Vliv různých materiálových růstových modelů na vypočtenou zbytkovou únavovou životnost železničních náprav

Influence of different crack propagation rate descriptions on the residual fatigue lifetime of railway axles

journal article in Scopus

en

The paper deals with an estimation of the residual fatigue lifetime of the railway axles. The railway axles can include some cracks either from manufacturing process or from previous loading operation. Because of cyclic loading of the railway axles there is a risk of fatigue failure of the railway axles with unacceptable consequences. Based on this fact, for conservative establishment of the residual fatigue lifetime of the railway axle is necessary to consider an existing crack in the railway axle during design process. The fatigue lifetime estimation of railway axles is very sensitive to used crack propagation rate description (e.g. v-K curve). Typical bending of this curve (knee) can be found in the vicinity of the threshold value in fatigue crack propagation rate dependence (typically v-K curve expressed in log-log coordinates). For accurate estimation of residual fatigue lifetime of the railway axle is necessary to use approximation of v-K curve that takes into account existence of the knee close to the threshold value of the stress intensity factor. The paper shows important differences between different crack propagation rate descriptions on the residual fatigue lifetime estimation of the railway axles. Results obtained can be used for safer design and operation of the railway axles.

Článek popisuje vliv užitých materiálových modelů pro popis růstové křivky (v-K křivky). V článku jsou porovnány 3 modely: Paris-Erdogan, NASGRO a Multilineární model. S těmito modely je výpočtem stanovena zbytková únavová životnost.

The paper deals with an estimation of the residual fatigue lifetime of the railway axles. The railway axles can include some cracks either from manufacturing process or from previous loading operation. Because of cyclic loading of the railway axles there is a risk of fatigue failure of the railway axles with unacceptable consequences. Based on this fact, for conservative establishment of the residual fatigue lifetime of the railway axle is necessary to consider an existing crack in the railway axle during design process. The fatigue lifetime estimation of railway axles is very sensitive to used crack propagation rate description (e.g. v-K curve). Typical bending of this curve (knee) can be found in the vicinity of the threshold value in fatigue crack propagation rate dependence (typically v-K curve expressed in log-log coordinates). For accurate estimation of residual fatigue lifetime of the railway axle is necessary to use approximation of v-K curve that takes into account existence of the knee close to the threshold value of the stress intensity factor. The paper shows important differences between different crack propagation rate descriptions on the residual fatigue lifetime estimation of the railway axles. Results obtained can be used for safer design and operation of the railway axles.

zbytková únavová životnost, únavová trhlina, šíření únavové trhliny, železniční náprava

residual fatigue lifetime, fatigue crack, fatigue crack propagation, railway axle

2015

30.01.2015

1013-9826

627

627

469–472

4