Lifetime predictions of polymer matrix composites under constant or monotonic load

Guedes, Rui Miranda

doi:10.1016/j.compositesa.2005.07.007

Cited by 50 publications

(42 citation statements)

References 41 publications

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“…As an approximation it is not difficult to conclude that we can take t~σ −2/n for the R-W and the MSW criteria and t~σ −1/n for the MS and the MR-W criteria. Similar results were obtained by using fracture mechanics concepts [39]. In fact these concepts established a relationship between time to failure, viscoelastic properties and strength properties [40]; [41], which are similar to the present approach.…”

Section: Energy-based Failure Criteriasupporting

confidence: 74%

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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Section: Energy-based Failure Criteriasupporting

confidence: 74%

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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“…Evaluation of lifetime of polymer structures is one of the key issues in their design as some areas of engineering demand lifetimes of 10-50 years (Guedes 2006;Orifici et al 2008). Creep-failure experiments serve as an effective method for assessment of long-term strength under time-independent loads.…”

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confidence: 99%

Creep failure of polypropylene: experiments and constitutive modeling

Drozdov

Christiansen

2009

Int J Fract

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Observations are reported on isotactic polypropylene in uniaxial tensile tests with various strain rates, relaxation tests with various strains, and creep tests with various stresses at ambient temperature. Constitutive equations are derived for the viscoelastic-viscoplastic responses and damage of a semicrystalline polymer at three-dimensional deformations. Adjustable parameters in the stress-strain relations are found by fitting the experimental data. The model is applied to predict creep-failure diagrams in the entire interval of stresses. A phenomenological approach is proposed to determine a knee stress, at which transition occurs from ductile to brittle rupture. Accuracy of this method is evaluated by numerical simulation.

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“…The life time of solids under tensile load has been investigated by experiments for a long time [2,3,5,7,8]. It was found, that Eq.…”

Section: Introductionmentioning

confidence: 98%

Life-time prediction for rocks under static compressive and tensile loads: a new simulation approach

2009

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The life time or time to failure of rocks under load is governed by microstructural defects, like microcracks, voids etc. The life time can be predicted either by empirical exponential laws or physical laws based on damage and fracture mechanics. The proposed numerical model is based on subcritical crack growth using the linear elastic fracture mechanical approach and is implemented as a numerical cellular automate. The algorithm considers both tensile and shear fracturing. Each cell contains a microcrack of random length according to a given probability function. Fracture growth is controlled by the Charles equation. Macroscopic cracks are the results of the coalescence of growing microcracks. Within the numerical approach elasto-plastic stress redistributions take place. If the stress intensity factors have reached the critical values or the microcrack has reached the zone dimension, the zone is considered as fractured and residual strength values are assigned. The proposed approach was applied to rock samples under uniaxial compressive and tensile loads (creep tests). Successful results were obtained in respect to the predicted life time, damage evolution and the fracture pattern. Conclusions for further improvements and extensions of this methodology were drawn.

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Lifetime predictions of polymer matrix composites under constant or monotonic load

Cited by 50 publications

References 41 publications

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

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

Creep failure of polypropylene: experiments and constitutive modeling

Life-time prediction for rocks under static compressive and tensile loads: a new simulation approach

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