A micromechanical model for prediction of mixed mode I/II delamination of laminated composites considering fiber bridging effects

Daneshjoo, Z.; Shokrieh, M.M.; Fakoor, Mahdi

doi:10.1016/j.tafmec.2017.12.002

Cited by 42 publications

(19 citation statements)

References 27 publications

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“…Accordingly, the critical load values for the onset of delamination growth based on the critical SED approach ( − P ini SED ) can be determined through Eq. (17). The results obtained by numerically solving Eqs.…”

Section: Resultsmentioning

confidence: 99%

“…This link would enable a better understanding of delamination failure, which could lead to design lighter load-bearing composite structures. In a number of research studies available in the literature, researchers [11][12][13][14][15][16] have tried to connect the macroscopic description of delamination through the SERR with the microscopic damage features, as discussed elsewhere [17,18]. To this aim, they used the SERR and fractography on the mode I and mode II interlaminar fracture surfaces to investigate the effect of different parameters such as the mode mixity, resin toughness and resin layer thickness in the delamination resistance.…”

Section: Introductionmentioning

confidence: 99%

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Physics of delamination onset in unidirectional composite laminates under mixed-mode I/II loading

Daneshjoo

Shokrieh

Fakoor

et al. 2019

Engineering Fracture Mechanics

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A B S T R A C TIn order to understand the physics of the delamination onset in laminated composites, an experimental investigation of delamination growth is presented. The main objective of this paper is to demonstrate that delamination onset occurs at lower values than G c defined by the ASTM standards, and that the strain energy release rate level at which the crack growth onset occurs under any mixed mode I/II loading is governed by the critical strain energy density (SED) approach. Quasi-static delamination experiments have been performed under mode I, mode II and mixed mode I/II loadings. The value of the strain energy release rate at the observed crack onset and the angle of the initial crack growth were correlated with the SED theory to test the validity. The acoustic emission was also used to provide more insight into the physics of the delamination growth. The investigation shows that the onset of delamination growth occurs at the strain energy release rate levels predicted by the critical SED approach, and well before reaching the critical strain energy release rate determined via delamination tests following the ASTM standards. Moreover, results indicated that the predicted angle of the initial crack for delamination onset was in a good agreement with the experimental data. linearity (NL), the point at which the delamination growth is visually observed (VIS) or the intersection of a 5% offset line (5% Max).

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Physics of delamination onset in unidirectional composite laminates under mixed-mode I/II loading

Daneshjoo

Shokrieh

Fakoor

et al. 2019

Engineering Fracture Mechanics

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“…Hence, there is a need to further our knowledge of the damage mechanisms involved in the process and the quantification of the strength of the material subject to this phenomenon. Numerous test methods have been developed for this purpose, all of which are based on fracture mechanics, in pure mode fracture [1,2,3,4] as well as mixed mode fracture [5,6,7,8,9]. The most widely used mixed mode I/II test in the field standardized by ASTM is known as the mixed-mode bending (MMB) test [10].…”

Section: Introductionmentioning

confidence: 99%

Influence of the Test Method on the Characterization of the Fatigue Delamination Behavior of a Composite Material under Mixed Mode I/II Fracture

et al. 2019

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Composite materials manufactured by overlapping plies with certain specific geometries are likely to lose part of their strength due to the presence of internally delaminated regions. The aim of this paper is to experimentally evaluate the generation and propagation of these interlaminar cracks in a carbon-epoxy composite material subjected to fatigue loading under mixed mode I/II fracture. Two different test methods were used for this purpose: The standardized mixed-mode bending (MMB) test and the asymmetric double cantilever beam (ADCB) test, with the goal of exploring the viability of the ADCB test as a simpler alternative to perform than the MMB test, especially in fatigue testing. With this aim in mind and after prior static characterization of the material in which the critical values of the energy release rate were determined under both test methods, the levels of the energy release rate to be applied in fatigue tests were defined for two mode mixity ratios, GII/Gc = 0.2 and 0.4 (0.34 ADCB), and a fatigue loading ratio, R = Gmin/Gmax = 0.1. The G-N fatigue onset curves were subsequently obtained from these experimental data. The most relevant result of the study is that the fatigue limits obtained using the MMB method are generally more conservative than those obtained via the ADCB method.

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“…This level is then referred to as the fracture toughness for onset of delamination growth [7]. As pointed out in earlier work [17,18], there seems to be a gap between this macroscopic description of delamination through the onset SERR and the micromechanisms acting during the onset of fracture. Several researchers [19][20][21] have tried to relate the observed microscopic damage features with the macroscopic behaviour of damage growth.…”

Section: Connecting Micromechanisms and Macroscopic Damage Growthmentioning

confidence: 99%

Development of a physics-based theory for mixed mode I/II delamination onset in orthotropic laminates

Daneshjoo

Amaral

Alderliesten

et al. 2019

Theoretical and Applied Fracture Mechanics

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This paper demonstrates how the critical strain energy density in the delamination tip vicinity may be used to explain the physics of delamination growth under mixed mode I/II. A theory previously proposed to physically relate mode I and mode II delamination growth is further extended towards describing the onset of mixed mode I/II delamination. Subsequently, data from the literature is used to demonstrate that this new concept of the critical strain energy density approach indeed explains, based on the physics of the problem, the strain energy release rate level at which crack onset occurs. This critical strain energy density for the onset of delamination appears to be independent of the opening mode. This means that, in order to characterize the fracture behaviour of a laminate, fracture tests at only one loading mode are necessary. Because the load level at which the physical delamination onset occurs at the microscopic level is much lower than the traditional engineering definition of macroscopic onset, further work must reveal the relationship between the macroscopically visible delamination onset, and the microscopic onset.

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A micromechanical model for prediction of mixed mode I/II delamination of laminated composites considering fiber bridging effects

Cited by 42 publications

References 27 publications

Physics of delamination onset in unidirectional composite laminates under mixed-mode I/II loading

Physics of delamination onset in unidirectional composite laminates under mixed-mode I/II loading

Influence of the Test Method on the Characterization of the Fatigue Delamination Behavior of a Composite Material under Mixed Mode I/II Fracture

Development of a physics-based theory for mixed mode I/II delamination onset in orthotropic laminates

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