Abstract
We studied the generation and extension of micro cracks during
semi-brittle failure of rectangular prisms (12 mm x 6 mm x 6 mm) of
Carrara marble under uniaxial compression (i.e., with no confining
pressure) at temperatures ranging from 25 to 184 °C and compared
these observations to existing damage models. Using a long distance
microscope, we generated a series of sequential images of micro-scale
grid made of square markers with sides about 7.5 mm long and spacing of
12.6 mm. The grid covered a region of 1 mm x 0.8 mm near the center of
one free surface. By measuring the relative displacements of the grid
markers, we generated 2 - D finite strain distribution maps at each
stage of the experiment. Deformation was concentrated along cracks. To
study and quantify their evolution additional filtering stage was
applied. At 105 °C and 184 °C, the number and length of micro
cracks increased with increasing load, and near the peak stress, they
intersected and coalesced. By measuring the number and vertical
dimension of the cracks intersecting the surface, we calculated a damage
parameter as defined by Ashby and Sammis [1990]. In the two experiments
mentioned above, the damage sustained by the samples near the peak
stress was much larger than that calculated from the model. In a third
experiment at room temperature, failure was very abrupt and no micro
cracks were observed within the region analyzed.
Original language | English |
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Title of host publication | American Geophysical Union, Fall Meeting 2014 |
State | Published - 2014 |
Externally published | Yes |
Keywords
- 5112 Microstructure
- 5120 Plasticity
- diffusion
- and creep
- 8031 Rheology: crust and lithosphere
- 8118 Dynamics and mechanics of faulting