Small-scale behavior of natural materials

Richard P. Vinci, Richard Chromik, Jon Zeszotarski, Marie Messmer, and David Cundall

Department of Materials Science and Engineering, Lehigh University


Natural materials (geological or biological) are often difficult to characterize mechanically, either because the features are very small or the substance is not compatible with standardized tests designed for engineering materials.

The behavior of kerogen in shale is one example of a scale-limited system. Understanding the stresses exerted on kerogen is important for the evaluation of potentially oil-bearing rock. Chemically extracting the kerogen from the rock alters its structure and therefore its mechanical properties. Nanoindentation is one method for exploring the properties while the kerogen is still embedded in the substrate.

At a much larger scale, the intermandibular tissue of macrophagic snakes displays remarkable viscoelastic properties. They are also difficult to test because in-vivo testing of poisonous snakes has certain hazards associated with it. Nonetheless, it can be done and the material can be described using classic models from the polymer science community.

Sample Images

nanoindentation curves

Nanoindentation curves resulting from pockets of kerogen and the surrounding shale. Large differences in hardness can be seen from the differences in maximum depth.


Image of in-vivo testing of intermandicular tissue in a Texas rat snake.



Related Publications

  1. J. Zezotarsky, R.R. Chromik, R.P. Vinci, M.C. Messmer, R. Michels, and J.W. Larsen, Imaging and mechanical property measurements of kerogen via nanoindentation, Geochimica et Cosmochimica Acta 68, 2004, p. 4113.

Funding for this work would be welcomed. Support thus far has come from:

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Last updated: August 2, 2005