scholarly journals Fatigue Life Evaluation Considering Fatigue Reliability and Fatigue Crack for FV520B-I in VHCF Regime Based on Fracture Mechanics

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 371 ◽  
Author(s):  
Jinlong Wang ◽  
Yuxing Yang ◽  
Jing Yu ◽  
Jingsi Wang ◽  
Fengming Du ◽  
...  

This paper focuses on the fatigue reliability analysis and the development of a new life model of reliability and crack growth mechanisms in FV520B-I (high strength martensitic-type stainless steels) in the very-high cycle fatigue (VHCF) regime, which haven’t been studied well. First, the fatigue test was carried out to clarify the fatigue failure mechanism in the very-high cycle regime. Based on the test results and fatigue reliability theory, the fatigue life distribution and P-S-N curves were modeled. A new fatigue life evaluation model for FV520B-I is proposed according to the fracture mechanics and classic life evaluation method. With the comprehensive application of P-S-N curves and a new proposed fatigue life evaluation model, a new assumption of a P-Sc-N curve is developed and verified, to quantitatively express the relationship between fatigue life, reliability and fatigue cracking. This is novel and valuable for further fatigue study of FV520B-I.

2013 ◽  
Vol 441 (1-3) ◽  
pp. 125-132 ◽  
Author(s):  
Shuhei Nogami ◽  
Arata Nishimura ◽  
Eichi Wakai ◽  
Hiroyasu Tanigawa ◽  
Takamoto Itoh ◽  
...  

2007 ◽  
Vol 345-346 ◽  
pp. 251-254
Author(s):  
Su Rok Sin ◽  
Sung Mo Yang ◽  
Hyo Sun Yu ◽  
Chai Won Kim ◽  
Hee Yong Kang

The welding quality of spot weldment is an important factor that significantly affects the strength, stiffness, safety, and other performance characteristics of vehicles. Therefore, quality control and fatigue life evaluation of spot weldment are necessary processes. This paper presents a method for determining the fatigue life of multi-lap spot weldment of a high strength steel sheet. In this method, the fatigue life is estimated by using the lethargy coefficient, which is the total defect coefficient according to rupture stress and time obtained by the quasi static tensile-shear test. Also, in this study, we modified the lethargy coefficient by using the welding current. And, we define a specific lapping constant, which is a characteristic constant of 2 or 3 lap weldments. The fatigue life obtained by the fatigue estimate equation, which contains a specific lapping constant was compared and verified with an experimental value. And we analyzed the relation of lap number, welding current and fatigue life. This method can save processing time and cost for predicting the life cycle of a structure.


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