Influence of Specimen Geometry on the Random Load Fatigue Crack Growth

2009 ◽  
pp. 88-88-17
Author(s):  
JC Radon ◽  
K Nikbin
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Specimen Geometry ◽  
Random Load

Comparison of Fatigue Crack Growth Rates Between Different Specimen Geometries

2021 ◽  
Author(s):  
Yan-Hui Zhang ◽  
Matthew Doré
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Literature Review ◽  
Crack Growth ◽  
Compact Tension ◽  
Specimen Geometry ◽  
Single Edge ◽  
Single Edge Notch ◽  
Advantages And Disadvantages ◽  
Edge Notch

Abstract Most engineering components are subjected to cyclic loading in service and design against fatigue failure is often a key consideration in design. For fracture mechanics fatigue analysis, fatigue crack growth (FCG) tests are often required to determine the relevant Paris power law parameters for the material under the environment concerned. Standards allow use of different specimen geometries for FCG tests such as compact tension (CT), centre crack tension (CCT), single edge notch bend (SENB) and single edge notch tension (SENT). However, when selecting specimen geometry for fatigue crack growth rate (FCGR) testing, there is often doubt about which specimen geometry is more appropriate and whether they give similar FCGR. There is limited work to compare the FCGR between different specimen geometries. This paper first briefly introduces the guidance on FCG test specimen geometries in standards and compares the advantages and disadvantages of these specimen geometries. A comprehensive literature review is carried out to compare the FCGR data between different specimen geometries. FCGR tests are conducted on SENB, SENT and CCT specimens of C-Mn steel to investigate any effects of specimen symmetry/asymmetry and crack constraint on FCGR. Based on the literature review and test data, it is concluded that FCGR is independent of the specimen geometries examined.

A Novel Specimen Geometry for Fatigue Crack Growth in Vacuum

2019 ◽  
pp. 213-218
Author(s):  
L. M. S. Santos ◽  
C. Capela ◽  
F. V. Antunes ◽  
J. A. M. Ferreira ◽  
J. D. Costa ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Specimen Geometry

Effects of Specimen Geometry on Fatigue-Crack Growth Rates in Pipeline Steels

2008 ◽  
Author(s):  
J. M. Treinen ◽  
Ph. P. Darcis ◽  
J. D. McColskey ◽  
R. Smith ◽  
J. Merritt
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Rates ◽  
Compact Tension ◽  
Compact Tension Specimen ◽  
Specimen Geometry ◽  
Tension Specimen ◽  
Pipeline Steels ◽  
Crack Growth Rates

The effects of specimen geometry on the fatigue crack growth rates (FCGR) in API X65 and X100 pipeline steels were explored by use of the middle tension and compact tension specimen geometries. It was found that the specimen type has little influence on the stage II linear fatigue crack growth region for these steels. Furthermore, the FCGR behavior in the longitudinal and transverse directions was found to be nearly identical for both steels. Also of interest was a comparison of the FCGR results to the BS 7910 design curves, which showed a discrepancy between the results and the standard only at low delta K levels. A finite element analysis of the compliance relationships used to predict the crack lengths during testing of both specimen types revealed that the expression for both the middle tension specimen and the compact tension specimen were found to be valid. Although the curved geometry of the middle tension specimen caused slightly different compliance results, these differences did not appear to affect the FCGR results.

Crack closure at positive stresses during random load fatigue crack growth

1976 ◽  
Vol 11 (1) ◽  
pp. 32-38 ◽  
Author(s):  
W D Dover ◽  
N F Boutle
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Closure ◽  
Dynamic Range ◽  
Broad Band ◽  
Random Load ◽  
Fatigue Crack Closure ◽  
Closure Stress ◽  
Strain Fracture

Fatigue crack closure at positive stresses during broad band, random load fatigue crack growth, has been investigated. Tests were performed on centre-notched specimens made from an aluminium alloy (B.S. 2L 71). The closure stress was found to be dependent upon the material thickness, the mode of fracture and the stress ratio Q. Under plane strain fracture mode conditions it was found that the closure stress for 22 mm thick specimens was greater than that found with 6 mm thick specimens. This difference in closure behaviour produced a slower fatigue crack growth rate for the thicker specimens. In addition it was found that for a given r.m.s. stress the fatigue crack closure level only impinged upon the dynamic range at low mean stress levels.

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