scholarly journals Evaluation of In-Plane Mode II Fracture Toughness in Unidirectional GFRP Using Four-Point Shear Loading Test. Revised Test Method and Dependence of the Pre-Crack Length.

1993 ◽  
Vol 42 (478) ◽  
pp. 817-822
Author(s):  
Hiroyuki KAWADA ◽  
Hiroshi SHIMANUKI ◽  
Hideo OMATA ◽  
Ikuhiko HAYASHI
Keyword(s):  
Fracture Toughness ◽  
Crack Length ◽  
Shear Loading ◽  
Test Method ◽  
Mode Ii ◽  
Loading Test ◽  
Mode Ii Fracture ◽  
Mode Ii Fracture Toughness ◽  
Plane Mode

Experimental Investigation on Mode II Fracture Toughness KIIC of Concrete and Fracture Behavior

2006 ◽  
Vol 324-325 ◽  
pp. 1149-1152 ◽  
Author(s):  
Shi Lang Xu ◽  
Hong Bo Gao ◽  
Xiu Fang Zhang
Keyword(s):  
Fracture Toughness ◽  
Crack Length ◽  
Fracture Behavior ◽  
Shear Fracture ◽  
Discontinuity Point ◽  
Fracture Load ◽  
Mode Ii ◽  
Mode Ii Fracture ◽  
Double Edge ◽  
Mode Ii Fracture Toughness

Using the double-edge notched geometry proposed by Xu and Reinhardt recently, the dimension of 200 mm×200 mm×100mm concrete cube specimens, of which the crack length are 10 mm, 20 mm, 30mm, 40mm, 50mm respectively, are designed to experimentally measure mode II fracture toughness KIIC of concrete. For almost all specimens, typical shear fracture features i.e. approximately 0º initial cracking angle as well the following crack forwards propagation along the direction of ligament is phenomenally observed. This fact strongly confirms that this double-edge notched geometry is validly and capable of being utilized as a mode II fracture geometry to evaluate mode II fracture behavior. Then, from the discontinuity point of the measured load-displacement plot, the critical shear fracture load Pc is determined and the corresponding mode II fracture toughness KIIC is also calculated using the formula developed by Xu and Reinhardt. The computed results show that KIIC has no dependency on initial crack length, about 3.36MPa·m1/2 for the tested specimens.

An Investigation of the End-Notched Flexure and End-Loaded Split Tests Applied to the Mode II Interlaminar Fracture of a SiC/SiC Ceramic Matrix Composite

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Michael J. Presby ◽  
Manigandan Kannan ◽  
Gregory N. Morscher ◽  
Cody Godines ◽  
Amirhossein Eftekharian ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Test Methods ◽  
Test Method ◽  
Image Correlation ◽  
Mode Ii ◽  
Shear Stresses ◽  
Mode Ii Fracture ◽  
Mode Ii Fracture Toughness

Abstract Delamination is a common failure mode observed in ceramic matrix composites (CMCs) and occurs as a result of applied interlaminar tensile and shear stresses exceeding the interlaminar strength. As CMCs are further implemented into aero engines, the need to understand their interlaminar failure becomes increasingly important. While significant contributions have been made toward understanding the mode I fracture toughness of CMCs, limited work exists on mode II. Several test methods for measuring the mode II fracture toughness have been proposed in the literature, namely, the end-notched flexure (ENF) and the end-loaded split (ELS) tests. This work investigates the mode II fracture toughness of a melt-infiltrated SiC/SiC CMC at ambient temperature using the ENF and ELS test methods. Acoustic emission (AE), direct current potential drop (DCPD), and digital image correlation (DIC) are implemented as health monitoring techniques to monitor crack initiation and propagation. Results show reasonable correlation between the two test methods and that the ELS test method is better suited for characterizing R-curve behavior.

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.

An Investigation of the End-Notched Flexure and End-Loaded Split Tests Applied to the Mode II Interlaminar Fracture of a SiC/SiC Ceramic Matrix Composite

2019 ◽  
Author(s):  
Michael J. Presby ◽  
K. Manigandan ◽  
Gregory N. Morscher ◽  
Cody Godines ◽  
Amir Eftekharian ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Test Methods ◽  
Test Method ◽  
Image Correlation ◽  
Mode Ii ◽  
Shear Stresses ◽  
Mode Ii Fracture ◽  
Mode Ii Fracture Toughness

Abstract Delamination is a common failure mode observed in ceramic matrix composites (CMCs) and occurs as a result of applied interlaminar tensile and shear stresses exceeding the interlaminar strength. As CMCs are further implemented into aero engines the need to understand their interlaminar failure becomes increasingly important. While significant contributions have been made toward understanding the mode I fracture toughness of CMCs, limited work exists on mode II. Several test methods for measuring the mode II fracture toughness have been proposed in literature, namely the end-notched flexure (ENF) and the end-loaded split (ELS) tests. This work investigates the mode II fracture toughness of a melt-infiltrated SiC/SiC CMC at ambient temperature using the ENF and ELS test methods. Acoustic emission (AE), direct current potential drop (DCPD), and digital image correlation (DIC) are implemented as health monitoring techniques to monitor crack initiation and propagation. Results show reasonable correlation between the two test methods and that the ELS test method is better suited for characterizing R-curve behavior.

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.

Sign in / Sign up

Export Citation Format

Share Document