Fracture Toughness Determinations of A-302B and Ni-Mo-V Steels With Various Size Specimens

1966 ◽  
Vol 88 (4) ◽  
pp. 783-791 ◽  
Author(s):  
D. F. Mowbray ◽  
A. J. Brothers ◽  
S. Yukawa
Keyword(s):  
Fracture Toughness ◽  
Crack Opening ◽  
Bend Angle ◽  
Opening Displacement ◽  
Fatigue Precrack ◽  
Strain Fracture ◽  
Shear Lip ◽  
Angle Crack ◽  
Fracture Tests ◽  
Increasing Temperature

Fracture tests were conducted on three steels obtained from heavy-section pieces over a range of test temperatures using single-edge notched (SEN) specimens under tensile loading and notched-bar (NB) specimens in bending. The SEN tests were performed on specimens 0.125 and 0.4 in. thick plus a few specimens 0.020 in. thick. In the NB series Charpy-sized specimens (0.4 in. square) were tested at various temperatures with additional tests on smaller and larger specimens up to 6 in. square at selected temperatures. All specimens were provided with a fatigue precrack at the tip of the notch. The tests were conducted to determine the capability of various size specimens for providing valid plane-strain fracture toughness (GIc or KIc) values at various temperatures for these steels. At very low temperatures all specimens gave similar KIc values. With increasing temperature, KIc values obtained from the larger specimens remained relatively constant and then increased rapidly. At higher temperatures within this range, valid KIc values could not be measured with small specimens. Two possible methods of estimating KIc at these temperatures from small specimen data are discussed. One of these involves a correlation between fracture toughness and shear-lip thickness. The second makes use of a relation between bend angle, crack-opening-displacement, and fracture toughness. The test results are analyzed to show that both methods can be very useful.

scholarly journals Toughness Calculation of Postfire Normal Concrete

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Qingyang Chen ◽  
Anjing Tang ◽  
Zhoudao Lu
Keyword(s):  
Fracture Toughness ◽  
Critical Load ◽  
Crack Opening Displacement ◽  
Analytical Method ◽  
Crack Opening ◽  
Fracture Model ◽  
Opening Displacement ◽  
Normal Concrete ◽  
Critical Fracture ◽  
Fracture Tests

Fracture tests of postfire normal concrete with ten temperatures up to 600°C are implemented. Residual fracture toughness using analytical method is determined. Two situations are divided at critical load when calculating the cohesive fracture toughness. The initial and critical fracture toughness could be calculated from the complete load-crack opening displacement curves. Finally, the validation of double-Kfracture model to the postfire concrete specimens is proved.

Fracture Tests Of Polysilicon Film

1997 ◽  
Vol 505 ◽  
Author(s):  
W. N. Sharpe ◽  
B. Yuan ◽  
R. L. Edwards
Keyword(s):  
Thin Films ◽  
Fracture Toughness ◽  
Crack Opening Displacement ◽  
Crack Opening ◽  
Tensile Loading ◽  
Opening Displacement ◽  
Polysilicon Film ◽  
Fracture Tests

ABSTRACTA new test approach is presented to measure the fracture toughness of thin films. The polysilicon specimen is a center-cracked panel that is 3.5 μm thick and 3 mm wide with a 100 μm long slot in the center. It is subjected to tensile loading, and the crack-opening displacement is measured by interferometry. The average toughness is 1.4 ± 0.65 MPa-m1/2.

Experimental methods for fracture toughness measurement

1975 ◽  
Vol 10 (4) ◽  
pp. 225-232 ◽  
Author(s):  
A H Priest
Keyword(s):  
Fracture Toughness ◽  
Crack Opening ◽  
Plane Strain Fracture Toughness ◽  
Opening Displacement ◽  
Testing Procedures ◽  
Monitoring Technique ◽  
Fracture Toughness Measurement ◽  
Strain Fracture ◽  
Crack Monitoring ◽  
Toughness Measurement

Recommended methods for measuring fracture toughness parameters are discussed. The relevant Draft British Standards are: (a) Draft for Development 3:1971 ‘Methods for Plane Strain Fracture Toughness ( KI c) Testing’. (b) Draft for Development 19:1972 ‘Methods for Crack Opening Displacement (COD) Testing’. These documents are being revized and updated for publishing as full British Standards and any significant additions and alterations are noted. The situation with respect to non-standard tests is reviewed. The fracture toughness parameters under this heading include JI c, equivalent energy values, fracture propagation energy values and R-curve analysis. Particular attention is paid to the influence of strain rate on testing procedures and a crack monitoring technique is discussed.

Evaluation of Wedge Splitting Fracture Tests Using the Double-K Model: Analysis of the Effect of Hemp Fibre Dosage and Length in Concrete Specimens

2016 ◽  
Vol 249 ◽  
pp. 142-146
Author(s):  
Hana Šimonová ◽  
Ivana Havlíková ◽  
Jakub Sobek ◽  
Alaa Abdulrahman ◽  
Zbyněk Keršner ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Crack Propagation ◽  
Crack Opening Displacement ◽  
Crack Opening ◽  
Opening Displacement ◽  
Critical Crack ◽  
Hemp Fibre ◽  
Fracture Tests ◽  
Critical Crack Opening ◽  
Wedge Splitting

This paper deals with the results obtained from the employment of a selected fracture model to evaluate wedge splitting fracture tests carried out on hemp fibre concrete specimens. The research work was focused mainly on the effect of the dosage and length of hemp fibres on the initiation part of crack propagation in concrete specimens, and on critical crack opening displacement. Concrete mixtures with different volumetric dosages (0.5, 1.0 and 2.0 %) and fibre lengths (10, 20 and 40 mm) were prepared, and six identical specimens were cast from each mixture. Specimens were also cast from a reference mixture, which was without fibres. The specimens were provided with an initial notch and tested using the wedge splitting test method. Load versus crack mouth opening displacement diagrams were recorded during testing and (after data filtering and appropriate modifications) subsequently evaluated using the Double-K fracture model. This model allows the evaluation of two material parameters – the initiation fracture toughness, which defines the onset of stable crack propagation, and the unstable fracture toughness, which defines the onset of unstable cracking or failure. Finally, the critical crack opening displacement was determined with the assumption of the bilinear function of softening in tension.

The Fracture Toughness of Hardened Tool Steels

1987 ◽  
Vol 109 (4) ◽  
pp. 314-318 ◽  
Author(s):  
D. F. Watt ◽  
Pamela Nadin ◽  
S. B. Biner
Keyword(s):  
Fracture Toughness ◽  
Crack Growth ◽  
Slow Crack Growth ◽  
Crack Opening ◽  
Compact Tension ◽  
Testing Procedure ◽  
Tool Steels ◽  
Opening Displacement ◽  
Tempering Temperature ◽  
Toughness Testing

This report details the development of a three-stage fracture toughness testing procedure used to study the effect of tempering temperature on toughness in 01 tool steel. Modified compact tension specimens were used in which the fatigue precracking stage in the ASTM E-399 Procedure was replaced by stable precracking, followed by a slow crack growth. The specimen geometry has been designed to provide a region where slow crack growth can be achieved in brittle materials. Three parameters, load, crack opening displacement, and time have been monitored during the testing procedure and a combination of heat tinting and a compliance equation have been used to identify the position of the crack front. Significant KIC results have been obtained using a modified ASTM fracture toughness equation. An inverse relationship between KIC and hardness has been measured.

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.

Mode Mixity in the Fracture Toughness Evaluation of Heat-Affected-Zone Material Using SEN(T) Experiment

2021 ◽  
Author(s):  
Sureshkumar Kalyanam ◽  
Yunior Hioe ◽  
Gery Wilkowski
Keyword(s):  
Fracture Toughness ◽  
Crack Growth ◽  
Heat Affected Zone ◽  
Crack Opening ◽  
Growth Direction ◽  
Mode I ◽  
Mode Ii ◽  
Mode Mixity ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement

Abstract SEN(T) specimens provide good similitude for surface cracks (SC) in pipes, where a SC structure has lower constraint condition than typically used fracture toughness specimens such as SEN(B) , and C(T). Additionally, the SENT specimen eliminates concern of material anisotropy since the crack growth direction in the SENT is the same as in a surface-cracked pipe. While the existing recommended and industrial practices for SEN(T) have been developed based on assumption of homogenous or mono-material across the crack, their applicability for the evaluation of fracture toughness of heat-affected-zone (HAZ) were evaluated in this investigation. When conducting tests on SEN(T) specimens with prescribed notch/crack in the HAZ, the asymmetric deformation around the crack causes the occurrence of a combination of Mode-I (crack opening) and Mode-II (crack in-plane shearing) behavior. This mode mixity affects the measurement of the crack-tip-opening-displacement (CTOD) and evaluation of elastic-plastic fracture mechanics parameter, J. The CTOD-R curve depicts the change in toughness with crack growth, in a manner similar to the J-R curve methodology. The experimental observations of Mode-I and Mode-II behavior seen in tests of SEN(T) specimens with notch/crack in the HAZ and as the crack propagates through the weld/HAZ thickness were investigated. The issues related to and the changes needed to account for such behavior for the development of recommended practices or standards for SEN(T) testing of weld/HAZ are addressed.

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