3D Analyses of crack propagation in torsion
Journal Title: Frattura ed Integrità Strutturale - Year 2015, Vol 9, Issue 33
Abstract
The initiation and propagation of fatigue cracks during cyclic torsion loading was studied in a cast Al alloy (A357) with a relatively large (~500 μm) grain size. 2D observations, revealed that multi site crack initiation occur on the {111} slip planes exhibiting the highest slip activity (iso-strain Taylor analysis), preferentially on planes nearly perpendicular to the sample axis. Within the first grain, the cracks have a pronounced crystallographic propagation mode (mode II crack growth) and strongly interact with the grain boundaries. In situ 3D monitoring of torsion fatigue tests using synchrotron X-ray tomography reveal that propagation towards the interior of the samples occurs first along the sample periphery in mode II leading to relatively shallow cracks which penetrate towards the sample center only after a large number of cycles is reached .The values of mode I, II and III stress intensity factors have been calculated from finite element simulation at the tip of the shallow mode II crack. Those values are used to analyse the bulk propagation of the observed cracks.
Authors and Affiliations
D. Shiozawa, I. Serrano-Munoz, S. Dancette, C. Verdu, J. Lachambre
Keywords
Related Articles
- EP ID EP89593
- DOI 10.3221/IGF-ESIS.33.07
- Views 99
- Downloads 0
Crack growth threshold under hold time conditions in DA Inconel 718 – A transition in the crack growth mechanism
Aeroengine manufacturers have to demonstrate that critical components such as turbine disks, made of DA Inconel 718, meet the certification requirements in term of fatigue crack growth. In order to be more re...
Development of in-situ fatigue crack observing system for rotating bending fatigue testing machine
To substitute for a traditional replication technique, an in-situ fatigue crack observing system for rotating bending testing machine has been newly developed. For verifying performance of this observing system,...
Stress triaxiality influence on damaging micromechanisms in a pearlitic ductile cast iron
In the last decades, damaging micromechanisms in ductile cast irons (DCIs) have been widely investigated, considering both the matrix microstructure and the loading conditions influence. Considering the graphite...
Damage localization and rupture with gradient damage models
We propose a method of construction of non homogeneous solutions to the problem of traction of a bar made of an elastic-damaging material whose softening behavior is regularized by a gradient damage model. We show...
Local strain energy density to assess the multiaxial fatigue strength of titanium alloys
The present paper investigates the multiaxial fatigue strength of sharp V-notched components made of titanium grade 5 alloy (Ti-6Al-4V). Axisymmetric notched specimens have been tested under combined tension...