Brittle Fracture from a Sliding Hertzian Contact

1994 ◽  
Vol 208 (6) ◽  
pp. 409-415 ◽  
Author(s):  
D A Hills ◽  
R L Munisamy ◽  
D Nowell ◽  
A G Atkins
Keyword(s):  
Fracture Toughness ◽  
Brittle Fracture ◽  
Brittle Material ◽  
Spherical Indenter ◽  
Crack Spacing ◽  
Hertzian Contact ◽  
Sliding Speed ◽  
Simplified Method

A simplified method of analysing the characteristic horseshoe cracks appearing behind a spherical indenter sliding along the surface of a brittle material, is described. The technique provides a reliable means of estimating the fracture toughness of the material and an explanation of the inter-crack spacing, which is found to be independent of the sliding speed.

2 1/4% NICKEL STEEL

Alloy Digest ◽  
1980 ◽  
Vol 29 (11) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Brittle Fracture ◽  
Physical Properties ◽  
Heat Treating ◽  
Pressure Vessels ◽  
Nickel Steel ◽  
Subzero Temperatures ◽  
Steel Mills ◽  
Resistance To Brittle Fracture

Abstract The 21/4% Nickel Steel possesses a combination of moderate strength and superior resistance to brittle fracture at subzero temperatures. It is one of the most economical materials for the construction of equipment to operate at temperatures as low as -90 F. It is intended primarily for welded pressure vessels. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SA-378. Producer or source: Alloy steel mills and foundries.

Evaluation of flexural fracture toughness for quasi-brittle structural materials using a simple test method

2002 ◽  
Vol 29 (4) ◽  
pp. 567-575 ◽  
Author(s):  
M.M Reda Taha ◽  
X Xiao ◽  
J Yi ◽  
N G Shrive
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Brittle Fracture ◽  
High Performance ◽  
High Performance Concrete ◽  
Fibre Reinforced Concrete ◽  
Simple Test ◽  
Elastic Crack ◽  
Fracture Performance ◽  
Brittle Fracture Mechanics

As new structural concepts such as partial prestressing and steel-free bridge decks are more widely accepted and used, there is an increasing need for a reliable and reproducible fracture performance criterion that can describe resistance to crack growth. The required criterion should also be easy to determine experimentally so that it can be incorporated in structural specifications. The nonlinear behaviour of concrete and masonry materials suggested that quasi-brittle fracture mechanics approaches may be the most suitable for determining their fracture performance. The effective elastic crack model originally developed by Karihaloo and Nallathambi (1989) was modified to evaluate the critical crack depth under pure flexural stresses. A computer program was developed to calculate this depth iteratively from the experimental results. An experimental programme examining the fracture performance of four different structural materials (high performance concrete, mortar, fibre reinforced concrete, and masonry units) was carried out to examine the applicability of the model. As no post-peak data are required for the analysis, the model allows the use of a simple test setup to evaluate the fracture performance of quasi-brittle materials experimentally.Key words: fracture toughness, linear elastic fracture mechanics (LEFM), elastoplastic fracture mechanics (EPFM), quasi-brittle fracture mechanics, effective elastic crack, high performance concrete, masonry, fibre reinforced concrete.

Modification of Pre-Cracked Charpy Specimens for Surveillance Specimen Programs

2009 ◽  
Author(s):  
Boris Margolin ◽  
Vladimir Nikolaev ◽  
Valentin Fomenko ◽  
Lev Ryadkov
Keyword(s):  
Experimental Data ◽  
Finite Element Method ◽  
Fracture Toughness ◽  
Finite Element ◽  
Brittle Fracture ◽  
Stress And Strain ◽  
Test Results ◽  
Deep Side ◽  
Strain Fields ◽  
Calculation Analysis

Application of pre-cracked Charpy specimens with various depth of side-grooves is considered for fracture toughness prediction. Recommendations for prediction of temperature dependence of fracture toughness are given when using small-sized specimens with deep side-grooves. Test results of about 500 specimens, cut from materials with various degrees of embrittlement are presented. On the basis of 3D calculations by finite element method the procedure used in standard ASTM E 1921 for calculation of Ke and J, is developed for bending specimens with deep side-grooves. An attempt is undertaken to explain the obtained experimental data from the standpoints of the available criteria of brittle fracture based on calculation analysis of stress and strain fields (SSF) of SE(B)-10 specimens with various depths of side-grooves.

Fracture Assessment of Welded Joint With Geometrical Discontinuity Using the Weibull Stress

2006 ◽  
Author(s):  
Satoshi Igi ◽  
Takahiro Kubo ◽  
Masayoshi Kurihara ◽  
Fumiyoshi Minami
Keyword(s):  
Fracture Toughness ◽  
Brittle Fracture ◽  
Welded Joint ◽  
Fracture Toughness Test ◽  
Geometrical Condition ◽  
Stress Criterion ◽  
Toughness Test ◽  
Fracture Assessment ◽  
Geometrical Discontinuity ◽  
Weibull Stress

Recently the Weibull stress is used as a fracture driving force parameter in fracture assessment. The Weibull stress is derived from a statistical analysis of local instability of micro cracks leading to brittle fracture initiation. The critical Weibull stress is expected to be a critical parameter independent of the geometrical condition of specimens. Fracture toughness test using 3-point bending and tensile tests of welded joint specimens with geometrical discontinuity were conducted in order to study the applicability of fracture assessment procedure based on Weibull stress criterion. Steel plates prepared for this study had tensile strength of 490 MPa for structural use. Two kinds of welded joint specimens, “one-bead welded joint” and “multi-pass welded joint” were prepared for fracture toughness test by using gas metal are welding. In tensile test specimen, corner flaws were introduced at the geometrical discontinuity part at where stress concentration is existed. Three dimensional elastoplastic finite element analyses were also carried out using the welded joint specimen models in order to calculate the Weibull stress. The critical loads for brittle fracture predicted by the Weibull stress criterion from CTOD test results of one-bead and multi-pass welded joint specimens show fairly good agreement with experimental results of welded joint specimens with geometrical discontinuity.

Limit Plastic Collapse on Remaining Ligament of Flawed Welds for ECA Application

2014 ◽  
Author(s):  
Antonio Carlucci ◽  
Kamel Mcirdi
Keyword(s):  
Fracture Toughness ◽  
Brittle Fracture ◽  
Mechanical Strain ◽  
Plastic Collapse ◽  
Fracture Toughness Test ◽  
Element Analysis ◽  
Critical Fracture ◽  
Failure Assessment ◽  
The One ◽  
Girth Welds

Engineering Critical Assessments (ECAs) are routinely used to provide defect acceptance criteria for pipelines girth welds. The Failure Assessment Diagram (FAD) concept is the most widely used methodology for elastic-plastic fracture mechanics analysis of structural components and adopted by standards/documents including BS7910 [1], API579-1/ASME FFS-1 [2], R6 [3]. It is defined by two criterion Kr and Lr which describe the interaction between brittle fracture and fully ductile rupture: Kr measures the proximity to brittle fracture whereas Lr reflects the closeness to plastic collapse. The BS7910 FAD level 2B is the most employed for assessment of flaws under mechanical strain lower than 0.4%, the FAD associated is material-specific and it based on single toughness value obtained from CTOD test, the latter-on gives no information about the tearing initiation. The objective of this paper is to propose an approach for determination of the critical fracture toughness (associated to zero-tearing: JΔa=0). This approach is based on the comparison between the load-CMOD curve provided from a fracture toughness test to the one obtained by Finite Element Analysis (FEA). The goals is to propose a conservative guidance on how to identify a remote strain level below which it may be considered guaranteed the integrity of the remaining ligament.

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