence: 99%

“…This model has been used in the past by many researchers to investigate various aspects of statistical failure under both static strength and creep test conditions (for example, Refs. [26,27]). In this paper we use this network structure specifically to examine the size scaling, the shapes of lifetime distributions, and the damage evolution law.…”

Section: Introductionmentioning

confidence: 99%

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Time-dependent statistical failure of fiber networks

Mattsson

Uesaka

2015

Phys. Rev. E

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Numerical simulations of time-dependent stochastic failure of fiber network have been performed by using a central-force, triangular lattice model. This two-dimensional (2D) network can be seen as the next level of structural hierarchy to fiber bundles, which have been investigated for many years both theoretically and numerically. Unlike fiber bundle models, the load sharing of the fiber network is determined by the network mechanics rather than a preassigned rule, and its failure is defined as the point of avalanche rather than the total fiber failure. We have assumed that the fiber in the network follows Coleman's probabilistic failure law [B. D. Coleman, J. Appl. Phys. 29, 968 (1958)] with the Weibull shape parameter β = 1 (memory less fiber). Our interests are how the fiber-level probabilistic failure law is transformed into the one for the network and how the failure characteristics and disorders on the fiber level influence the network failure response. The simulation results showed that, with increasing the size of the network (N ), weakest-link scaling (WLS) appeared and each lifetime distribution at a given size approximately followed Weibull distribution. However, the scaling behavior of the mean and the Weibull shape parameter clearly deviate from what we can predict from the WLS of Weibull distribution. We have found that a characteristic distribution function has, in fact, a double exponential form, not Weibull form. Accordingly, for the 2D network system, Coleman's probabilistic failure law holds but only approximately. Comparing the fiber and network failure properties, we found that the network structure induces an increase of the load sensitivity factor ρ (more brittle than fiber) and Weibull shape parameter β (less uncertainty of lifetime). Superimposed disorders on the fiber level reduce all these properties for the network.

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Section: B Stochastic Fiber Lifetime Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Time-dependent statistical failure of fiber networks

Mattsson

Uesaka

2015

Phys. Rev. E

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“…Taking into account that the statistical properties related to failure such as stress-, strain-, and timeto-failure have got a kind of minimum nature therefore they can be described with the Weibull distribution that is the extreme value distribution of minima [22] under sufficiently general conditions in both practice and theory [23] shown by e.g. Phoenix [24,25], Wagner et al [16], or later Raghavan and Meshii [17], Vujosevic and Krajcinovic [18], or recently Fancey [26]. Hence it can be applied to the distribution of both the strength, " B0 , and the transformed lifetime, ', as well (Equation (11)).…”

Section: Measurementsmentioning

confidence: 99%

“…In some cases constitutive mechanical models are developed using measured material constants and numerical analysis [13] or finite element models are created to describe thermoelastic creep [14]. In opposite to them models based on the kinetic, thermal activation, or micro-deformation behavior of molecule chains are developed to predict the creep of polymers [15][16][17][18]. In general these methods can be used just at or below a given load level and in most cases they can-not estimate the expected lifetime and/or the creep strain-to-failure.…”

Section: Introductionmentioning

confidence: 99%

Estimating the creep strain to failure of PP at different load levels based on short term tests and Weibull characterization

Vas¹,

Bakonyi²

2012

Express Polym. Lett.

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Abstract. The short and long term creep behavior is one of the most important properties of polymers used for engineering applications. In order to study this kind of behavior of PP tensile and short term creep measurements were performed and analyzed using long term creep behavior estimating method based on short term tensile and creep tests performed at room temperature, viscoelastic behavior, and variable transformations. Applying Weibull distribution based approximations for the measured curves predictions for the creep strain to failure depending on the creep load were determined and the parameters were found by fitting the measurements. The upper, mean, and lower estimations as well as the confidence interval for the means give a possibility for designers' calculations at arbitrary creep load levels.

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“…The experiments verified the theoretical predictions for the strength but were not very conclusive for the creep rupture, pointing the need for more reliable characterization of the fibre strength, matrix creep and the time-dependent debonding at the fibre matrix interface. More recently Vujosevic et al [31] developed a micromechanical statistical model to predict the creep and creep rupture of epoxy resins, using a 2D lattice to describe the microstructure and a probabilistic kinetic theory of rupture of the molecular chains to characterize the creep deformation evolution. The time to creep failure is defined as the state at which the lattice stiffness reaches a zero value.…”

Section: Introductionmentioning

confidence: 99%

Time-dependent failure criteria for lifetime prediction of polymer matrix composite structures

Guedes

2011

Creep and Fatigue in Polymer Matrix Composites

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The use of fibre -reinforced polymers in civil construction applications originated structures with a high specific stiffness and strength. Although these structures usually present a high mechanical performance, their strength and stiffness may decay significantly over time. This is mainly due to the viscoelastic nature of the matrix, damage accumulation and propagation within the matrix and fibre breaking. One serious consequence, as a result of static fatigue (creep failure), is a premature failure which is usually catastrophic. However in civil engineering applications, the structural components are supposed to remain in service for 50 years or more in safety conditions.One argument used to replace steel by polymer-matrix composites is its superior corrosion resistance. Yet stress corrosion of glass fibre s takes place as soon as moisture reaches the fibre by absorption. This phenomenon accelerates fibre breaking. In most 2 civil engineering applications, glass-fibre reinforced polymers (GRP) are the most common especially because raw material is less expensive.The lack of full understanding of the fundamental parameters controlling long-term materials performance necessarily leads to over-design and, furthermore, inhibits greater utilization. In this context, lifetime prediction of these structures is an important issue to be solved before wider dissemination of civil engineering applications can take place. As an example, standards dealing with certification of GRP pipes require at least 10000 hours of testing for a high number of specimens. Even though these strong requirements may be foreseen as reasonable, concerning the safety of civil engineering applications, they severely restrict the improvement and innovation of new products.The present chapter reviews some theoretical approaches for long-term criteria. Timedependent failure criteria will be presented and developed for practical applications and illustrated with experimental cases.

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Creep rupture of polymers-a statistical model

Cited by 34 publications

References 25 publications

Time-dependent statistical failure of fiber networks

Time-dependent statistical failure of fiber networks

Estimating the creep strain to failure of PP at different load levels based on short term tests and Weibull characterization

Time-dependent failure criteria for lifetime prediction of polymer matrix composite structures

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