Back-Face Strain Compliance and Electrical-Potential Crack Length Calibrations for the Disk-Shaped Compact-Tension DC(T) Specimen

1994 ◽  
Vol 22 (2) ◽  
pp. 117 ◽  
Author(s):  
DR Petersen ◽  
CJ Gilbert ◽  
JM McNaney ◽  
RH Dauskardt ◽  
RO Ritchie
Keyword(s):  
Crack Length ◽  
Electrical Potential ◽  
Compact Tension ◽  
Back Face

Improved Elastic Compliance Equation and its Inverse Solution for Compact Tension Specimens

2017 ◽  
Author(s):  
Xian-Kui Zhu
Keyword(s):  
Crack Length ◽  
Maximum Error ◽  
Compact Tension ◽  
Crack Size ◽  
Accurate Solution ◽  
Elastic Compliance ◽  
Load Line Displacement ◽  
Standard Specimens ◽  
Specimen Test ◽  
Toughness Testing

ASTM E1820 is a well-developed fracture test standard and has been used worldwide for fracture toughness testing on ductile materials in terms of the J-integral or J-R curve. This standard recommends the elastic unloading compliance technique for measuring crack length in a single specimen test, and an accurate elastic compliance equation is needed to estimate physical crack length. Compact tension (CT) specimen is one of the most often used standard specimens with crack length ratios of 0.45≤a/W≤0.70 prescribed in E1820 for J-R curve testing. The stress intensity factor K of CT specimens used in E1820 was developed by Srawley (IJF, 1976) and has been commonly accepted as the most accurate solution. The compliance equation of CT specimens was developed by Saxena and Hudak (IJF, 1978) and has been used in ASTM E1820 for decades. However, recent results showed that the load-line displacement (LLD) compliance equation is not consistent with that determined from its K solution, and the maximum error of LLD compliance can be larger than 7% at a/W = 0.32 and ∼ 5% at a/W = 0.45 (E1820 standard crack size). The FEA results confirmed that the K solution in E1820 is indeed very accurate, but its compliance equation is less accurate. Thus, an improved compliance equation with high accuracy is developed from the accurate K solution using the numerical integration technique and shooting method.

Prediction of Fatigue Crack Growth of 2024-T351 by Grey GM(1,1) Model with Rolling Check

2013 ◽  
Vol 690-693 ◽  
pp. 1779-1783 ◽  
Author(s):  
Chih Chung Ni
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Length ◽  
Crack Growth ◽  
Compact Tension ◽  
Growth Data ◽  
Alloy Plate ◽  
Loading Cycle ◽  
Crack Growth Curve ◽  
Accuracy Of Prediction

The study is focused on the investigations into applying the grey model with rolling check to the prediction of fatigue crack growth. Fatigue crack growth data of compact tension specimens made of 2024-T351 aluminum-alloy plate tested under constant-amplitude loads were carried out for verifications. The optimal values of parameter affecting the accuracy of prediction were found by variational analysis. Using four experimental crack lengths as the source series and the optimal value of parameter for modelling with rolling check, it was found almost entire fatigue crack growth curve of the specimen can be predicted accurately. Besides, the analyzed results including number of rolling check performed, loading cycle corresponding to the maximum predicted crack length, fractured cycle of specimen, cycle ratio of loading cycle and fractured cycle, and percentage of error between maximum predicted and experimental crack length for all specimens were tabulated.

Additional Data Concerning French PWR RPV Steel to Evaluate the Relevance of a Size Effect Correction on Toughness in the Ductile-to-Brittle Transition

2014 ◽  
Author(s):  
C. Jacquemoud ◽  
I. Delvallée-Nunio ◽  
M. Nédélec ◽  
F. Balestreri
Keyword(s):  
Fracture Toughness ◽  
Size Effect ◽  
Crack Length ◽  
Compact Tension ◽  
Ferritic Steels ◽  
Transition Range ◽  
Brittle Transition ◽  
Reference Length ◽  
Rpv Steel ◽  
Ductile To Brittle Transition

In the ductile-to-brittle transition range of ferritic steels, fracture toughness exhibits a size effect. Up to now, in the safety demonstration of the French Reactor Pressure Vessel (RPV) integrity, a size effect correction has been considered by the operator to take into account fracture toughness variation of ferritic steels with crack length. The correction consists in increasing the toughness estimated on the RCC-M curve by a factor which depends on a reference length and on the crack length considered. IRSN has already examined the relevance of this correction through statistical analysis of toughness results coming from two ferritic steel databases. To complete its evaluation on French RPV steel, IRSN has supported a large experimental campaign on 16MND5 steel at different temperatures in the ductile-to-brittle transition (from −150°C to −50°C), including tests on various Compact Tension (CT) specimen geometries. Specimens with semi-elliptical crack have been also considered. The results confirm the observations made in its previous study: a size effect exists on mean or median toughness, for the latter more or less in accordance with Beremin theory. Nevertheless, the minimum toughness appears to be independent of the specimen geometry. This indicates that the use of a size effect correction on minimum toughness is not relevant.

Back Face Strain Calibration for Crack Length Measurements

1994 ◽  
Vol 22 (6) ◽  
pp. 512 ◽  
Author(s):  
DR Petersen ◽  
WJD Shaw ◽  
W Zhao
Keyword(s):  
Crack Length ◽  
Length Measurements ◽  
Back Face

Application of the Electrical Potential Method to Crack Length Measurements Using Johnson's Formula

1981 ◽  
Vol 9 (3) ◽  
pp. 218 ◽  
Author(s):  
KC Lieb ◽  
R Horstman ◽  
KA Peters ◽  
CF Enright ◽  
RL Meltzer ◽  
...  
Keyword(s):  
Crack Length ◽  
Electrical Potential ◽  
Potential Method ◽  
Length Measurements

On the Creep Fracture Toughness of 2¼Cr1Mo Steel

2005 ◽  
Vol 297-300 ◽  
pp. 1464-1469 ◽  
Author(s):  
Fu Zhen Xuan ◽  
Shan Tung Tu ◽  
Zheng Dong Wang ◽  
Jian Ming Gong
Keyword(s):  
Fracture Toughness ◽  
High Temperature ◽  
Material Parameter ◽  
Electrical Potential ◽  
Creep Crack Growth ◽  
Compact Tension ◽  
Creep Fracture ◽  
Defect Assessment ◽  
Lower Temperature ◽  
Conservative Result

To assess the failure risk of high temperature structures, it is essential to obtain the creep fracture toughness of materials. In the present paper, Creep crack growth (CCG) tests for 2¼Cr1Mo steel have been carried out by utilizing the side grooved compact tension (CT) specimen and direct current (DC) electrical potential technique. The material parameter of creep fracture toughness, c mat K , were obtained from analysis of 11 CCG tests at temperatures of 500 and 565oC. It has been found that for 2¼Cr1Mo steel c mat K decreases with increasing time and increases with elevating temperature. For this reason, the value of c mat K at lower temperature or longer service time can be used to extract a conservative result in the high temperature defect assessment where the accurate value of c mat K is unavailable. It is also validated from this test that the proposed formula by Ainsworth et al can be adopted in practice.

Influence of Specimen Type, Crack Length and Evaluation Method on Quasi-Static and Dynamic Fracture Toughness Properties

2009 ◽  
Author(s):  
Conrad Zurbuchen
Keyword(s):  
Fracture Toughness ◽  
Crack Length ◽  
Evaluation Method ◽  
Mechanical Test ◽  
Compact Tension ◽  
Dynamic Fracture Toughness ◽  
Test Results ◽  
Evaluation Standards ◽  
Specimen Type ◽  
Surveillance Specimens

This paper provides a comparison of the influence of specimen type (single edge bend (SE(B)) specimen vs. compact tension C(T) specimen), specimen dimensions (crack length ratio a/W, thickness B) and the effect of the loading rate on fracture toughness properties. In the lower ductile-brittle transition region the quasi-static Master Curve (MC) reference temperature T0 is evaluated according to ASTM E 1921-08ae1 and the dynamic MC T0 according to the Swiss guideline HSK-AN-425, which is compared with a modified ASTM E 1921-08ae1 approach. The ductile behaviour was evaluated by quasi-static JR curve testing in which the applicability of several evaluation standards are compared (ASTM E 1820-08, ISO 12135, ESIS-P2). Quasi-static and dynamic MC temperatures T0 deviate by up to 68 K. SE(B) specimens with shorter crack lengths (a/W = 0.3) than prescribed by ASTM E 1921 yield the same T0 as specimens with a/W = 0.5. Thus, such short crack surveillance specimens are also suitable for fracture mechanical assessments. SE(B) specimens of B = 0.4T (1T = 1 inch) up to 3.2T show comparable T0, proving the transferability of fracture mechanical test results of small surveillance specimens to heavy-walled RPV structures.

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