Assessing the fracture toughness of structural steels by the critical crack opening method

1977 ◽  
Vol 9 (11) ◽  
pp. 1369-1372
Author(s):  
D. V. Lebedev ◽  
L. V. Popova ◽  
V. N. Zikeev
Keyword(s):  
Fracture Toughness ◽  
Crack Opening ◽  
Structural Steels ◽  
Critical Crack ◽  
Critical Crack Opening ◽  
Opening Method

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.

A New Methodology for Estimating Fracture Criterion of Thin Sheets

2009 ◽  
Vol 417-418 ◽  
pp. 305-308
Author(s):  
Kalyan Kumar Ray ◽  
Ashmita Patra ◽  
Debashish Bhattacharjee
Keyword(s):  
Fracture Toughness ◽  
Crack Opening ◽  
Specimen Thickness ◽  
Interstitial Free ◽  
Thin Sheets ◽  
If Steel ◽  
Opening Displacement ◽  
Critical Crack ◽  
Suggested Technique ◽  
Critical Crack Opening

A simple and reliable method has been proposed for determining fracture toughness of thin sheets. The principle of the method considers that critical crack opening displacement (c) corresponds to a specific amount of load drop during fracture toughness tests. The suggested technique yields c value for an interstitial free (IF) steel as 2.04 mm in excellent correspondence with an indirect estimate of 1.97 mm from the popular energy extrapolation technique. The magnitude of c for IF steel sheets is found to decrease with decreasing thickness in agreement with the expected variation of this criterion with specimen thickness in gross yielding fracture mechanics (GYFM) regime.

Test for Crack Opening Displacement of Steel Fiber Reinforced Concrete under Three-Point Bending

2010 ◽  
Vol 36 ◽  
pp. 157-161 ◽  
Author(s):  
Tin Gyi Zhang ◽  
Yuan Bao Leng ◽  
Dan Ying Gao
Keyword(s):  
Crack Opening Displacement ◽  
Crack Opening ◽  
Mouth Opening ◽  
Crack Tip ◽  
Crack Mouth Opening Displacement ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Critical Crack ◽  
Critical Crack Opening ◽  
Crack Tip Opening

Based on the principle of electrical measurement method, the clip gauge was made to measure the crack opening displacement (COD).Through the three-point bending test on the specimens of steel fiber reinforced high strength concrete (SFHSC), the effect of the fiber volume fraction (ρf) upon the critical crack opening displacement (the critical crack tip opening displacement and the critical crack mouth opening displacement) was studied. The result shows that the effect of ρf on mouth-tip ratio (the ratio of critical crack mouth opening displacement to critical crack tip opening displacement) can reflect its effect upon the critical crack opening displacement. According to the geometrical relationship between the initial crack length and the critical crack opening displacement，calculation method for the initial crack length was proposed. Based on the test result, the formula was established for calculating the critical crack tip opening displacement.

Finite Element Analysis of Brittle Cracking due to Single Grit Rotating Scratch

2003 ◽  
Vol 70 (1) ◽  
pp. 147-151 ◽  
Author(s):  
G. Subhash ◽  
W. Zhang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Crack Opening ◽  
Damage Zone ◽  
Depth Of Cut ◽  
Opening Displacement ◽  
Element Analysis ◽  
Critical Crack ◽  
Critical Crack Opening ◽  
Brittle Material Removal

Finite element analysis of single grit rotating scratch on brittle materials was conducted using an “elastic-plastic-cracking” (EPC) model. The brittle material removal mechanism was modeled based on a critical crack-opening displacement criterion. It was found that the tangential and normal force profiles as well as the damage morphology observed in scratch experiments were fully captured by the EPC model. The results revealed that the induced damage zone size increases linearly with a brittleness parameter EY/σf21/3 as well as the maximum depth of cut.

scholarly journals Fracture toughness and crack growth of brackish ice using chevron-notched specimens

1994 ◽  
Vol 40 (135) ◽  
pp. 415-426
Author(s):  
Lars Stehn
Keyword(s):  
Fracture Toughness ◽  
Crack Growth ◽  
Crack Opening ◽  
Initial Crack ◽  
Effect Study ◽  
Small Scale ◽  
Opening Displacement ◽  
Critical Crack ◽  
Experimental Calibration ◽  
Brackish Ice

AbstractField-test equipment called FIFT (a Field Instrument for Fracture toughness Tests on ice) was used in both field and laboratory fracture-toughness tests on brackish sea ice from the Gulf of Bothnia. An experimental calibration was performed and a compliance expression was then derived for the Short Rod Chevron Notched (SRCN) specimen. Using the SRCN configuration, for which the initial crack growth is shown to be stable, and measured load-point displacements, preliminary crack-growth velocities are found. The obtained estimated crack velocity is, on average,ȧe= 20 ms−1, albeit with a large standard deviation. The results indicate that critical crack (crack-jumping) growth occurs. The apparent fracture toughness,KQ, was found to have a pronounced dependency on porosity in the form of brine volume. The results obtained are derived from a linearly elastic fracture mechanics (LEFM) theory. Consequently, the tests were designed to satisfy small-scale yielding requirements in terms of notch sensitivity and brittleness. The linearity of the load vs crack-opening displacement curves together with a size-effect study, showing that the specimen is notch-sensitive for grain-sizes ranging from 1.6 to nearly 100 mm, indicate that LEFM could be applicable.

Sign in / Sign up

Export Citation Format

Share Document