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.

Effect of Sintering Temperature on Microstructure and Properties of VС/Fe Composite

2012 ◽  
Vol 430-432 ◽  
pp. 978-983
Author(s):  
Guo Jun Zhang ◽  
Zhi Ping Sun ◽  
Li Yan Zou
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Sintering Temperature ◽  
Growth Trend ◽  
Flexure Strength ◽  
Microstructure And Properties ◽  
Whole Process ◽  
Relationship Of ◽  
The Relationship ◽  
Composite Samples

VC/Fe composite samples were fabricated by sintering at 1050, 1100 and 1150°C in vacuum. The microstructure and mechanical properties of samples were examined, and the relationship of structure and mechanical properties for VC/Fe composite sintered at different temperature were studied. The results show that fracture toughness, hardness and density is increasing obviously at 1050-1100°Cwith the increasing sintering temperature, but the growth trend increases slowly at 1100-1150°C; in whole process with temperature increased, Flexure strength heighten trend obviously. The microstructure of VC/Fe composite changed from particles piled up together to the microstructure particles closely, VC particles set gradually into Fe with temperature increased, and the gap reduced gradually.

Crack Initiation and Propagation in Static Loaded Fracture Mechanics Tests in Steels Containing Atomic Hydrogen

2020 ◽  
Author(s):  
Philippa L. Moore ◽  
Menno Hoekstra ◽  
Alex Pargeter
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Crack Initiation ◽  
Plastic Zone ◽  
Crack Growth ◽  
Crack Extension ◽  
Low Alloy Steels ◽  
Ductile Tearing ◽  
Initiation Fracture Toughness ◽  
Stable Tearing

Abstract Hydrogen is well known to have a detrimental influence on the ductility of low alloy steels, reducing the fracture toughness. Standard test methods to characterize fracture toughness of steels in terms of ductile tearing resistance curves have not been developed to account for any hydrogen-driven contribution to the crack extension, Δa. Simply plotting J or CTOD against Δa is not necessarily appropriate for defining the initiation fracture toughness for tests performed in a hydrogen-charging environment. This paper explores a method to further analyse experimental data collected during fracture toughness tests, which allows the contribution of plasticity (i.e. when blunting precedes ductile tearing) to be considered separately from the initiation of crack extension (which could be by stable tearing and/or by hydrogen-driven crack extension). The principle is based on the assumption that a crack growing by a hydrogen-driven mechanism in a quasi-static fracture mechanics test performed in environment may not be associated with significant ductility in the plastic zone (which would accompany crack growth by stable tearing). The analytical method presented in this paper compares the different points of deviation from linear behavior of the components of J, to isolate the effects of ductility within the plastic zone from pure crack extension. In this way, the point of crack initiation can be defined in order to determine the relevant initiation fracture toughness; whether by blunting and stable tearing, or by hydrogen-driven crack growth. This approach offers a screening method which is illustrated using examples of fracture mechanics specimens tested in environments of varying severity (air, seawater with cathodic protection, and sour service). This method can be used to identify the relevant definition of initiation fracture toughness while allowing for a combination of ductile tearing, hydrogen-driven crack extension, or both, to be present during the test.

scholarly journals Effect Range of the Material Constraint in Different Strength Mismatched Laboratory Specimens

2020 ◽  
Vol 10 (7) ◽  
pp. 2434 ◽  
Author(s):  
Yue Dai ◽  
Jie Yang ◽  
Haofeng Chen
Keyword(s):  
Crack Propagation ◽  
Fracture Resistance ◽  
Compact Tension ◽  
Propagation Path ◽  
Resistance Curve ◽  
Single Edge ◽  
Integrity Assessment ◽  
Scientific Support ◽  
Resistance Curves ◽  
Initial Cracks

Different strength mismatched laboratory specimens that contain the compact tension (CT), single edge-notched tensile (SENT), and central-cracked tension (CCT) specimens with various specimen geometries, loading configurations, and initial cracks were selected to investigate the effect range of the material constraint systematically. The results showed that the effect range of material constraint exists in all the strength mismatched specimens and structures. The numerical value of the effect range is influenced by the geometry constraint. The high geometry constraint reduces the effect range of material constraint. When a material is located outside the effect range of material constraint, the fracture resistance curves and crack propagation paths of the specimens and structures are no longer influenced by the mechanical properties of the material. In addition, an interaction exists between the geometry constraint and material constraint. The high geometry constraint strengthens the effect of material constraint, whereas the fracture resistance curve and crack propagation path are insensitive to the material constraint under the low geometry constraint. The results in this study may provide scientific support for the structure integrity assessment and the design of strength mismatched structures.

Fracture Toughness Analysis of the China RPV Steel with Miniaturized Specimen

2016 ◽  
Vol 850 ◽  
pp. 41-46 ◽  
Author(s):  
Yun Lin ◽  
Wen Yang ◽  
Zhen Feng Tong ◽  
Guang Sheng Ning
Keyword(s):  
Fracture Toughness ◽  
Nuclear Power ◽  
Master Curve ◽  
Initiation Site ◽  
Cleavage Crack ◽  
Test Technique ◽  
Rpv Steel ◽  
Specimen Test ◽  
Relationship Of ◽  
The Relationship

Reactor pressurized vessel (RPV), which determines the lifetime of the nuclear power plant (NPP), is mainly forged using A508-3 steel in China. In order to meet the requirement of the small specimen test technique in the nuclear application, the fracture toughness of A508-3 steel was tested under-100°C using 1/4 CT specimens, and analyzed using Master Curve according to ASTM E 1921. In this work, the relationship of the KIC and the distance between the cleavage crack initiation site and the front of the fatigue crack is studied, and the transition temperature T0 of A508-3 is-98.7 oC, which is quite close to the test temperature.

Effects of the Stress Concentration and Plane Stress on the Essential Work of Fracture (EWF) Method

2014 ◽  
Vol 1042 ◽  
pp. 32-37
Author(s):  
Chao Zhao ◽  
Xiong Chen ◽  
Chang Sheng Zhou ◽  
Hong Mei Wang
Keyword(s):  
Stress Concentration ◽  
Plane Stress ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
Uniaxial Tensile ◽  
Geometric Features ◽  
Double Edge ◽  
Double Base ◽  
Relationship Of ◽  
The Relationship

In this article, we used standard dumbbell specimen (SDS), compact tension specimen (CTS) and Double edge notched specimen (DENS) which made of materials of modified double-base propellant to do the uniaxial tensile experiments under different tensile rates. In comparison, three kinds of specimen whoes geometric features are similar with the specimen above but the thickness is smaller, were also used to get the relationship of force (F) and displacement (l). After analysis of these relationship, we confirmed that the plane stress and stress concentration influence the use of EWF method. The experimental results prove that the geometric features of the specimen which are proposed by B.cotterell and J.K.reddel are absolutely right. But for the thicker specimen used by GUAN GONG and other researchers, we can just know the trend is correct, and should do further research to know the influence which specimen’s geometric characteristics bring to experiment.

Determination of J Resistance Curves From CWP Specimens

2012 ◽  
Author(s):  
Fan Zhang ◽  
Honggang Zhou ◽  
Yong-Yi Wang ◽  
Ming Liu ◽  
Yaxin Song
Keyword(s):  
Fracture Toughness ◽  
Crack Growth ◽  
J Integral ◽  
Resistance Curve ◽  
Constraint Condition ◽  
Longitudinal Loading ◽  
Resistance Curves ◽  
Unloading Compliance ◽  
Girth Welds

A crack is highly constrained in traditional toughness tests, e.g., CVN and SE(B). However, a crack in the girth welds of pipelines under longitudinal loading is low constrained. Curved wide plate (CWP) test provides similar constraint condition as that of pipeline girth weld. CWP tests are being used recently for strain-based design. One of the desirable outcomes from those tests is fracture toughness resistance curves. The resistance curve consists of two components, the crack growth and the toughness measure, such as J-integral or CTOD. The paper describes the development of procedures for the determination of those two components. A normalized equation was developed to estimate the crack growth from the experimentally measured unloading compliance. The equation was verified by multiple FEA simulations with different pipe geometries and materials. The second set of equations was developed to evaluate the J-integral through an incremental frame based on the instantaneous crack growth and the load-CMOD record. The application of the resistance curve procedures was demonstrated through CWP tests of X80 and X100 welds.

Effect of Holding Time on Microstructure and Properties of VC/Fe Composite

2012 ◽  
Vol 723 ◽  
pp. 353-357
Author(s):  
Guo Jun Zhang ◽  
Zhi Ping Sun ◽  
Li Yan Zou
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Relative Density ◽  
Bending Strength ◽  
Holding Time ◽  
Microstructure And Properties ◽  
Microstructure And Mechanical Properties ◽  
Relationship Of ◽  
The Relationship ◽  
Better Than

The microstructure and mechanical properties of samples were examined, and the relationship of structure and mechanical properties for VC/Fe composite sintered at different holding time were studied. Holding time can influence the mechanical properties, with the holding time rising, when the holding time is 80 min, the hardness is Max, it’s 10.71 GPa, the enhancing range is 37.66%; The relative density changes slower from 60 to 100 min; when the holding time is 60 minutes, fracture toughness and bending strength of material is 16.17 MPa•m 1/2 and 1070 MPa, it’s better than before.

Sign in / Sign up

Export Citation Format

Share Document