Paper Title:

A Fracture Mechanics Investigation on Crack Growth in Massive Forming

Periodical Materials Science Forum (Volume 482)
Main Theme Materials Structure & Micromechanics of Fracture
Edited by Jaroslav Pokluda
Pages 339-342
DOI 10.4028/www.scientific.net/MSF.482.339
Citation Gernot Trattnig et al., 2005, Materials Science Forum, 482, 339
Online since April, 2005
Authors Gernot Trattnig, Christof Sommitsch, Reinhard Pippan
Keywords Crack Growth, Crack Opening Displacement, Fracture Toughness, Stress Triaxiality
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Abstract

To understand the crack growth in massive forming and to consequentially avoid crack growth in workpieces, it is necessary to investigate its dependence on the crack depth and thus on the state of hydrostatic stress. Prior work shows that the crack opening displacement (COD) for shallow cracked tension specimens with low stress triaxiality is twice as high as for deep cracked specimens with high stress triaxiality. This work examines the crack growth in compression specimens with pre-cracked cylindrical upsetting samples. The compression samples were cut in the stress symmetry plane in order to observe crack initiation and crack growth by a single specimen technique. In this way it is possible to observe blunting, crack initiation and crack growth inside the upsetting specimens. The resulting COD does not differ significantly from the values achieved in tension samples with short surface cracks.