Relationship between fracture toughness and crack extension resistance curves (R curves) for Ti-6Al-4V alloys

1998 ◽  
Vol 29 (3) ◽  
pp. 781-789 ◽  
Author(s):  
Takao Horiya ◽  
Teruo Kishi
Keyword(s):  
Fracture Toughness ◽  
Crack Extension ◽  
Resistance Curves

The Relationship of the Resistance Curve and Gc to Specimen Configuration

1977 ◽  
Vol 28 (1) ◽  
pp. 28-38 ◽  
Author(s):  
N J I Adams ◽  
H G Munro
Keyword(s):  
Fracture Toughness ◽  
Plastic Zone ◽  
Aluminium Alloys ◽  
Crack Extension ◽  
Thin Sheet ◽  
Compact Tension ◽  
Resistance Curve ◽  
Resistance Curves ◽  
Relationship Of ◽  
The Relationship

SummaryFollowing a brief introduction, an examination is presented of the factors which define fracture toughness, resistance-curve relationships and the extent of stable crack extension in thin-sheet failure. Tests have been performed on three aluminium alloys to establish the variations in the shape of resistance curves, using both compliance-indicated and measured absolute values of crack length in compact tension specimens and centre crack sheets. The results show that both the toughness and the resistance curves of the two specimen types are different and that these differences cannot be explained wholly by consideration of crack tip plastic zone sizes.

Estimation of Fracture Toughness JIC by Miniature Specimen Hydraulic Bulge Test

2017 ◽  
Vol 898 ◽  
pp. 753-757
Author(s):  
Le Le Gui ◽  
Tong Xu ◽  
Bin An Shou ◽  
Han Kui Wang ◽  
Jing Xiang
Keyword(s):  
Fracture Toughness ◽  
Fracture Energy ◽  
Fracture Strain ◽  
Bulge Test ◽  
Miniature Specimen ◽  
Hydraulic Bulge Test ◽  
Hydraulic Bulge ◽  
Resistance Curves ◽  
Miniature Specimens ◽  
Load Deflection Curve

The fracture toughness tests and a new miniature specimen technology named hydraulic bulge test (HBT) of 3Cr1Mo1/4V at four service time were carried out. Four J-R resistance curves by single-specimen method with one inch CT specimens were obtained to compute the JIC. Different definitions of equivalent fracture strain according to the section morphologies of HBT testing specimens were compared, and fracture energy of miniature specimens with three different thicknesses (0.4mm, 0.5mm and 0.6mm) were also calculated. Results showed that the typical HBT load-deflection curve can be divided into four sections like SPT curve. Equivalent fracture strain and fracture energy EHB can be chosen as two fracture parameters for the HBT specimen. Ductile fracture toughness JIC can be related approximately linearly to both the equivalent fracture strain and fracture energy EHB.

Determination of Fracture Toughness and K-R Curve for 2524-T3 Aluminum Alloy

2011 ◽  
Vol 291-294 ◽  
pp. 1039-1042
Author(s):  
Wei Xie ◽  
Shao Wei Tu ◽  
Qi Qing Huang ◽  
Ya Zhi Li
Keyword(s):  
Fracture Toughness ◽  
Aluminum Alloy ◽  
Stress Fracture ◽  
Test Data ◽  
Plane Stress ◽  
Crack Extension ◽  
Room Temperature ◽  
Mode I ◽  
Average Value

In the present work, the resistance to crack extension of 2524-T3 aluminum alloy under Mode I loading was studied by using the middle-cracked tension M (T) specimens. The curve, plane-stress fracture toughness and apparent plane-stress fracture toughness were calculated by test data. The average value of measured fracture toughness at room temperature was 161 MPam1/2. The results and conclusions can be referred in airplane skin design.

scholarly journals Evaluation of ductile tearing for API-5L X70 pipeline grade steel using SENT specimens

2015 ◽  
Vol 6 (3) ◽  
pp. 8
Author(s):  
Nicholas Ohms ◽  
Diego Belato Rosado ◽  
Wim De Waele
Keyword(s):  
Crack Growth ◽  
Crack Extension ◽  
Crack Growth Resistance ◽  
Fracture Surfaces ◽  
Edge Notch ◽  
Resistance Curves ◽  
Unloading Compliance ◽  
Inner Diameter ◽  
Tearing Resistance ◽  
Hardness Map

Pipelines in harsh environments may be subjected to large deformations. Classic stress-based design needs to be complemented with strain-based design. An important parameter in the design is the crack growth resistance. SENT testing (Single Edge Notch Tension) allows to determine the so-called material’s tearing resistance curve. Very recently the first standard on SENT testing, BS 8571:2014, has been published. SENT testing is however still subject to extensive research and different approaches with respect to eg. notch placement, crack extension measurement and analysis exist. In this paper two methods for calculating crack extension based on the unloading compliance procedure are used and compared, proving that they show little difference. This is performed on an API-5L X70 steel grade and this for different configurations, namely an inner diameter notch and a through thickness notch. The results showed little difference between the different configurations, although the inner diameter showed higher crack growth resistance. Furthermore, the results are compared to visual observations of the fracture surfaces and a hardness map. The fracture surfaces corresponded to the obtained resistance curves. However, no real correlation between the hardness map and the other results could be seen.

Further Extension of the Unloading Compliance Method to Measure J-R Curves Based on CMOD Data

2008 ◽  
Author(s):  
Sebastian Cravero ◽  
Claudio Ruggieri
Keyword(s):  
Fracture Toughness ◽  
Crack Growth ◽  
Test Procedure ◽  
Crack Mouth Opening Displacement ◽  
Evaluation Procedure ◽  
Test Technique ◽  
Resistance Curves ◽  
Unloading Compliance ◽  
Resistance Data ◽  
Unloading Compliance Method

Laboratory testing of fracture specimens to measure resistance curves (J-Δa) have focused primarily on the unloading compliance method using a single specimen. Current estimation procedures (which form the basis of ASTM 1820 standard) employ load line displacement (LLD) records to measure fracture toughness resistance data incorporating a crack growth correction for J. An alternative method which potentially simplifies the test procedure involves the use of crack mouth opening displacement (CMOD) to determine both crack growth and J. This study provides further developments of the evaluation procedure for J in cracked bodies that experience ductile crack growth based upon the eta-method and CMOD data. The methodology broadens the applicability of current standards adopting the unloading compliance technique in laboratory measurements of fracture toughness resistance data (J resistance curves). The developed J evaluation formulation for growing cracks based on CMOD data provides a viable and yet simpler test technique to measure crack growth resistance data for ductile materials.

scholarly journals Experimental conditions affecting the measured fracture toughness at the microscale: Notch geometry and crack extension measurement

2020 ◽  
Vol 191 ◽  
pp. 108582 ◽  
Author(s):  
Ashish Kumar Saxena ◽  
Steffen Brinckmann ◽  
Bernhard Völker ◽  
Gerhard Dehm ◽  
Christoph Kirchlechner
Keyword(s):  
Fracture Toughness ◽  
Crack Extension ◽  
Experimental Conditions ◽  
Notch Geometry

The Development of a Surface Crack in a Thick Vessel Under Ductile Tearing

2009 ◽  
Author(s):  
Osama Terfas ◽  
Bostjan Bezensek
Keyword(s):  
Crack Extension ◽  
Driving Forces ◽  
Ductile Crack ◽  
Ductile Tearing ◽  
Surface Flaws ◽  
Resistance Curves ◽  
The Mean ◽  
Surface Breaking Crack ◽  
Tearing Resistance ◽  
Leak Before Break

The development of the shape and size of a flaw in a pressure vessel is important in fitness-for-service evaluations such as leak-before-break. In this work finite element modelling is used to evaluate the mean stresses and the J-integral around a front of a surface-breaking flaw. These results show non-uniform constraint levels and crack driving forces around the crack front at large deformation levels, which contrast those at low deformation levels. A new procedure is developed to estimate the amount of ductile crack extension around a surface-breaking crack on the basis of ductile tearing resistance curves of deep and shallow cracked fracture mechanics samples. The procedure is applied to surface flaws to simulate ductile crack extension under ductile tearing and show the evolution of the initial flaw shape. Results show that both, initially semi-circular and initially semi-elliptical flaws develop towards the same shape in bending.

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