Effect of notch root radius on the initiation and propagation of fatigue cracks

1972 ◽  
Vol 4 (2) ◽  
pp. 325-331 ◽  
Author(s):  
M.B.P. Allery ◽  
G. Birkbeck
Keyword(s):  
Notch Root ◽  
Fatigue Cracks ◽  
Root Radius ◽  
Notch Root Radius ◽  
Initiation And Propagation

Limits of Applicability of the Notch Failure Assessment Diagram

2018 ◽  
Author(s):  
Anthony J. Horn ◽  
Chris Aird
Keyword(s):  
Structural Integrity ◽  
Notch Root ◽  
Fatigue Cracks ◽  
Mechanical Damage ◽  
Root Radius ◽  
Integrity Assessment ◽  
Failure Assessment Diagram ◽  
Notch Root Radius ◽  
Failure Assessment ◽  
Sharp Crack

Structural integrity assessment codes such as R6 [1] and BS7910 [2] provide guidance on the assessment of flaws that are assumed to be infinitely sharp using the Failure Assessment Diagram (FAD). In many cases, such as fatigue cracks, this assumption is appropriate, however it can be pessimistic for flaws that do not have sharp tips such as those associated with lack of fusion, porosity or mechanical damage. Several Notch Failure Assessment Diagram (NFAD) methods have been proposed in the literature to quantify the additional margins that may be present for non-sharp defects compared to the margins that would be calculated if the defect were assumed to be a sharp crack. This paper uses mechanistic modelling to define the limits of applicability of the NFAD approach in terms of ρ/a, where ρ is the notch root radius and a is the notch depth. The work concludes that the NFAD can be used to assess notches with ρ/a values of up to unity.

Anomaly of Toughness Behavior with Notch-Root Radius

2009 ◽  
pp. 218-218-18
Author(s):  
KP Datta ◽  
WE Wood
Keyword(s):  
Notch Root ◽  
Root Radius ◽  
Notch Root Radius

A comparison between rapid expressions for evaluation of the critical J-integral in plates with U-notches under mode I loading

2011 ◽  
Vol 46 (8) ◽  
pp. 852-865 ◽  
Author(s):  
E Barati ◽  
F Berto
Keyword(s):  
Loading Condition ◽  
Control Volume ◽  
Notch Root ◽  
Critical Value ◽  
Fracture Load ◽  
Mode I ◽  
J Integral ◽  
Root Radius ◽  
Notch Root Radius ◽  
Mode I Loading

In this paper, some practical linear-elastic equations for evaluation of the critical value of the J-integral in plates with U-notches under mode I loading are presented and applied to brittle and quasi-brittle materials. The relationship between the J-integral and strain energy averaged over a well-defined control volume, depending on the static properties of the material, is applied, with the aim of obtaining the final expressions. It is found that these three proposed equations provide the same results, with any differences being negligible. By using one of these equations, one can evaluate Jcr and then predict the critical fracture load by means of the Jcr criterion. The results have shown that the critical value of the J-integral ( Jcr) is a function of the ratio of the material control radius to the notch-root radius ( Rc/ρ), the ratio of specimen width to notch depth ( w/ a), the notch acuity ( a/ρ), and the loading condition (tensile or bending loadings) in U-notches under mode I loading. However, the effect of the loading condition, a/ρ and w/ a ratios may be negligible. Therefore only the Rc/ρ ratio (i.e. the material properties and the notch-root radius of the specimen) affects Jcr.

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