Mode II fracture toughness testing of a fiber-reinforced ceramic composite

Delamination is one of the important damage modes in the fiber-reinforced composite laminates. The interlaminar fracture toughness is the key parameter in delamination failure analysis of composites. The stress analysis by a finite element modeling has shown that the shear stress is very large near the ply splicing area. So the delamination failure is mainly dependent on the mode II fracture toughness. A new way of loading in tensile testing is proposed for the measurement of mode II fracture toughness. Specific specimen with splicing plies has been designed and used for the experiment. Testing study on the carbon-fiber-reinforced laminate with ply splicing was performed. Steady crack propagation has been seen by the tensile testing of the specimen. Mode II fracture toughness GIIC of the laminate has been determined by the experiment data analysis. The experiment and numerical analysis shows that the tensile testing for the measurement of mode II interlaminar fracture toughness is feasible.

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High-rate mode II fracture toughness testing of polymer matrix composites using the Transverse Crack Tension (TCT) test

Composites Part B Engineering ◽

10.1016/j.compositesb.2022.109636 ◽

2022 ◽

pp. 109636

Author(s):

Philipp Hahn ◽

Harichandana Channammagari ◽

Mathieu Imbert ◽

Michael May

Keyword(s):

Fracture Toughness ◽

Polymer Matrix ◽

Transverse Crack ◽

Polymer Matrix Composites ◽

High Rate ◽

Mode Ii ◽

Matrix Composites ◽

Fracture Toughness Testing ◽

Mode Ii Fracture Toughness ◽

Toughness Testing

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Environmental effects on mode II fracture toughness of unidirectional E-glass/vinyl ester laminated composites

Science and Engineering of Composite Materials ◽

10.1515/secm-2021-0028 ◽

2021 ◽

Vol 28 (1) ◽

pp. 382-393

Author(s):

Mazaher Salamt-Talab ◽

Fatemeh Delzendehrooy ◽

Alireza Akhavan-Safar ◽

Mahdi Safari ◽

Hossein Bahrami-Manesh ◽

...

Keyword(s):

Fracture Toughness ◽

Sulfuric Acid ◽

Vinyl Ester ◽

Cohesive Zone Model ◽

Flexural Modulus ◽

Mode Ii ◽

Zone Model ◽

Sharp Drop ◽

Mode Ii Fracture ◽

Mode Ii Fracture Toughness

Abstract In this article, mode II fracture toughness ( G IIc {G}_{\text{IIc}} ) of unidirectional E-glass/vinyl ester composites subjected to sulfuric acid aging is studied at two different temperatures (25 and 90°C). Specimens were manufactured using the hand lay-up method with the [ 0 ] 20 {{[}0]}_{20} stacking sequence. To study the effects of environmental conditions, samples were exposed to 30 wt% sulfuric acid at room temperature (25°C) for 0, 1, 2, 4, and 8 weeks. Some samples were also placed in the same solution but at 90°C and for 3, 6, 9, and 12 days to determine the interlaminar fracture toughness at different aging conditions. Fracture tests were conducted using end notched flexure (ENF) specimens according to ASTM D7905. The results obtained at 25°C showed that mode II fracture toughness increases for the first 2 weeks of aging and then it decreases for the last 8 weeks. It was also found that the flexural modulus changes with the same trend. Based on the results of the specimens aged at 90°C, a sharp drop in fracture toughness and flexural modulus with a significant decrease in maximum load have been observed due to the aging. Finite element simulations were performed using the cohesive zone model (CZM) to predict the global response of the tested beams.

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Displacement Rate Effects on the Mode II Shear Delamination Behavior of Carbon Fiber/Epoxy Composites

Polymers ◽

10.3390/polym13111881 ◽

2021 ◽

Vol 13 (11) ◽

pp. 1881

Author(s):

Kean Ong Low ◽

Mahzan Johar ◽

Haris Ahmad Israr ◽

Khong Wui Gan ◽

Seyed Saeid Rahimian Koloor ◽

...

Keyword(s):

Fracture Toughness ◽

Peak Load ◽

Epoxy Composites ◽

Displacement Rate ◽

Interface Debonding ◽

Mode Ii ◽

Scanning Electron Micrographs ◽

Unstable Crack ◽

Mode Ii Fracture ◽

Mode Ii Fracture Toughness

This paper studies the influence of displacement rate on mode II delamination of unidirectional carbon/epoxy composites. End-notched flexure test is performed at displacement rates of 1, 10, 100 and 500 mm/min. Experimental results reveal that the mode II fracture toughness GIIC increases with the displacement, with a maximum increment of 45% at 100 mm/min. In addition, scanning electron micrographs depict that fiber/matrix interface debonding is the major damage mechanism at 1 mm/min. At higher speeds, significant matrix-dominated shear cusps are observed contributing to higher GIIC. Besides, it is demonstrated that the proposed rate-dependent model is able to fit the experimental data from the current study and the open literature generally well. The mode II fracture toughness measured from the experiment or deduced from the proposed model can be used in the cohesive element model to predict failure. Good agreement is found between the experimental and numerical results, with a maximum difference of 10%. The numerical analyses indicate crack jump occurs suddenly after the peak load is attained, which leads to the unstable crack propagation seen in the experiment.

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