Effects of prior ductile tearing on cleavage fracture in the ductile-to-brittle transition region

Experimental studies demonstrate a significant effect of specimen size, a/W ratio and prior ductile tearing on cleavage fracture toughness values ($J\sb{c}$) measured in the ductile-to-brittle transition region of ferritic materials. In the lower-transition region, cleavage fracture often occurs under conditions of large-scale yielding but without prior ductile crack extension. The increased toughness develops when plastic zones formed at the crack tip interact with nearby specimen surfaces which relaxes crack-tip constraint (stress triaxiality). In the mid-to-upper transition region, small amounts of ductile crack extension (typically $<$1-2 mm) routinely precede termination of the ${J-\Delta a}$ curve by brittle fracture. Large-scale yielding, coupled with small amounts of ductile tearing, magnifies the impact of small variations in microscale material properties on the macroscopic fracture toughness which contributes to the large amount scatter observed in measured $J\sb{c}$-values.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Civil and Environmental Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Tang, Ming

Contributors dc:contributor

• Dodds, Robert H., Jr.

• Applied Mechanics
• Engineering, Civil
• Engineering, Mechanical

Statement dc:rights

• Copyright 1994 Tang, Ming

Language dc:language

eng

Identifier

AAI9512567
(UMI)AAI9512567

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/22211