@article{MardoukhiMardoukhiHokkaetal.2020,
  author    = {Mardoukhi, Ahmad and Mardoukhi, Yousof and Hokka, Mikko and Kuokkala, Veli-Tapani},
  title     = {Effects of test temperature and low temperature thermal cycling on the dynamic tensile strength of granitic rocks},
  series = {Rock mechanics and rock engineering},
  volume    = {54},
  journal   = {Rock mechanics and rock engineering},
  number    = {1},
  publisher = {Springer},
  address   = {Wien},
  issn      = {0723-2632},
  doi       = {10.1007/s00603-020-02253-6},
  pages     = {443 -- 454},
  year      = {2020},
  abstract  = {This paper presents an experimental procedure for the characterization of the granitic rocks on a Mars-like environment. To gain a better understanding of the drilling conditions on Mars, the dynamic tensile behavior of the two granitic rocks was studied using the Brazilian disc test and a Split Hopkinson Pressure Bar. The room temperature tests were performed on the specimens, which had gone through thermal cycling between room temperature and - 70 degrees C for 0, 10, 15, and 20 cycles. In addition, the high strain rate Brazilian disc tests were carried out on the samples without the thermal cyclic loading at test temperatures of - 30 degrees C, - 50 degrees C, and - 70 degrees C. Microscopy results show that the rocks with different microstructures respond differently to cyclic thermal loading. However, decreasing the test temperature leads to an increasing in the tensile strength of both studied rocks, and the softening of the rocks is observed for both rocks as the temperature reaches - 70 degrees C. This paper presents a quantitative assessment of the effects of the thermal cyclic loading and temperature on the mechanical behavior of studied rocks in the Mars-like environment. The results of this work will bring new insight into the mechanical response of rock material in extreme environments.},
  language  = {en}
}
@article{MardoukhiMardoukhiHokkaetal.2017,
  author    = {Mardoukhi, Ahmad and Mardoukhi, Yousof and Hokka, Mikko and Kuokkala, Veli-Tapani},
  title     = {Effects of strain rate and surface cracks on the mechanical behaviour of Balmoral Red granite},
  series = {Philosophical Transactions of the Royal Society of London, Series A : Mathematical, Physical and Engineering Sciences},
  volume    = {375},
  journal   = {Philosophical Transactions of the Royal Society of London, Series A : Mathematical, Physical and Engineering Sciences},
  number    = {2085},
  publisher = {Royal Society},
  address   = {London},
  issn      = {1364-503X},
  doi       = {10.1098/rsta.2016.0179},
  pages     = {11},
  year      = {2017},
  abstract  = {This work presents a systematic study on the effects of strain rate and surface cracks on the mechanical properties and behaviour of Balmoral Red granite. The tensile behaviour of the rock was studied at low and high strain rates using Brazilian disc samples. Heat shocks were used to produce samples with different amounts of surface cracks. The surface crack patterns were analysed using optical microscopy, and the complexity of the patterns was quantified by calculating the fractal dimensions of the patterns. The strength of the rock clearly drops as a function of increasing fractal dimensions in the studied strain rate range. However, the dynamic strength of the rock drops significantly faster than the quasi-static strength, and, because of this, also the strain rate sensitivity of the rock decreases with increasing fractal dimensions. This can be explained by the fracture behaviour and fragmentation during the dynamic loading, which is more strongly affected by the heat shock than the fragmentation at low strain rates.},
  language  = {en}
}