Investigation of Plastic Zone Development in Dynamic Tear Test Specimens

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Authors
  1. Koko, T.S.
  2. Gallant, B.K.
  3. Tobin, S.M.
Corporate Authors
Defence Research Establishment Atlantic, Dartmouth NS (CAN);MARTEC Ltd, Halifax NS (CAN)
Abstract
The J-Integral is an elastic-plastic fracture criterion, which permits measurement of the fracture toughness of a specimen that has been fractured after general yielding. However, an understanding of the ratio of plastic zone size (radius) to the crack tip blunting (stretch zone) required to determine the upper limit of temperature relative to full size transition curves where elastic plastic fracture becomes invalid. This study endeavours to acquire this ratio using finite element techniques. The development of the plastic zone in dynamic tear (DT) specimens and a non-standard three point bending fracture test specimen used to measure fracture properties was the main focus of the study. The ABAQUS finitie element software was used to model the elastic-plastic behaviour of the specimens. For the DT specimen, a crack was induced by pressing the notch, followed by fatigue cracking at a limit load level of 40% of the specimen limit load, whereas, the crack shape for the non-standard specimen was a fatigue crack defined at approximately 30% of the limit load. The shapes of these cracks were adequately modelled in the finite element analysis. The specimens were made of 350WT steel and 304 stainless steel materials. The specimens were loaded until fixed amounts of permanent deformation were recorded. TRUNCATED
Keywords
Dynamic Tear Transition Curve;Fracture transition;350WT steel;Stretch Zone Width;Plastic Zone Radius;Elastic Plastic Fracture Toughness
Report Number
DREA-CR-1999-095 — Contractor Report
Date of publication
01 Jul 1999
Number of Pages
69
DSTKIM No
CA000374
CANDIS No
512408
Format(s):
Hardcopy;Document Image stored on Optical Disk

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