Modeling and Testing the Fracture Process of Impregnated Carbon-fiber Roving Specimens During Bending: Part II – Experimental Studies

Vas, László Mihály; Rácz, Zsolt; Nagy, Péter

doi:10.1177/0021998304044768

Cited by 8 publications

(18 citation statements)

References 2 publications

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“…With the above results, the breaking process of the ES-bundle according to Equation (33) can be rewritten:…”

Section: Expected Breaking Process Of the Modified Es-bundlementioning

confidence: 99%

“…Based on the fiber flow theory [1,3,4,10] and the method of fiber-bundle-cells developed by Vas and co-workers [18,20,22,23,32,33], this study aims at developing new statistical models and describing the breaking process of fibrous structures up to total damage, as well as finding simple formulas for the relationship between the tensile strength and the fiber length with special attention to the constant fiber length.…”

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confidence: 99%

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Strength of Unidirectional Short Fiber Structures as a Function of Fiber Length

Vas

2006

Journal of Composite Materials

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The strength of super-oriented polymer fibers or unidirectional short fiber composites strongly depends on the length of the molecule chains or the reinforcing fibers, respectively. A simple statistical model is developed based on the theory of fiber flows and the strength of the structure and its dependence on fiber length are determined in case of fibers broken or damaged owing to parting rigidly from the environment simultaneously. Later, two new special and modified versions of the so-called ES-bundle and one of the idealized statistical fiber-bundlecells developed earlier, are introduced and applied to model the breaking process of the fibrous structure at different damage modes and its dependence on the fiber length is analyzed. In case of constant fiber length, a simple analytical relationship between the mean tensile strength and the fiber length is obtained which is valid for all the cases discussed. On the basis of the results, formulas are developed to estimate the strength of short fiber composites as a function of fiber length and fiber content, as well as to model the effect of the reduction in the fiber adhesion in case of a very small matrix content. The practical applicability of the results is demonstrated by identifying the relationship between tensile strength and molecule mass of PP fibers.

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“…With the above results, the breaking process of the ES-bundle according to Equation (33) can be rewritten:…”

Section: Expected Breaking Process Of the Modified Es-bundlementioning

confidence: 99%

mentioning

confidence: 99%

Strength of Unidirectional Short Fiber Structures as a Function of Fiber Length

Vas

2006

Journal of Composite Materials

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“…The 9% deformation tests were passed by each pipe except for 4PI and 6PI and the 15% deformation tests were failed by each pipe except for 1PI, 3PI, 5PI, 10PI, 11PI, 15PI and 16PI. The failure type of the composite ring specimens was typically delamination [15,16] (Fig. 12).…”

Section: Resultsmentioning

confidence: 99%

Development and Analysis of New Filament Wound Composite Pipes Made of Glass Fiber Reinforced 3P Resin

Czél

Czigány

2006

Macromolecular Symposia

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Summary: Filament wound composite pressure pipes made of newly developed 3P, various hybrid and reference resin materials and glass fiber filaments were investigated. 3P resins consist of soluble silicates, polyisocyanates and other additives, they are flame and chemical resistant, and capable of curing under wet conditions. Tensile strengths, tensile moduli and effective moduli values obtained from ring stiffness tests were evaluated. Properties of pipe types made of new resin materials were compared to those made of reference resins. A special tensile specimen fabricating process and a cross sectional area calculating method was presented. The calculation method is capable of handling the geometric inaccuracies of specimen prefabrication steps e.g. cutting. Evaluated material properties were discussed by defining dimensionless performance factors. Pipes were classified according to these performance factors and the suitability of the new resin materials for composite pressure pipe manufacturing was established. The best newly developed matrix materials were the 16905 type vinylester-3P hybrid and 16907 type vinylesterurethane hybrid resins, because of their outstanding mechanical properties.

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“…This paper presents a statistical fiber-bundle-cells [55][56][57][58][59][60][61] based novel modeling and evaluating method for classifying and characterizing AE signals, which can manage overlaps in histograms or spectrums by the simultaneous decomposition of the stress-strain curve, the cumulative number of AE events and any cumulative statistics of AE descriptors. The fitted FBC model makes it possible to analyze the mechanical reliability of the material and construct a kind of damage map for characterizing the failure behavior.…”

Section: Objectivesmentioning

confidence: 99%

“…The FBC modeling method is based on some idealized statistical fiber bundles called fiberbundle-cells (FBCs) which can be used as building elements of a model network created by parallel and/or serial connections. [55][56][57][58][59] Idealized fiber bundles are defined as fiber classes containing fibers of the same geometrical (shape, disposition) and mechanical properties (strain state, gripping by the surroundings) ( Figure 2). In the simplest case, the fibers are ideally elastic (E) with a linear or non-linear relationship between the strain and load, although they break at a random strain value.…”

Section: Statistical Fiber-bundle-cells (Fbcs)mentioning

confidence: 99%

Novel evaluation method of acoustic emission data based on statistical fiber bundle cells

Vas

Kocsis²,

Czigány

et al. 2019

Journal of Composite Materials

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In general, the aim of acoustic emission (AE) assisted tensile tests of composite materials is to identify and characterize the damage and failure modes of the specimens. This paper presents a fiber-bundle-cells (FBC) based statistical model, which provides a possible solution to the problem of characterizing the mechanical and failure behavior of the material. The model, based on the results of mechanical tests and AE measurements, decomposes the measured AE event number and tensile force-load time processes into components corresponding to the different damage modes. The AE events belonging to different failure modes are described by inhomogeneous Poisson point processes, while failures are modeled with the breakage of fibers as elementary parts of the sample. Hence damage modes can be characterized with the number fraction, and the tensile strength and signal energy distributions of the components. Moreover, the variation of the number fraction of the intact or damaged fibers as a function of the load time can be calculated and depicted as well. As reliability function or a kind of damage map, it reveals the mechanical load-bearing ability of the material tested. The applicability of the model is demonstrated by compact tension testing and the comparison of short and long glass fiber reinforced VERTON PP sheets and injection molded wood fiber reinforced PP composites.With the help of fast Fourier transformation (FFT), the frequency components of the single AE signals can be characterized by the amplitude or power spectrum in the frequency domain. Their description parameters are the bandwidth (B), the mean frequency (fm), the frequency of the maximum amplitude component (fP), and the amplitude (AP) or energy (UP) of the maximum peak. Similar parameters can be obtained from the mean spectra of a series of AE signals, and histograms and/or cross-plots can be calculated from the data of single AE signals. 2,4 Special techniques can provide information in both the time and the frequency domain, resulting in time-dependent spectrum statistics. 2,4 The classic method is the short time FFT (SFFT) technique, which uses a moving time window. In the case of wavelet transformations (WT), AE signals are analyzed with the help of various wavelet components. The signal transformations mentioned above provide additional or in itself usable information about the sources and failure modes in the frequency domain [21][22][23][24][25][26] or both in the time and the frequency domains [27][28][29][30][31][32][33][34][35][36] . In the latter case, wavelet transformations based on Haar 28 or Gabor 27, 33 wavelet components as well as Hilbert-Huang transform 30 can be used to decompose the AE signals and calculate the energy of the components. [27][28][29][30][31][32][33][34][35][36] In the case of thin plates, modal analysis can be applied to study and separate extensional and flexural Lamb waves. 37,38 The finite element method (FEM) can give a good base for wave discrimination. 38 The localization of a single AE signal in the spe...

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Modeling and Testing the Fracture Process of Impregnated Carbon-fiber Roving Specimens During Bending: Part II – Experimental Studies

Cited by 8 publications

References 2 publications

Strength of Unidirectional Short Fiber Structures as a Function of Fiber Length

Strength of Unidirectional Short Fiber Structures as a Function of Fiber Length

Development and Analysis of New Filament Wound Composite Pipes Made of Glass Fiber Reinforced 3P Resin

Novel evaluation method of acoustic emission data based on statistical fiber bundle cells

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