Optical methods for measurement of fatigue crack closure: moiré interferometry and digital image correlation

2010 ◽  
Vol 33 (12) ◽  
pp. 778-790 ◽  
Author(s):  
D. NOWELL ◽  
R. J. H. PAYNTER ◽  
P. F. P DE MATOS
Keyword(s):  
Fatigue Crack ◽  
Digital Image Correlation ◽  
Crack Closure ◽  
Digital Image ◽  
Moiré Interferometry ◽  
Image Correlation ◽  
Optical Methods ◽  
Moire Interferometry ◽  
Fatigue Crack Closure

Investigation of thermal effects on fatigue crack closure using multiscale digital image correlation experiments

2014 ◽  
Vol 61 ◽  
pp. 10-20 ◽  
Author(s):  
Mallory C. Casperson ◽  
Jay D. Carroll ◽  
John Lambros ◽  
Huseyin Sehitoglu ◽  
Robert H. Dodds
Keyword(s):  
Fatigue Crack ◽  
Digital Image Correlation ◽  
Crack Closure ◽  
Digital Image ◽  
Thermal Effects ◽  
Image Correlation ◽  
Fatigue Crack Closure

Techniques for Experimental Measurement of Fatigue Crack Closure

2007 ◽  
Vol 7-8 ◽  
pp. 3-9 ◽  
Author(s):  
David Nowell
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Crack Closure ◽  
Experimental Measurement ◽  
Moiré Interferometry ◽  
Experimental Results ◽  
Moire Interferometry ◽  
Fatigue Crack Closure ◽  
Closure Models ◽  
Important Phenomenon

Fatigue crack closure is an important phenomenon which needs to be taken into account in the development of models for crack propagation. This paper presents an overview of techniques for measuring crack closure. The moiré interferometry approach is described in more detail and some experimental results are presented and compared with the predictions of closure models.

Experimental Study of Fatigue Crack Initiation and Strain Evolution around a Micro-Void by In Situ SEM and Digital Image Correlation

2017 ◽  
Vol 754 ◽  
pp. 75-78 ◽  
Author(s):  
De Qiang Wang ◽  
Ming Liang Zhu ◽  
Fu Zhen Xuan
Keyword(s):  
Fatigue Crack ◽  
Digital Image Correlation ◽  
Crack Initiation ◽  
Digital Image ◽  
Early Stage ◽  
Fatigue Crack Initiation ◽  
Image Correlation ◽  
Dominant Factor ◽  
Strain Evolution

Fatigue crack initiation stage occupies a large proportion of total fatigue life in modern engineering materials and structures which are often designed under lower service loading conditions. In this paper, the fatigue crack initiation behavior from a micro-void in a small-scale specimen was studied in-situ in SEM. Surface morphologies were monitored in-situ and images were taken during interrupted tests at selected number of cycles, and displacement and strain map around the void was calculated based on digital image correlation (DIC) technique. The results indicated that the strain evolution near the micro-void could be divided into stages, before crack initiation. The strain increasing rate was fast in the early stage and slower in the second stage. A critical cyclic strain value for fatigue crack initiation from the micro-void was obtained around 9%, and was believed to be the dominant factor for early stage of fatigue damage.

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