Microcracking due to grain boundary sliding in S2 ice under uniaxial compression
- Massachusetts Institute of Technology, Cambridge, MA (United States)
- National Institute of Standards, Gaithersburg, MD (United States)
The role of grain boundary sliding is examined as a possible mechanism for nucleation and growth of microcracks in polycrystalline S2 ice, under compression. The loading rate is fast enough so that the polycrystal response is almost linear. A repetitive unit cell model is used to determine the stresses and strains within the grains; the boundary value problem is solved by the finite element method. Simulations show that the influence of the elastic mismatch between neighboring grains (the elastic anisotropy mechanism) on microcracking stress is not strong. Indeed, if all grain boundary sliding is prevented, and only the elastic anisotropy mechanism is considered, the stresses required for microcrack nucleation and growth are unrealisticly high, the resulting microcracks are also too short. Simulations show that when grain boundary sliding is allowed, a defect originating at the triple point grows stably, reaches a critical length and then propagates unstably to the neighboring triple point. The stress causing microcrack growth is found to be inversely proportional to the square root of the grain size.
- OSTI ID:
- 175215
- Report Number(s):
- CONF-950686--
- Country of Publication:
- United States
- Language:
- English
Similar Records
Mechanisms of crack nucleation in ice
Grain boundary sliding and stress concentration during creep