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A short paper on T-stress of an interfacial crack in a bi-material strip
Wed, 2007-01-24 15:46 - Jae-Hyun Kim
The attached file is on T-stress of an interfacial crack in a bi-material strip. The geometry of the problem is the same with that of Suo and Hutchinson (1990, IJF). Using a conservation integral technique, a formula for T-stress is derived with two numerical factors.
Any comments are welcomed.
| Attachment | Size |
|---|---|
 T-stress-LettersFRAC_revised_ff.pdf | 221.98 KB |
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Comments
T-stress is still an active area in fracture mechanics
Dear Jae-Hyun,
Very nice paper. Your simplified results will be valuable to our fracture experiments such as DCB tests. Indeed, T-stress research is still an open area. Our paper on the T-stress changes across crack kinking will be published by ASME J of Applied Mechanics soon. Since an interfacial crack in a bi-material strip tends to kink into the weak part, the role of the T-stress is critical (as discussed by He and Hutchinson in 1989). We still have many topics on the T-stress to explore.
Roy
T-stress and crack stability
Dear Luoyu,
Thanks for your nice comments. I'm happy to hear that you have been interested in T-stress. Vlassak group in Harvard Univ. has conducted several fracture tests (DCB and 4 point bending) on a thin film layer sandwiched between two thick silicon substrates. The thin film is a low-k dielectric layer made of Organosilica Glass(it's very brittle). Oscillatory cracks (or wavy crack) have been observed in some specimens during 4 point bending tests. Our paper on T-stress was motivated by this observation. I have a discussion point:
- T-stress is a non-singular term in the eigen function expansion of a crack tip stress field. For an infinite homogeneous solid or bimaterial solid, it should be a good parameter for the crack stability. For a sandwiched thin layer(500nm thick), T-stress seems weak to govern the crack stability because it is the non-signular term. The crack in the sandwiched layer experiences a dramatic change in the stress state depending on its location in the layer(Fleck et al., 1991). I suspect the role of T-stress in this case. Would you comment this?