Applicability of a Deterministic Approach to Transfer the Minimum Fracture Toughness Between Different Temperatures in the DBTT Region

2016 ◽  
Author(s):  
Toshiyuki Meshii ◽  
Teruhiro Yamaguchi ◽  
Koki Fukinbara
Keyword(s):  
Fracture Toughness ◽  
Transition Temperature ◽  
Crack Opening ◽  
Crack Tip ◽  
Deterministic Approach ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Different Temperatures ◽  
Crack Opening Stress ◽  
Crack Tip Opening

In this paper, we demonstrate that a deterministic approach requiring only tensile test data for different temperatures has a possibility to predict the minimum fracture toughness for these temperatures. The material is assumed to be in the Ductile-to-Brittle-Transition Temperature (DBTT) region. The approach was based on one of the authors’ finding that the critical stress σ22c of the modified Ritchie-Knott-Rice criterion is correlated with the minimum fracture toughness and shows very small scatter and is specimen configuration independent. The criterion predicts onset of cleavage fracture of a material in the DBTT transition temperature region, when the crack-opening stress σ22 measured at a distance from the crack-tip equal to four times the crack-tip opening displacement δt exceeds a critical value σ22c. The proposed approach is expected to overcome some inconveniences which recent studies have reported to the Master Curve parameters vary with size and temperature.

Plastic relaxation at a crack tip by asymmetric slip

1988 ◽  
Vol 418 (1854) ◽  
pp. 261-280 ◽  
Keyword(s):  
Slip Band ◽  
Crack Opening ◽  
Crack Tip ◽  
Friction Stress ◽  
Small Scale ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Sharp Crack ◽  
Scale Yielding ◽  
Crack Tip Opening

Relaxation at a sharp crack tip by a single slip band is considered. It is shown that for mixed-mode loading of a plane crack in an isotropic medium there is a unique angle between the slip band and the crack for which the energy release rate (or stress intensity factor) of the crack can be reduced to zero. For such a slip-band calculations are made of the slipband length and the crack-opening displacement as a function of the loading, crack length and friction stress acting on dislocations in the slip band. For small-scale yielding, a simple model is discussed that gives a good approximation to the crack-tip opening displacement and slip-band angle.

scholarly journals Applicability of the Modified Ritchie-Knott-Rice Failure Criterion to Examine the Feasibility of Miniaturized Charpy Type SE(B) Specimens

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Toshiyuki Meshii ◽  
Teruhiro Yamaguchi ◽  
Yuma Higashino
Keyword(s):  
Cleavage Fracture ◽  
Failure Criterion ◽  
Critical Stress ◽  
Small Difference ◽  
Crack Opening ◽  
Width Ratio ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Crack Opening Stress ◽  
Crack Tip Opening

This paper examined whether the modified Ritchie-Knott-Rice (RKR) failure criterion can be applied to examine the feasibility of miniaturized Charpy type SE(B) specimens of thickness-to-width ratio B/W=1. The modified RKR failure criterion considered in this paper is the (4δt,σ22c) criterion which predicts the onset of cleavage fracture when the midplane crack-opening stress measured at a distance equal to four times the crack-tip opening displacement, denoted as σ22d, exceeds a critical stress σ22c. Specimens with B values of 25, 10, 3, and 2 mm (denoted as 25t, 10t, 3t, and 2t specimens, resp.) manufactured with 0.55% carbon steel were tested at 20°C. The results showed that the modified RKR criterion could appropriately predict the occurrence of cleavage fracture accompanied by negligibly small stable crack extension (denoted as KJc fracture) naturally for the 25t and 10t specimens. The modified RKR criterion could also predict that KJc fracture does not occur for the 2t specimen. The σ22c obtained from specimens for the 25t and 10t specimens exhibited only a small difference, indicating that the Jc obtained from the 10t specimens can be used to predict the Jc that will be obtained with the 25t specimens.

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.

The Prediction of Fatigue Crack Opening Behavior Using Cyclic Crack Tip Opening Displacement by Finite Element Analysis

2006 ◽  
Vol 324-325 ◽  
pp. 295-298 ◽  
Author(s):  
Hyeon Chang Choi
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Crack ◽  
Crack Opening ◽  
Crack Tip ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Element Analysis ◽  
Element Size ◽  
Crack Tip Opening

An elastic-plastic finite element analysis (FEA) is performed to examine the opening behavior of fatigue crack, where the contact elements are used in the mesh of the crack tip area. The relationship between fatigue crack opening behavior and cyclic crack tip opening displacement was studied in the previous study. In this paper, we investigate the effect of the element size when predict fatigue crack opening behavior using the cyclic crack tip opening displacement obtained from FEA. The cyclic crack tip opening displacement is well related to fatigue crack opening behavior.

A Two-Parameter Description of the Behaviour of a Process Zone at a Crack Tip: Relation Between the Parameters

2005 ◽  
Author(s):  
E. Smith
Keyword(s):  
Process Zone ◽  
Crack Opening ◽  
Crack Tip ◽  
Relative Displacement ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Power Series Expansions ◽  
Elastic Crack ◽  
Crack Tip Opening ◽  
Crack Faces

The relative displacement of the crack faces and the tensile stress ahead of a Mode I elastic crack tip can be expressed, in the immediate vicinity of the tip, by two-term power series expansions, the two terms being associated with the stress intensity factor KI and a dimensionless parameter g0. These parameters feature prominently in cohesive process zone models of a crack tip with regard to the crack tip opening displacement vT, process zone size s, the crack opening area A and the effective opening area AD of the process zone. This paper shows that KI and g0 depend upon each other via a relation which is dependent upon the geometrical configuration but is independent of the configuration’s loading pattern.

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