Determination of Crack Tip Energy Dissipation and Elastic-Plastic Fracture Toughness Parameter with Ductile Crack Extension

1981 ◽  
Vol 9 (6) ◽  
pp. 324 ◽  
Author(s):  
R Horstman ◽  
KA Peters ◽  
BM Schindler ◽  
RL Meltzer ◽  
MB Vieth ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Energy Dissipation ◽  
Crack Extension ◽  
Crack Tip ◽  
Ductile Crack ◽  
Elastic Plastic ◽  
Toughness Parameter

Fracture Toughness of PVC/NBR Blends Evaluated by the J-Integral

1993 ◽  
Vol 66 (4) ◽  
pp. 634-645
Author(s):  
N. Nakajima ◽  
J. L. Liu
Keyword(s):  
Fracture Toughness ◽  
Energy Dissipation ◽  
Crack Initiation ◽  
Crack Tip ◽  
J Integral ◽  
Integral Methods ◽  
Locus Method ◽  
Two Phases ◽  
Fracture Processes

Abstract The effect of gel on the fracture toughness of four PVC/NBR (50/50) blends was characterized by two different J- integral methods. Three of these blends are compatible blends with 33% acrylonitrile in NBRs, and the fourth with 21% acrylonitrile content, is an incompatible blend. Two types of gel are involved in this study microgels and macrogels. The J-integral methods are (1) conventional method proposed by Bagley and Landes and (2) crack initiation locus method proposed by Kim and Joe. The same load-displacement curves are used in both methods. However, the latter eliminates the energy dissipation away from the crack tip in the determination of Jc, while the former does not. Both methods produced almost the same results indicating that the energy dissipation away from the crack tip is negligible in these samples. The fracture toughness of a macrogel-containing blend is much greater than that of a microgel-containing blend, which, in turn, is only slightly greater than that of a gel-free blend. This implies that the two gel-containing blends have different fracture processes. The incompatible blend has the lowest fracture toughness due to weak interaction at the boundaries of the two phases.

Ductile Crack Growth Resistance and Rotation Behavior of Miniature C(T) Specimen

2020 ◽  
Author(s):  
Tomoki Shinko ◽  
Masato Yamamoto
Keyword(s):  
Fracture Toughness ◽  
Size Effect ◽  
Crack Growth ◽  
Crack Extension ◽  
Crack Tip ◽  
Crack Growth Resistance ◽  
Specimen Size ◽  
Ductile Crack ◽  
Rotation Center ◽  
Ductile Crack Growth

Abstract A utilization of a miniature compact tension (Mini-C(T)) specimen is expected to enable effective use of limited remaining surveillance specimens for the structural integrity assessment of a Reactor Pressure Vessel (RPV). For developing a direct fracture toughness evaluation method using Mini-C(T) specimen in the upper-shelf temperature range as well as ductile-brittle transition temperature range, this study is aimed to experimentally characterize the Mini-C(T) specimen’s size effect on ductile crack growth resistance and interpolate its mechanism. Mini-C(T) specimen and 0.5T-C(T) specimen were prepared from a Japanese RPV steel SQV2A, and the ductile crack growth tests were conducted on them at room temperature. As a result, the crack growth resistance of Mini-C(T) and 0.5T-C(T) specimens are comparable if the crack extension Δa is less than 0.5 mm. On the other hand, if Δa exceeds 0.5 mm, the crack growth resistance of Mini-C(T) specimen becomes lower than that of 0.5T-C(T) specimen. The measurements of stretch zone width and depth support the fact that the fracture toughness for ductile crack initiation of Mini-C(T) specimen is lower than that of 0.5T-C(T) specimen. From the rotational (crack mouth opening) deformation of Mini-C(T) specimen was measured by simultaneously measuring load-line and front face displacements. The distance between the crack tip and the rotation center of Mini-C(T) specimen is smaller than that of 0.5T-C(T) specimen during the test. Furthermore, The plastic zone in front of the crack tip reaches the rotation center up to the crack extension of Δa = 0.3 mm on Mini-C(T) specimen, indicating that the mechanism of the specimen size effect of Mini-C(T) specimen is likely a plastic constraint due to the influence of the rotation center locating near the crack tip. This suggests that the specimen size effect of Mini-C(T) specimen on ductile crack growth resistance is expected to be corrected by considering an effect of the plastic constraint.

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.

The determination of fracture toughness for a porous elastic-plastic solid

1987 ◽  
Vol 33 (2) ◽  
pp. 111-124
Author(s):  
A. Jagota ◽  
C. Y. Hui ◽  
P. R. Dawson
Keyword(s):  
Fracture Toughness ◽  
Elastic Plastic

scholarly journals Experimental – Numerical Analysis of Stress State in Front of the Crack Tip of Modified and Unmodified G17CrMo5-5 Cast Steel by Rare Earth Metals in a Brittle-Ductile Transition Region

2016 ◽  
Vol 61 (2) ◽  
pp. 1175-1181
Author(s):  
I. Dzioba ◽  
R. Pala ◽  
J. Kasinska
Keyword(s):  
Fracture Toughness ◽  
Rare Earth ◽  
Stress State ◽  
Numerical Analysis ◽  
Crack Extension ◽  
Cast Steel ◽  
Rare Earth Metals ◽  
Initial Moment ◽  
Brittle Ductile Transition

Abstract In the paper presented experimental data and numerical analysis of stress distribution in front of the crack of two melts of low-alloy G17CrMo5-5 cast steel-modified (M) by rare earth metals and original, unmodified (UM) in the temperature range, according to the brittle-ductile transition region. Experimental tests include determination of the tensile properties and fracture toughness characteristics for the UM and M cast steel. Numerical analysis includes determination of stress distribution in front of the crack at the initial moment of the crack extension. In the numerical computations, experimentally tested specimens SEN(B) were modeled. The true stress-strain curves for the UM and M cast steel were used in the calculation. It was shown that the maximum of the opening stresses at the initial moment of the crack extension occurs in the axis of the specimens and reaches similar level of about 3.5σ0 for both UM and M cast steel. However, the length of the critical distance, measured for stress level equal 3σ0, is great for the M in comparison to the UM cast steel. Also was shown that the UM cast steel increased the level of the stress state triaxiality parameters that resulted in a decrease of fracture toughness.

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