Failure of unidirectional carbon-reinforced plastics and the realization of the strength properties of the fibers in these plastics

Tamuzh, V. P.; Azarova, M. T.; Bondarenko, V. M.; Gutans, Yu. A.; Korabel'nikov, Yu. G.; Pikshe, P. É.; Siluyanov, O. F.

doi:10.1007/bf00605088

Cited by 7 publications

(7 citation statements)

References 6 publications

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Section: Effect Of Filler Particle Size and Shapementioning

confidence: 98%

“…The authors of [148] proposed to express the relationship between the average fiber strength ((af>) on the "cramped" length 1 in the form:…”

Section: Effect Of Filler Particle Size and Shapementioning

confidence: 99%

“…In [148,149] it was shown that the reinforcing fiber strength distribution function is approximated with sufficient accuracy by the Weibull distribution, although there is some degree of polymodality. The average strength distribution curves (in the double logarithm coordinates) linearly depend on the "cramped" length of the fiber, decreasing as the latter increases.In [148] it was shown that the strength of the composite depends on the fiber strength at the so-called "ineffective" length, so that only a few percent of the total amount of the ineffective fiber lengths in the composite become broken before the specimen fails completely. The authors of [148] proposed to express the relationship between the average fiber strength ((af>) on the "cramped" length 1 in the form:…”

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confidence: 98%

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Filled polymers: Mechanical properties and processability

Enikolopyan

Fridman

Stal'nova

et al. 1990

Filled Polymers I Science and Technology

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In this review the wide spectrum of properties of filled polymer systems is generalized. Classical and modern conceptions dealing with the influence of the boundary layer and filler on melting and crystallization of the polymer matrix. Polymer properties in the melted and condensed state are considered, attention being given to the influence of the filler particle size and shape, the nature of its surface, its structure, and agglomeration on the theological and mechanical characteristics of composites.Data on structure and properties of filled thermoplastic composites are summarized for the first time. Special attention is paid to the peculiarities of composites with modified polymerized filler behavior during rheological and mechanical testing and processing of such composites. IntroductionPolymeric composite materials (PCM) belong to one of the most important classes of structural materials attracting ever growing interest, as manifested by the huge flow of published scientific and technical information dealing with the problems of developing, preparing, processing and using PCM [1]. Whereas the oil and gas fuel crisis has receded recently, the problem of their restrained use still remains an urgent one if only because the oil and gas reserves are not unlimited and practically non-reproducible. Estimates by specialists have shown [2,3] that the development of PCM with a view to cut the consumption of polymeric materials can only be economically feasible if not less than 15% by volume of the filler are added.Waste products from a number of commercial processes can be used as cheap and readily available fillers for PCM. For example, lightweight structural materials may be obtained by filling various low-viscous resins with waste materials [4,5]. Also by adding fillers to reprocessed polymers it is possible to improve their properties considerably and thus return them to service [6]. This method of waste utilization is not only economically feasible but also serves an ecological purpose, since it will help to protect the environment from contamination. The maximum percentage of the filler should in these cases be such as to assure reliable service of the article made from the PCM under specified conditions for a specified period of time.However, the chief purpose of introduction of fillers into PCM is to make possible the modification of polymers and thereby create materials with a prescribed set of physico-mechanical properties, and, obviously, the properties of filled materials may be controlled by, for example, varying the type of the base polymer (the "matrix") and filler, its particle size distribution and shape. It may not require a large quantity of filler [7]. Thanks to considerable advances in PCM research, their use in a broad range of industries -machine building, construction, aerospace technology, etc. -has become extensive [8][9][10][11].Development of an assortment of polymeric composite materials, decSsions concerning their possible scope of applicability and service conditions involve research in...

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Section: Effect Of Filler Particle Size and Shapementioning

confidence: 98%

“…The authors of [148] proposed to express the relationship between the average fiber strength ((af>) on the "cramped" length 1 in the form:…”

Section: Effect Of Filler Particle Size and Shapementioning

confidence: 99%

mentioning

confidence: 98%

See 1 more Smart Citation

Filled polymers: Mechanical properties and processability

Enikolopyan

Fridman

Stal'nova

et al. 1990

Filled Polymers I Science and Technology

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“…This effect is usually called the scale dependence on the fibre length. However, recall that there is a so-called lowstrength tail in the strength distribution of short fibres, too [9].…”

mentioning

confidence: 99%

“…First, the distribution of the filaments by strength is different in many cases from the Weibull distribution in the model (see, e.g., [9]). Second, experimental measurement of the strength of the individual fibres is usually possible on a base with L ≥ 10 mm, which is much greater than the ineffective (critical) length.…”

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confidence: 99%

Mechanisms of fracture and prediction of the strength of unidirectional carbon-fibre-reinforced plastics

Korabel'nikov¹

2006

Fibre Chem

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The principal difference in the mechanisms of fracture of unbound carbon fibres and reinforcing filler in unidirectional carbon-fibre-reinforced plastics does not allow predicting the strength of composites using Weibull distribution parameters and the average strength of the fibres on a standard testing base. An alternative approach that allows estimating the limiting strength of carbon fibres and the degree of its realization in a composite was repeatedly tested. The dependence of the strength realization coefficient of a reinforcing fibre on its volume content, the scaling effect of the strength, and the modulus of elasticity is given. The information required for predicting the strength of composites could be obtained from testing composites with a single fibre (SFC tests).Fundamental theoretical and experimental studies have been devoted to the mechanisms of fracture and prediction of the strength of fibre composites [1][2][3][4]. It was found that the strength and rigidity of these materials are primarily determined by the properties of the reinforcing fibres.For calculating the strength of unidirectional composites, it would seem to be sufficient to use the simple rule of mixtureswhere σ f and σ m are the strength of the reinforcing fibre and polymer matrix; V f is the volume content of fibre in the composite. However, the scale dependence of the strength on the length characteristic of thin brittle fibres results in uncertainty in the value of σ f in Eq. (1). Attempts to use the average fibre strength σ f<10> obtained from standard tests on a 10-mm base in many cases produced odd results [4,5]. The fibre strength realized in the composite σ fr = σ c /V f was frequently much higher than the average strength σ f<10> at standard length [5]. It was hypothesized in [6] that the strength of the composite coincides with the strength of a fibre bundle of length δ << 10 mm:where δ is the ineffective, more accurately [4], the critical length; α and β are Weibull distribution parameters [7] for the strength of the filaments. The hypothesis in [6] that the dependence of the fibre bundle strength on the length is the same as for a single fibre allowed using parameters α and β obtained from testing single fibres on a standard base with L = 10 mm in the calculations.Determining critical length δ in Eq.(2) is recommended in [3] using the KellyTyson equation for a plastic matrix [8]:where σ f is the strength of a fibre of length l; d f is the diameter of the fibre; τ m is the shear strength between fibre and matrix polymer.

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