scholarly journals Evaluation of Mode II Fracture Toughness in Unidirectional GFRP Using Four-Point Shear Loading Test and Its Fracture Mechanism.

1991 ◽  
Vol 40 (454) ◽  
pp. 875-881
Author(s):  
Hiroyuki KAWADA ◽  
Yutaka OCHI ◽  
Hiroshi SHIMANUKI ◽  
Ikuhiko HAYASHI
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanism ◽  
Shear Loading ◽  
Mode Ii ◽  
Loading Test ◽  
Mode Ii Fracture ◽  
Mode Ii Fracture Toughness

Research on the KII C of the Two Types of Concrete Specimens

2012 ◽  
Vol 157-158 ◽  
pp. 1260-1263
Author(s):  
Ai Min Deng ◽  
Dao Yuan Xu ◽  
Wei Xuan Zhu
Keyword(s):  
Fracture Toughness ◽  
Fracture Process ◽  
Process Zone ◽  
Pure Shear ◽  
Shear Loading ◽  
Mode Ii ◽  
Mode Ii Fracture ◽  
Mode Ii Fracture Toughness ◽  
The Difference ◽  
Displacement Extrapolation Method

According to the mode II fracture test results of the concrete of the double-edge notched specimens with four-point shear loading and half symmetrical loading, the relationship of the mode II fracture toughness of two type of concrete specimens are analyzed. Based on the numerical simulation, the stress field near the crack tip is analyzed by use of the finite element method, and the mode II fracture toughness of the two types of concrete specimens are calculated with the displacement extrapolation method, and the difference with the experimental results are studied. Because of the uniform stress of the specimen with half symmetric loading, and the shear stress in the fracture process zone is much larger than the first principal stress during the entire test process, while the phenomenon of opening and torsion of the surface of cracks may appeared at the four point shear loading conditions, which leads to the fracture process of the specimen is not always the mode II fracture of pure shear.

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

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.

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

Polymers ◽  
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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