ABSTRACT
Similar to the theory of elasticity, the theory of plasticity was founded on bold assumptions based on observations of experiments followed with idealizations and simpli—cations. The early experiments of Tresca (1870) in the 1860s established the concept that large plastic deformation is shear deformation governed primarily by shear stress. It took a great insight to ignore the time effects to start the mathematical theory of plasticity. The choice of maximum shear stress as the critical shear stress for the Tresca yield criterion for metallic material started the development of the theory of metal plasticity. Similarly, the choice of a normal-stressdependent maximum shear stress as a failure criterion for granular media laid the foundation of Coulomb’s (1773) failure criterion, proposed much earlier for soils, for the subsequent development of the lateral earth pressure theory in 1776 by the French physicist Charles-Augustin de Coulomb who began the modern theory of soil mechanics.
