Úprava Walkerova popisu vlivu asymetrie cyklu

Modification of Walkers description of cycle asymmetry influence

journal article - other

Czech

Walkeruv pristup popisu vlivu asymetrie cyklu ve vysokocyklové oblasti sestáváv s nasobením faktorem Pm kde P je jeden z pouzitých parametru asymetrie definovany pomocí kvocientu maxima napěti a amplitudy. Tento pristup může být pouzit i pro nizkocyklovou oblast. Potíze se objevují v případě vyshokých hodnot parametru P, kdy se objevují potíže pri konstrukci Haighova diagramu.

Walkers Approach of the description of the influence of loading cycle asymmetry in the high-cycle region consists in multiplying by a factor of Pm where P is one of used asymmetry parameters, defined by the quotien of maximum stress and stress amplitude. This approach can be relatively simply generalized also for low-cycle region as shown by the authors last year. Certain difficulty appears for high values parameter P when an unacceptable relation UTS < sigma c Pm (sigma c means fatigue limit) can be obtained. It has a very unpleasant consequence in the Haigh diagram construction: the curve does not cross the UTS value on mean stress axis as asked. The paper proposes a modification which is identical with walkers approach for lower values of asymmetry parameter P and, on the other hand, does not allow to overstep the UTS value for high values of parameter P. The advantage of this modification is best presented in the Haigh diagram.

Fatigue, Walkers approach, Haigh diagram

KOHOUT, J., VĚCHET, S.

2. 9. 2002

1335-0803

Materiálové inžinierstvo

9

3/2002

Slovak Republic

125

128

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