Characterization of Mechanical Properties of a Synthetic Modeling Clay Used as a Substitute for Natural Soils

This paper discusses the use of Crayola modeling clay as a substitute for natural soil. This product is relatively inexpensive, non-drying, reusable, pliable, and commercially available. The unconfined compression test was performed to determine mechanical properties. Additionally, inverse analysis was implemented to characterize the elastoplastic response. The model used in the inverse analysis considers finite deformation plasticity. The stress-strain relationship was obtained by defining a local dissipation function and using the principle of maximum dissipation. The formulation is based on hyperelasticity and expressed in terms of Kirchhoff stress, logarithmic strain, and the multiplicative decomposition of deformation gradient to overcome the limitations of the theory based on infinitesimal deformation. The hardening behavior is prescribed based on Ludwik's equation. Inverse analysis is performed using a genetic algorithm to minimize the difference between the experimental data and predicted results for the unconfined compression tests.