Publication detail

Near-threshold Fatigue Crack Propagation under Mixed-mode II+III in ARMCO Iron

VOJTEK, T. POKLUDA, J. ŠANDERA, P. HORNÍKOVÁ, J. SLÁMEČKA, K. PIPPAN, R. HOHENWARTER, A.

Original Title

Near-threshold Fatigue Crack Propagation under Mixed-mode II+III in ARMCO Iron

English Title

Near-threshold Fatigue Crack Propagation under Mixed-mode II+III in ARMCO Iron

Type

conference paper

Language

en

Original Abstract

The paper is dedicated to experiments on near-threshold fatigue cracks under mixed-mode II+III in the ARMCO iron. The aim is to find the intrinsic (effective) threshold value of stress intensity factor (SIF) range in the mixed mode II+III and to compare it to those in modes II, III as well as to elucidate the crack growth mechanism. In this paper we only focus on the mixed-mode II+III experiment. Cylindrical bars with circumferential cracked notch were loaded by shear force. The notch is located in the middle of the bar and, therefore, no bending moment is present. Pre-cracks were created by compressive cyclic loading in mode I to obtain smooth fracture surfaces. After the experiment, the specimens were fractured under very low temperature or by cyclic tensile loading. The circumferential crack was loaded by different combination of modes II and III. The SIFs in mode II and III were numerically calculated using FEM. Two simple formulae were used to evaluate the effective mixed-mode SIF. The crack path and the surface topography were studied by means of a 3D reconstruction of fracture surfaces using stereo pairs of SEM images of the fracture surface (stereophotogrammetry in SEM). Differences between crack paths (and associated morphologies) under modes II, III and II+III were analyzed and statistically described in terms of local inclination and twisting angles.

English abstract

The paper is dedicated to experiments on near-threshold fatigue cracks under mixed-mode II+III in the ARMCO iron. The aim is to find the intrinsic (effective) threshold value of stress intensity factor (SIF) range in the mixed mode II+III and to compare it to those in modes II, III as well as to elucidate the crack growth mechanism. In this paper we only focus on the mixed-mode II+III experiment. Cylindrical bars with circumferential cracked notch were loaded by shear force. The notch is located in the middle of the bar and, therefore, no bending moment is present. Pre-cracks were created by compressive cyclic loading in mode I to obtain smooth fracture surfaces. After the experiment, the specimens were fractured under very low temperature or by cyclic tensile loading. The circumferential crack was loaded by different combination of modes II and III. The SIFs in mode II and III were numerically calculated using FEM. Two simple formulae were used to evaluate the effective mixed-mode SIF. The crack path and the surface topography were studied by means of a 3D reconstruction of fracture surfaces using stereo pairs of SEM images of the fracture surface (stereophotogrammetry in SEM). Differences between crack paths (and associated morphologies) under modes II, III and II+III were analyzed and statistically described in terms of local inclination and twisting angles.

Keywords

mixed mode, stress intensity factor, crack growth, ARMCO iron

RIV year

2012

Released

26.08.2012

Location

Kazan

ISBN

978-5-905576-18-8

Book

19th European Conference on Fracture

Pages from

188

Pages to

193

Pages count

6

Documents

BibTex


@inproceedings{BUT95956,
  author="Tomáš {Vojtek} and Jaroslav {Pokluda} and Pavel {Šandera} and Jana {Horníková} and Karel {Slámečka} and Reinhard {Pippan} and Anton {Hohenwarter}",
  title="Near-threshold Fatigue Crack Propagation under Mixed-mode II+III in ARMCO Iron",
  annote="The paper is dedicated to experiments on near-threshold fatigue cracks under mixed-mode II+III in the ARMCO iron. The aim is to find the intrinsic (effective) threshold value of stress intensity factor (SIF) range in the mixed mode II+III and to compare it to those in modes II, III as well as to elucidate the crack growth mechanism. In this paper we only focus on the mixed-mode II+III experiment. Cylindrical bars with circumferential cracked notch were loaded by shear force. The notch is located in the middle of the bar and, therefore, no bending moment is present. Pre-cracks were created by compressive cyclic loading in mode I to obtain smooth fracture surfaces. After the experiment, the specimens were fractured under very low temperature or by cyclic tensile loading. The circumferential crack was loaded by different combination of modes II and III. The SIFs in mode II and III were numerically calculated using FEM. Two simple formulae were used to evaluate the effective mixed-mode SIF. The crack path and the surface topography were studied by means of a 3D reconstruction of fracture surfaces using stereo pairs of SEM images of the fracture surface (stereophotogrammetry in SEM). Differences between crack paths (and associated morphologies) under modes II, III and II+III were analyzed and statistically described in terms of local inclination and twisting angles.",
  booktitle="19th European Conference on Fracture",
  chapter="95956",
  howpublished="electronic, physical medium",
  year="2012",
  month="august",
  pages="188--193",
  type="conference paper"
}