The effect of free surface on fatigue crack behaviour

0319037 - ÚFM 2009 CN eng A - Abstract
Hutař, Pavel - Náhlík, Luboš - Knésl, Zdeněk
The effect of free surface on fatigue crack behaviour.
[Vliv volného povrchu na chování únavové trhliny.]
IWCMM18 - 18th International Workshop on Computational Mechanics of Materials. Beijing: Beijing Institute of Technology, 2008. s. 103-103.
[International Workshop on Computational Mechanics of Materials /18./. 07.10.2008-10.10.2008, Beijing]
R&D Projects: GA ČR GP106/06/P239; GA ČR GA101/08/1623
Institutional research plan: CEZ:AV0Z20410507
Keywords : vertex singularity * fatigue crack * lifetime estimation
Subject RIV: JL - Materials Fatigue, Friction Mechanics

The main focus of this work is on numerical investigations of the effect of free surface on fatigue crack behavior. Especially relatively thin structures, where vertex singularities are influenced together, are studied. The singularity exponents in vertex point vary between 0.5(corresponding to) and 0.33(corresponding to). With decrease of the structure thickness vertex singularity exponent increases. For really thin structures (t<1 mm) singular stress field around crack tip have the same manner through the thickness of the structure and stress singularity exponent is roughly constant in the relation with thickness. In the case of Poisson’s ratio higher than 0 the singularity exponent is significantly smaller than 0.5. Decrease of the stress singularity exponent for the same nominal loading leads generally to decrease of the fatigue crack growth rate.The estimated fatigue crack growth rate can help to provide a more reliable estimation of the fatigue life of the thin-walled structures.

Hlavním cílem práce je pomocí numerických simulací popsat chování únavové trhliny ovlivněné volným povrchem. Vlivem volného povrchu se mění singulární charakter napjatosti před čelem trhliny a může významě ovlivnit chování takovéto trhliny. Tyto koncepty vedou ke zpřesnění odhadů únavové životnosti tenkostěných struktur.
Permanent Link: http://hdl.handle.net/11104/0168299