scholarly journals РОЗРАХУНКИ ДЕТАЛЕЙ НА НАДІЙНІСТЬ ТА ДОВГОВІЧНІСТЬ ЗА КРИТЕРІЄМ ВТОМЛЕНІСНОЇ МІЦНОСТІ

2019 ◽  
Vol 126 (5) ◽  
pp. 56-62
Author(s):  
Л. М. Березін ◽  
М. М. Рубанка
Keyword(s):  
Fatigue Strength ◽  
Equivalent Stress ◽  
Estimate Reliability ◽  
Cylindrical Spiral

Development  of  the  basic  provisions  for  determination  of  the  equivalent  stress  in accordance with the spectrum of the load of cylindrical spiral springs of the overload release clutches of the rotatory  impeller  breaker  mills  with  the  further  use  of  such  basic  provisions  in  calculations  aimed  to estimate reliability and durability of details by criterion of fatigue strength.

scholarly journals Determination of the Vertical Load on the Carrying Structure of a Flat Wagon with the 18–100 and Y25 Bogies

2021 ◽  
Vol 11 (9) ◽  
pp. 4130
Author(s):  
Oleksij Fomin ◽  
Alyona Lovska ◽  
Václav Píštěk ◽  
Pavel Kučera
Keyword(s):  
Mathematical Model ◽  
Fatigue Strength ◽  
Service Life ◽  
Dynamic Characteristics ◽  
Dynamic Load ◽  
Field Tests ◽  
Vertical Load ◽  
Mathcad Software ◽  
The Mathematical Model

The study deals with determination of the vertical load on the carrying structure of a flat wagon on the 18–100 and Y25 bogies using mathematic modelling. The study was made for an empty wagon passing over a joint irregularity. The authors calculated the carrying structure of a flat wagon with the designed parameters and the actual features recorded during field tests. The mathematical model was solved in MathCad software. The study found that application of the Y25 bogie for a flat wagon with the designed parameters can decrease the dynamic load by 41.1% in comparison to that with the 18–100 bogie. Therefore, application of the Y25 bogie under a flat wagon with the actual parameters allows decreasing the dynamic loading by 41.4% in comparison to that with the 18–100 bogie. The study also looks at the service life of the supporting structure of a flat wagon with the Y25 bogie, which can be more than twice as long as the 18–100 bogie. The research can be of interest for specialists concerned with improvements in the dynamic characteristics and the fatigue strength of freight cars, safe rail operation, freight security, and the results of the research can be used for development of innovative wagon structures.

Modeling of Fatigue Slip Bands and Application to Notch Fatigue Problems

2008 ◽  
Author(s):  
Hiroshi Matsuno
Keyword(s):  
Fatigue Strength ◽  
Slip Band ◽  
Equivalent Stress ◽  
Cyclic Stress ◽  
Empirical Equations ◽  
Fundamental Idea ◽  
Slip Bands ◽  
Heat Treated ◽  
Fatigue Data ◽  
Stress Ratios

In the present paper, equivalent stress ratios (REQ-ratios), which have been proposed as parameters for correspondence between cyclic stress conditions of notched and unnotched specimens, are reviewed. The REQ-ratios are formulated based on a concept of plastic adaptation hypothesized for a fatigue slip band from a viewpoint of macro-mechanics. A method for diagramming fatigue strength of metals based on the parameter of the REQ-ratios is newly proposed. The method diagramming together the fatigue strength of notched and unnotched specimens is applied not only to fatigue problems of usually annealed, normalized and heat-treated materials but also to those of severely heat-treated and surface-treated ones. Fatigue strength diagrams are characterized with two types of fatigue strength: σw1 and σw2. The character of σw2 appears not only in specimens with sharp notches but also in unnotched specimens fatigue-tested at lower RN-ratios. Criteria on fatigue strength σw1 and σw2 are derived from the fatigue strength diagrams and formulated as empirical equations. Characteristics of fatigue slip bands are reviewed and two types of fatigue mechanisms are proposed related with fatigue strength σw1 and σw2 from a viewpoint of micro-mechanics. Consequently, it is found that the hypothesis of plastic adaptation is a very useful and fundamental idea for modeling a fatigue slip band and also for analyzing fatigue data of practical metals and alloys.

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