Abstract
Background:: Subcritical crack growth can occur in a brittle material when the stress intensity factor is smaller than the fracture toughness if an oxidizing agent (such as water) is present at the crack tip. Objective:: We present a novel bi-material beam specimen which can measure environmentally assisted crack growth rates. The specimen is “self-loaded” by residual stress and requires no external loading. Methods:: Two materials with different coefficient of thermal expansion are diffusion bonded at high temperature. After cooling to room temperature a subcritical crack is driven by thermal residual stresses. A finite element model is used to design the specimen geometry in terms of material properties in order to achieve the desired crack tip driving force. Results:: The specimen is designed so that the crack driving force decreases as the crack extends, thus enabling the measurement of the crack velocity versus driving force relationship with a single test. The method is demonstrated by measuring slow crack growth data in soda lime silicate glass and validated by comparison to previously published data. Conclusions:: The self-loaded nature of the specimen makes it ideal for measuring the very low crack velocities needed to predict brittle failure at long lifetimes.
| Original language | English |
|---|---|
| Pages (from-to) | 411-418 |
| Number of pages | 8 |
| Journal | Experimental Mechanics |
| Volume | 61 |
| Issue number | 2 |
| DOIs | |
| State | Published - Feb 2021 |
| Externally published | Yes |
Funding
The authors thank Matthew Brake, Michaela Negus, Diane Peebles, Jim Redmond, and Dennis Croessmann of Sandia National Laboratories for organization and support of the Nonlinear Mechanics and Dynamics (NOMAD) Institute. The authors also gratefully acknowledge support from Fracture Analysis Consultants, Inc. for donating a summer license of FRANC3D for use at the NOMAD Institute. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. The authors declare that they have no conflicts of interest. The authors thank Matthew Brake, Michaela Negus, Diane Peebles, Jim Redmond, and Dennis Croessmann of Sandia National Laboratories for organization and support of the Nonlinear Mechanics and Dynamics (NOMAD) Institute. The authors also gratefully acknowledge support from Fracture Analysis Consultants, Inc. for donating a summer license of FRANC3D for use at the NOMAD Institute. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy?s National Nuclear Security Administration under contract DE-NA0003525. The authors declare that they have no conflicts of interest.
Keywords
- Crack propagation
- Environmentally assisted crack growth
- Glass fracture
- Slow crack growth