Vol. 4, No. 4, 2009

Download this article
Download this article For screen
For printing
Recent Issues

Volume 12
Issue 3, 249–351
Issue 2, 147–247
Issue 1, 1–146

Volume 11, 5 issues

Volume 10, 5 issues

Volume 9, 5 issues

Volume 8, 8 issues

Volume 7, 10 issues

Volume 6, 9 issues

Volume 5, 6 issues

Volume 4, 10 issues

Volume 3, 10 issues

Volume 2, 10 issues

Volume 1, 8 issues

The Journal
Cover
Editorial Board
Research Statement
Scientific Advantage
Submission Guidelines
Submission Form
Subscriptions
Author Index
To Appear
 
ISSN: 1559-3959
Brittle fracture beyond the stress intensity factor

C. T. Sun and Haiyang Qian

Vol. 4 (2009), No. 4, 743–753
Abstract

It is commonly believed that the fracture toughness of a brittle material can be characterized by a single parameter such as the stress intensity factor. In this study, it was demonstrated that when the crack is highly constrained, the first nonsingular opening stress term at the crack tip, in addition to the K-field (the singular stress term), is necessary to predict fracture. Fracture experiments were conducted using plexiglass specimens with a center crack. Relatively rigid metallic end tabs were used to generate boundary constraints on the specimen. The level of constraint was varied by varying the gage length between the end tabs. For a given crack length, the fracture load increases as the gage length decreases. If the stress intensity factor is used to determine the corresponding fracture toughness of plexiglass, the experimental data would indicate that the fracture toughness decreases as the gage length decreases. This is equivalent to saying that the fracture toughness of a brittle material can be affected by boundary conditions. It was shown that this behavior is the result of a diminishing size of the K-dominance zone and that the stress intensity factor alone cannot fully capture the fracture force. A new constant parameter was introduced to account for the effect of the near-tip nonsingular stress field on fracture.

Keywords
stress intensity factor, K-dominance, fracture load, nonsingular stress, plexiglass
Milestones
Received: 10 March 2008
Revised: 7 October 2008
Accepted: 6 December 2008
Published: 7 August 2009
Authors
C. T. Sun
Purdue University
School of Aeronautics and Astronautics
701 W. Stadium Ave
W. Lafayette, IN 47907
United States
Haiyang Qian
Purdue University
School of Aeronautics and Astronautics
701 W. Stadium Ave
W. Lafayette, IN 47907
United States