Improved normalization method for ductile fracture toughness determination based on dimensionless load separation principle

Bao, Chen; Liu, Cai; Shi, Kun; Chen, Dan; Yao, Yao

doi:10.1016/s0894-9166(15)30005-7

Cited by 14 publications

(14 citation statements)

References 15 publications

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“…For fracture toughness value estimation, the blunting line was constructed by J = Mσ Y ∆a, in which the expression of a value of 2 or 4 for M was used to determine J Q value [10,17]. Meanwhile, it was reported that the slope of the blunting line (Mσ Y ) for determination of J Q may not affect when the ratio of yield strength (σ YS ) to tensile strength (σ UTS ) is close to 1 [18]. As summarized in Table 2, the calculation result of σ YS /σ UTS at 700 • C is 0.95, which is almost 1.…”

Section: Fracture Toughness Test Resultsmentioning

confidence: 99%

Measurement of Fracture Toughness of Pure Tungsten Using a Small-Sized Compact Tension Specimen

et al. 2020

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The evaluation of fracture toughness of pure tungsten is essential for the structural integrity analysis in a fusion reactor. Therefore, the accurate quantification of fracture toughness of tungsten alloys is needed. However, due to the inherent brittleness of tungsten, it is difficult to introduce a sharp fatigue pre-crack needed for the fracture toughness test. In this study, a novel fatigue pre-cracking method was developed and applied to the small-sized disc-type compact tension (DCT) specimens of double-forged pure tungsten. To overcome the brittleness and poor oxidation resistance, a low-frequency tensile fatigue pre-cracking was performed at 600 °C in Ar environment, which resulted in the introduction of a sharp pre-crack to DCT specimens. Then, fracture toughness tests were conducted at room temperature (RT), 400 °C, and 700 °C in air and Ar gas environments using as-machined and pre-cracked DCT specimens. At RT and 400 °C, the test environment and crack tip radius did not affect the fracture toughness measurement. However, at 700 °C, the Ar gas environment and the presence of a sharp fatigue pre-crack resulted in a decrease in the measured fracture toughness. Thus, it was suggested that, for the conservative fracture toughness measurement of pure tungsten, fatigue pre-cracking and fracture toughness test should be performed in an inert environment, especially for high-temperature tests.

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Section: Fracture Toughness Test Resultsmentioning

confidence: 99%

Measurement of Fracture Toughness of Pure Tungsten Using a Small-Sized Compact Tension Specimen

et al. 2020

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“…The relationship between S i j and b i / W for different reference uncracked ligament length b i / W of SEB specimen for Q345B is shown in Figure . By referring to the work of Bao et al, the exponent m of geometry function in Equation can be easily determined by fitting the curve of S i j versus b i / W with a power function. This property can also be observed in the CT specimen, and the details are not repeated.…”

Section: Resultsmentioning

confidence: 99%

A method to evaluate ductile fracture toughness based on load separation principle

Bao

Liu

et al. 2018

Fatigue Fract Eng Mat Struct

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In combination with load separation principle, the P‐V curves of blunt‐notched specimens with different stationary cracks can be explicitly expressed as a unified formula. Further, a load separation‐based direct calibration (LSDC) method to predict instantaneous crack size and J‐resistance curve of growing cracked specimen has been developed. Two specimen configurations, compact tension and single edge‐notched bending, which are made of Cr2Ni2MoV and Q345B, respectively, are employed to verify the validity of LSDC method. The results show that the estimated J‐resistance curves are more reasonable in comparison with those obtained by unloading compliance and normalization method.

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“…Landes and Begley 39 proposed that σ YS is used to calculate the length of stretch zone and 2σ Y was chosen as the slope of blunting line. In ASTM E1820 and many other literatures, 14,[26][27][28][29][30] σ Y is used for determining the blunted crack advance Δa bi . As stated in Landes and Begley, 39 the purpose of the blunting line is to determine fracture toughness, J Ic , not the blunting corrected crack length a bi .…”

Section: The Modified Nmmentioning

confidence: 99%

“…The performance in terms of accuracy of the NM for a range of steels has been investigated by various researchers with different specimen materials. [26][27][28][29][30][31][32][33] They used UC as the benchmark to evaluate the performance of NM because UC is popular and usually assumed to be reliable. Their test results show that a large difference exists in fracture toughness as determined by UC and NM.…”

Section: Introductionmentioning

confidence: 99%

“…An examination of test results in these references [26][27][28][29][30][31][32][33] shows that the degree of difference in fracture toughness depends on the mechanical properties of the tested materials. For SUS 316L steel, A285 carbon steel and THS steel, the J-R curves and fracture toughness determined by the NM, the UC method, and the electric potential method are almost identical.…”

Section: Introductionmentioning

confidence: 99%

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A modified normalization method for determining fracture toughness of steel

Gao

Wang

et al. 2020

Fatigue Fract Eng Mat Struct

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Normalization method (NM) is a practical method for determining the J–R curves and fracture toughness of steels. There is some concern, however, about the performance of this method on steels with small strain hardening exponent and yield strength owing mainly to the assumption of infinite strain hardening exponent. This paper intends to analytically modify the NM by removing this assumption and incorporating the strain hardening in calculating the blunting corrected crack length. This modification enables the NM to be applied to steels with small strain hardening exponent and yield strength. Experiments are undertaken to verify the modified NM (CNM). A comparison of fracture toughness determined by CNM with that by the unloading compliance method and NM corroborates the improved accuracy of the developed CNM. The paper concludes that the developed CNM overcomes the deficiency of the NM for steels with small strain hardening exponent and yield strength.

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Improved normalization method for ductile fracture toughness determination based on dimensionless load separation principle

Cited by 14 publications

References 15 publications

Measurement of Fracture Toughness of Pure Tungsten Using a Small-Sized Compact Tension Specimen

Measurement of Fracture Toughness of Pure Tungsten Using a Small-Sized Compact Tension Specimen

A method to evaluate ductile fracture toughness based on load separation principle

A modified normalization method for determining fracture toughness of steel

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