The peculiarities of fatigue process zone formation of structural materials
Roman Chepil 1  
,   Volodymyr Vira 2  
,   Yevhen Kharchenko 2, 3  
,   Volodymyr Kulyk 2  
,   Zoia Duriagina 2, 4  
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Karpenko Physico-Mechanical Institute of the NAS of Ukraine_1, Naukova Str. 5, 79060 Lviv, Ukraine
Lviv Polytechnic National University_2, S. Bandery Str. 12, 79013 Lviv, Ukraine
University of Warmia and Mazury in Olsztyn, Faculty of Technical Science_3, Oczapowskiego str. 11D, 10-736 Olsztyn, Poland
The John Paul II Katholic Uniwersity of Lublin, Faculty of Physical Chemistry and Physicochemical Fundamentals of Environmental Engineering_4, Racławickie Al. 14, 20-950 Lublin, Poland
Yevhen Kharchenko   

Lviv Polytechnic National University_2, \nS. Bandery Str. 12, 79013 Lviv, Ukraine, ul. Oczapowskiego 11E, pok. 126, 10-736 Olsztyn, Polska
Submission date: 2018-05-26
Final revision date: 2018-07-31
Acceptance date: 2018-09-03
Online publication date: 2018-09-04
Publication date: 2018-09-04
Diagnostyka 2018;19(4):27–32
It is shown that with a cyclic loading in the vicinity of the stress concentrator within the static and cyclic plastic zones, a specific volume of material is gradually formed – the fatigue process zone. Its size d* determines the length of non-propagated cracks or safety defects in the material and can be a determining factor in the diagnosis of material damage. For these materials, the size d* does not depend a lot on the type and geometric characteristics of the stress concentrator. It can be determined by laboratory conditions. While detecting the defects which are longer than d*, it is decided to reduce the intervals between inspections of the construction element, repair or replace it.
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