Comparison of R-Curves from Single-Edge V-Notched-Beam (SEVNB) and Surface-Crack-in-Flexure (SCF) Fracture-Toughness Test Methods on Multilayered Alumina-Zirconia Composites

Using a variety of advanced ceramic materials, a comparison has been conducted of fracture toughness test methods using the single edge vee-notch beam method and the surface crack in flexure method, the latter restricted to optical fractography. Good agreement has been found between the two methods on materials which were amenable to the SCF method. It has further been shown that the SEVNB method can produce reliable results on materials to which the SCF method is not readily applicable.

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Assessing Low-Constraint Fracture Toughness Test Methods Using Clamped SENT Specimens

Volume 6A: Materials and Fabrication ◽

10.1115/pvp2019-93088 ◽

2019 ◽

Author(s):

Xian-Kui Zhu ◽

Tom McGaughy

Keyword(s):

Fracture Toughness ◽

Oil And Gas ◽

Oil And Gas Industry ◽

Test Methods ◽

Fracture Toughness Test ◽

Single Edge ◽

Gas Industry ◽

End Conditions ◽

The Difference ◽

Low Constraint

Abstract The low-constraint fracture toughness can be measured using a single edge-notched tension (SENT) specimen in the clamped-end conditions. The SENT specimen has been used in the oil and gas industry in the strain-based design and the crack assessment for transmission pipelines. Since 2006 when DNV published the first SENT test practice, many investigations have been done, and various SENT test methods were developed, including CANMET and ExxonMobil methods in terms of the J-integral and CTOD. The effort led to the first SENT test standard BS 8571 being published in 2014. However, the experimental evaluation methods remain in developing, and different methods may determine inconsistent results. For this reason, the present paper gives a brief review on SENT fracture testing and assesses the available test methods, including progresses on study of stress intensity factor, geometric eta factors, elastic compliance equation, and constraint m factor as well. The difference between J-converted CTOD and double clip gage measured CTOD is also discussed. On those bases, agreements and challenges in SENT testing are identified. The results provide a direction for further investigation to improve the current SENT test methods.

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Single Edge Precrack V-Notched Beam (SEPVNB) Fracture Toughness Testing on Silicon Nitride

Materials Science Forum ◽

10.4028/www.scientific.net/msf.962.205 ◽

2019 ◽

Vol 962 ◽

pp. 205-209

Author(s):

Tjokorda Gde Tirta Nindhia ◽

Tanja Lube

Keyword(s):

Fracture Toughness ◽

Silicon Nitride ◽

Crack Size ◽

Fracture Toughness Test ◽

Single Edge ◽

Razor Blade ◽

Sintered Ceramic ◽

Toughness Test ◽

Toughness Testing ◽

Diamond Paste

The previous Measurement of fracture toughness test by using bright indentation for precracked beam method (ASTM C1421) was found difficult to be carried out due to difficulty in precrack generation and measurement of the crack size. In this research single edge precrack V-notch beam (SEPVNB) is introduced as an alternative to solve the problem from previous standardized method. A real crack that can created with referred size is recognized as the best condition for fracture toughness test. The material prepared for this purpose was silicon nitride (Si3N4) produced by CeramTec (Plochingen, Germany) under the name SL200 B. It is a gas pressure sintered ceramic containing 3 wt.% Al2O3 and 3 wt.% Y2O3. The V Notch was prepared by using razor blade with diamond paste following ISO/FDIS 23146 standard preparation with more addition on precrack introduction. The precrack was introduced by so called opposite roller loading. The fracture toughness test was carried out by following procedure in ISO/FDIS 23146 . The result then was compared for validation with both single edge V-notch beam standard (ISO/FDIS 23146 ) and Surface crack in Flexure SCF (ASTM C 1421). The result of fracture toughness by using method that is introduce in this research is found 5.8270.275 MPa1/2 which is close to the result of SCF (5.335 0.222 MPa1/2). Meanwhile the value of fracture toughness by using V-notch beam is 4.9130.098 MPa1/2

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