Publication detail

Determination of local stress intensity factors at microstructurally tortuous crack fronts under remote mode II loading

ŽÁK, S. HORNÍKOVÁ, J. ŠANDERA, P. VOJTEK, T. POKLUDA, J.

Original Title

Determination of local stress intensity factors at microstructurally tortuous crack fronts under remote mode II loading

English Title

Determination of local stress intensity factors at microstructurally tortuous crack fronts under remote mode II loading

Type

conference paper

Language

en

Original Abstract

The real crack geometries are mostly not ideally smooth and fracture parameters calculated for cracks with tortuous fronts and rough flanks differ from results obtained for smooth cracks. The finite element methods allow us to determine fracture parameters for such kinds of cracks and, moreover, some useful analytical approaches can also be applied to simplified crack front geometries. Several authors already reported on these geometrically induced shielding effects but, in most cases, only the loading under the opening mode I was considered in the frame of simple 2D models of tortuous crack front. This work presents results of the investigation of local mixed-mode loading along a real-like, tortuous crack front loaded under the remote mode II. The employed numerical methods enabled us to get sufficiently precise values of all local components of loading modes I, II and III along the crack front. A comparison of these values with those obtained from analytical formulae related to a simplified form of the tortuous crack front with an equal linear roughness led to a very good agreement. The results could be used for a correction of the mode II effective fatigue threshold as measured for the polycrystalline ARMCO iron under an assumption of a straight precrack front. It is expected that such a correction, based on the roughness data of the real precrack, will shift the measured fatigue threshold data very close to those theoretical obtained from multiscale approaches.

English abstract

The real crack geometries are mostly not ideally smooth and fracture parameters calculated for cracks with tortuous fronts and rough flanks differ from results obtained for smooth cracks. The finite element methods allow us to determine fracture parameters for such kinds of cracks and, moreover, some useful analytical approaches can also be applied to simplified crack front geometries. Several authors already reported on these geometrically induced shielding effects but, in most cases, only the loading under the opening mode I was considered in the frame of simple 2D models of tortuous crack front. This work presents results of the investigation of local mixed-mode loading along a real-like, tortuous crack front loaded under the remote mode II. The employed numerical methods enabled us to get sufficiently precise values of all local components of loading modes I, II and III along the crack front. A comparison of these values with those obtained from analytical formulae related to a simplified form of the tortuous crack front with an equal linear roughness led to a very good agreement. The results could be used for a correction of the mode II effective fatigue threshold as measured for the polycrystalline ARMCO iron under an assumption of a straight precrack front. It is expected that such a correction, based on the roughness data of the real precrack, will shift the measured fatigue threshold data very close to those theoretical obtained from multiscale approaches.

Keywords

shear mode loading; micro-tortuous crack front; Compact-Tension-Shear specimen; geometrical shielding effect

Released

13.12.2017

Publisher

Elsevier

Pages from

254

Pages to

261

Pages count

8