Comparison of J-Integral Values and J-R Curves Between Carbon Steel Compact Tension Specimen and Pipe Specimen

2004 ◽  
Author(s):  
Masahiro Takanashi ◽  
Satoshi Izumi ◽  
Shinsuke Sakai ◽  
Naoki Miura
Keyword(s):  
Fracture Toughness ◽  
Carbon Steel ◽  
Crack Initiation ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
Small Scale ◽  
Outer Diameter ◽  
J Integral ◽  
Tension Specimen ◽  
Elastic Plastic

In the present study, the transferability of elastic-plastic fracture toughness from a small-scale to a large-scale specimen was experimentally confirmed for carbon steel pipe with mild toughness. Fracture toughness tests were carried out on a pipe specimen 318.5 mm in outer diameter, 10.3 mm in thickness and having a through-wall crack, and also on a compact tension specimen 9.7mm in thickness, 25.4 mm in width, that had been cut out from the pipe specimen. Test results indicated the J-integral value of the pipe specimen at the crack initiation to be nearly twice that of the CT specimen. Finite element analysis conducted on the two specimens indicated this difference to arise primarily from the constraint near the crack front. Discussion was also made of the effects of crack orientation on elastic-plastic fracture toughness of CT specimens. The J-integral value at crack initiation in the specimen whose crack direction coincided with the pipe axial was found to be almost 54 % more than for specimens whose crack direction was circumferential.

Influence of Sulfur Content on the Fracture Toughness Properties of 2 1/4 Percent Cr-1 Percent Mo Steel

1976 ◽  
Vol 98 (2) ◽  
pp. 135-142 ◽  
Author(s):  
J. F. Copeland
Keyword(s):  
Fracture Toughness ◽  
Sulfur Content ◽  
Detrimental Effect ◽  
Crack Opening ◽  
Analytical Techniques ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
Tension Specimen ◽  
Microvoid Coalescence ◽  
Opening Displacement

The effects of sulfur content on the fracture toughness properties of 2 1/4Cr-1 Mo steel were evaluated at test temperatures above, at, and below the nil ductility transition temperature (NDTT) of −23°C (−10°F). Small, 12.7-mm (0.5-in.) thick compact tension specimen results were combined with J-integral, Equivalent Energy, and Crack Opening Displacement analytical techniques to provide KIc results up to 22°C (72°F). It was found that the sulfur content of this steel has a large detrimental effect on KIc at the NDTT and above, where microvoid coalescence is the fracture mode. Sulfur has no significant effect at −73°C (−100°F) where cleavage occurs. These results also indicate that the higher Charpy V-notch energy at NDTT, shown by lower sulfur steels, is translatable into increased fracture resistance.

Experimental evaluation of fracture properties of bovine hip cortical bone using elastic–plastic fracture mechanics

2021 ◽  
pp. 1-10
Author(s):  
Waseem Ur Rahman ◽  
Rafiullah khan ◽  
Noor Rahman ◽  
Ziyad Awadh Alrowaili ◽  
Baseerat Bibi ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Plastic Deformation ◽  
Fracture Mechanics ◽  
Cortical Bone ◽  
Elastic Deformation ◽  
Compact Tension ◽  
J Integral ◽  
Elastic Plastic ◽  
American Society ◽  
Fracture Specimens

BACKGROUND: Understanding the fracture mechanics of bone is very important in both the medical and bioengineering field. Bone is a hierarchical natural composite material of nanoscale collagen fibers and inorganic material. OBJECTIVE: This study investigates and presents the fracture toughness of bovine cortical bone by using elastic plastic fracture mechanics. METHODS: The J-integral was used as a parameter to calculate the energies utilized in both elastic deformation (Jel) and plastic deformation (Jpl) of the hipbone fracture. Twenty four different types of specimens, i.e. longitudinal compact tension (CT) specimens, transverse CT specimens, and also rectangular unnotched specimens for tension in longitudinal and transverse orientation, were cut from the bovine hip bone of the middle diaphysis. All CT specimens were prepared according to the American Society for Testing and Materials (ASTM) E1820 standard and were tested at room temperature. RESULTS: The results showed that the average total J-integral in transverse CT fracture specimens is 26% greater than that of longitudinal CT fracture specimens. For longitudinal-fractured and transverse-fractured cortical specimens, the energy used in the elastic deformation was found to be 2.8–3 times less than the energy used in the plastic deformation. CONCLUSION: The findings indicate that the overall fracture toughness measured using the J-integral is significantly higher than the toughness calculated by the stress intensity factor. Therefore, J-integral should be employ to compute the fracture toughness of cortical bone.

scholarly journals A Simple Method for Theoretical Prediction of Fracture Toughness of Multilayered Composites

2003 ◽  
Vol 12 (4) ◽  
pp. 096369350301200 ◽  
Author(s):  
R. Ramesh Kumar ◽  
P.N. Dileep ◽  
S. Renjith ◽  
G. Venkateswara Rao
Keyword(s):  
Fracture Toughness ◽  
Crack Initiation ◽  
Theoretical Prediction ◽  
Test Data ◽  
Fibre Orientation ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
Initial Crack ◽  
Simple Method ◽  
Multilayered Composites

Intralaminar fracture toughness of a fibre-reinforced angle ply and cross ply laminates are generally obtained by testing compact tension specimen and theoretically predicted using the well-known MCCI approach. The crack initiation direction, which is treated as a branch direction for the theoretical prediction, is an apriori. A conservative estimation on the toughness value obtained by considering branch crack angle corresponding to each fibre orientation in a laminate shows a gross error with respect to test data. In the present study a new criterion for the prediction of crack initiation angle is arrived at based on Tsai-Hill minimum strain energy density criterion. This shows a very good agreement with test data available in literature on fracture toughness of various multilayered composites with large size cracks with a/w ≥ 0.3. It is interesting to note that in a multilayered composite a simple method of prediction in which crack initiation direction is assumed to be the fibre orientation that is close to the initial crack direction gives a good estimation of the intralaminar fracture toughness.

C-Specimen Fracture Toughness Testing: Effect of Side Grooves and η Factor

2003 ◽  
Author(s):  
Y. Kim ◽  
Y. J. Chao ◽  
M. J. Pechersky ◽  
M. J. Morgan
Keyword(s):  
Fracture Toughness ◽  
Plane Strain ◽  
Crack Front ◽  
Testing Effect ◽  
Three Dimensional ◽  
Strain Analysis ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
J Integral ◽  
Η Factor

Elastic-plastic crack front fields in arc-shaped tension specimens (C-specimens) were analyzed by a three-dimensional finite element method. The effect of side grooves on the ductile fracture behavior was investigated by studying the J-integral distribution, plane-strain constraint parameter, and development of plastic zones and comparing to experimental data. The applicability of the η factor (derived for use with compact tension specimens) for the calculation of J-integral values for the C-specimen was also investigated. The results show that side grooves promote and establish near plane strain conditions at the crack front in sub-size specimens. It was also found that a two-dimensional plane-strain analysis in conjunction with the standard American Society for Testing and Materials (ASTM) tests was sufficient to determine the fracture toughness values from side-grooved C-specimen. The results indicate the η factor for compact tension specimen as specified in the ASTM standards appears to produce reliable results for the calculation of J of C-specimens.

C-Specimen Fracture Toughness Testing: Effect of Side Grooves and η Factor

2004 ◽  
Vol 126 (3) ◽  
pp. 293-299 ◽  
Author(s):  
Y. Kim ◽  
Y. J. Chao ◽  
M. J. Pechersky ◽  
M. J. Morgan
Keyword(s):  
Fracture Toughness ◽  
Plane Strain ◽  
Crack Front ◽  
Testing Effect ◽  
Three Dimensional ◽  
Strain Analysis ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
J Integral ◽  
Η Factor

Elastic-plastic crack front fields in arc-shaped tension specimens (C-specimens) were analyzed by a three-dimensional finite element method. The effect of side grooves on the ductile fracture behavior was investigated by studying the J-integral distribution, plane-strain constraint parameter, and development of plastic zones and comparing to experimental data. The applicability of the η factor (derived for use with compact tension specimens) for the calculation of J-integral values for the C-specimen was also investigated. The results show that side grooves promote and establish near plane strain conditions at the crack front in sub-size specimens. It was also found that a two-dimensional plane-strain analysis in conjunction with the standard American Society for Testing and Materials (ASTM) tests was sufficient to determine the fracture toughness values from side-grooved C-specimen. The results indicate the η factor for compact tension specimen as specified in the ASTM standards appears to produce reliable results for the calculation of J of C-specimens.

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