The influence of temperature and moisture on the mode I fracture toughness and associated fracture morphology of a highly toughened aerospace CFRP

Katafiasz, T.J.; Greenhalgh, Emile S.; Allegri, Giuliano; Pinho, S.T.; Robinson, P.

doi:10.1016/j.compositesa.2020.106241

Cited by 32 publications

(14 citation statements)

References 14 publications

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“…The three-dimensional fracture surfaces visualized in figure 10, together with the fibre pull-out height distributions shown in figures 11 and 12, show that higher testing temperature led to a more extensive development of fibre pull-out, with more fibres protruding from the global crack plane and larger pull-out heights. The larger heights are consistent with the increasing trend of translaminar fracture toughness, and the mechanism can be explained as follows: (i) the exposure of composites to elevated temperatures can severely undermine the fibre/matrix interface (as evidenced by SEM images of the fibre/matrix interface [4,26,27]); (ii) weaker interfaces, in turn, provide less resistance to the interfacial debonding and subsequent pull-out process; (iii) therefore, longer pull-out lengths develop on the fracture surfaces formed under higher temperatures, which ultimately leads to a higher energy dissipation.…”

Section: (C) Model Validation For Translaminar Fracture Toughnesssupporting

confidence: 66%

Characterizing and predicting the relationship between translaminar fracture toughness and pull-out length distributions under distinct temperatures

Katafiasz

Nguyen

et al. 2022

Phil. Trans. R. Soc. A.

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The translaminar fracture toughness reflects the damage tolerance of a fibre-reinforced composite under longitudinal tension, which often governs the final failure of structures. One of the main energy-dissipation mechanisms that contributes to the translaminar toughness of composites is the fibre pull-out process. The present study aims to quantify and model the statistical distribution of fibre pull-out lengths formed on the translaminar fracture surface of composites, for the first time in the literature; this is done under different temperatures, so that the relationship between pull-out length distributions, micromechanical properties and the translaminar fracture toughness can be established. The fracture surfaces of cross-ply compact tension specimens tested under three different temperatures have been scanned through X-ray computed tomography to quantify the extent of fibre pull-out on the fracture surfaces; the distribution of pull-out lengths showed alarger average and larger variability with an increase in temperature, which also lead to an increase in translaminar fracture toughness. A similar trend has been captured by the proposed analytical model, which predicts the pull-out length distribution based on the analysis of quasi-fractal idealizations of the fracture surface, yielding an overall accuracy of more than 85%. This article is part of the theme issue 'Ageing and durability of composite materials'.

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Section: (C) Model Validation For Translaminar Fracture Toughnesssupporting

confidence: 66%

Characterizing and predicting the relationship between translaminar fracture toughness and pull-out length distributions under distinct temperatures

Katafiasz

Nguyen

et al. 2022

Phil. Trans. R. Soc. A.

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“…This can be well illustrated by the pictures of side edges in Figure 7C, which shows the captured states of bridging fibers in specimens at the same magnification while at different temperatures. It can be seen that more bridging fibers present in the wake of the crack tip at 130°C than that at 80°C, which indicates the weakening of the fiber–matrix interface at high temperature 37 . The initial fracture toughness increases with temperature significantly, showing its sensitivity to the temperature.…”

Section: Experimental Results Of Dcb Tests At Different Temperaturesmentioning

confidence: 94%

“…It can be seen that more bridging fibers present in the wake of the crack tip at 130 C than that at 80 C, which indicates the weakening of the fiber- matrix interface at high temperature. 37 The initial fracture toughness increases with temperature significantly, showing its sensitivity to the temperature. This may be resulted by the increase in the matrix ductility and the associated ability to dissipate more energy.…”

Section: Experimental R-curve Behaviormentioning

confidence: 96%

“…Boni et al 36 conducted mode I delamination tests on Hexcel 913c-HTA specimens at room temperature and 70 C. Test results show that the resin exhibits a more plastic and ductile behavior and the fracture toughness increases with the increase of temperature. Katafiasz et al 37 measured the mode I fracture toughness of thermoplastic interleaved aerospace CFRP dry laminates, at 19 C and 90 C. They observed the high level of ductility in all phases within the ply interlayers at 90 C, which results in 37% increase of the fracture toughness than that at room temperature.…”

Section: Introductionmentioning

confidence: 99%

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Temperature effect on the static mode I delamination behavior of aerospace‐grade composite laminates: Experimental and numerical study

Gong

Jiang

et al. 2022

Fatigue Fract Eng Mat Struct

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Aerospace structures are exposed to high‐temperature conditions during service. In‐depth study for the temperature effect on composite interlaminar properties is important for the structural design and reliable application. In this study, mode I delamination behaviors at different temperatures are investigated, to understand the effects of temperature on the delamination growth process, including fracture toughness, bridging stress, and failure mechanism. It is found that R‐curve behavior presents at all temperatures. The initial and steady‐state fracture toughnesses exhibit linear increase trends with the increase of the temperature, from which equations are established to predict the initial and steady‐state fracture toughnesses at other temperatures. More bridging fibers are observed at higher temperatures, and the resulted fracture resistance at 130°C is 136.9% higher than that at room temperature. The maximum bridging stress also increases with the increase of temperature. A numerical framework based on the cohesive zone model is established for delamination modeling. Material parameters at various temperatures are obtained by an exponential model. Suitable values of interfacial parameters in cohesive elements are numerically determined. Predicted load–displacement responses agree well with the experimental ones, illustrating the applicability of the proposed numerical method.

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“…Another line of work in this eld analyzes under different bre orientations of the composite material [39], also the behaviour of adhesive joints in composite materials subjected to different degradation processes such as humidity and its effects on the delamination process under pure fracture modes [40], exposure to a saline environment [41,42], freezing and thawing [43], water absorption in joints with hybrid composite materials [44], the effects of temperature [45][46][47] and the combination of the effects of humidity and temperature [48][49][50].…”

Section: Introductionmentioning

confidence: 99%

Study of the fatigue delamination behaviour of adhesive joints in carbon fibre reinforced epoxy composites, influence of the period of exposure to saline environment

Argüelles

Viña

Vigón

et al. 2022

Preprint

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This work analyses the fatigue delamination and fracture stress behaviour under mode I of adhesive joints made on an epoxy matrix composite material with unidirectional carbon fibre reinforcement and a commercial epoxy-based adhesive. DCB type tests (for mode I) were used with the aim to quantify the influence of the period of exposure to a degradation process in a salt spray chamber, to which the tested samples were subjected, on their fatigue behaviour. For this purpose and after a previous static characterisation of the material in which the critical values of the energy release rate for different exposure periods were determined, the levels of the energy release rate (ERR) to be applied in the fatigue tests and the exposure periods to be considered (no exposure, exposure during one week and twelve weeks) and a ratio of fatigue stress levels of R = Gmin/Gmax=0.1 were defined. From this experimental data, the G-N fatigue initiation curves and the G-da/dN growth curves were obtained. The experimental data obtained, in the fatigue initiation phase of the delamination process, have been treated by means of a probabilistic model based on a Weibull distribution, the application of models of these characteristics has allowed a better interpretation of the experimental results obtained. The most relevant result of the work is that, in general, the fatigue limits obtained for the adhesive joint, under mode I fracture, when subjected to a degradation process in a saline environment, do not translate into a relevant loss of its resistance capacity against this fatigue delamination phenomenon, in its initiation phase. On the other hand, the crack growth rates of the material subjected to different periods of exposure to a saline environment are similar and higher than those obtained for the material without exposure.

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The influence of temperature and moisture on the mode I fracture toughness and associated fracture morphology of a highly toughened aerospace CFRP

Cited by 32 publications

References 14 publications

Characterizing and predicting the relationship between translaminar fracture toughness and pull-out length distributions under distinct temperatures

Characterizing and predicting the relationship between translaminar fracture toughness and pull-out length distributions under distinct temperatures

Temperature effect on the static mode I delamination behavior of aerospace‐grade composite laminates: Experimental and numerical study

Study of the fatigue delamination behaviour of adhesive joints in carbon fibre reinforced epoxy composites, influence of the period of exposure to saline environment

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