The initial configuration is a new (or well–forgotten old) variable in mechanics; its application in problems of thermoelasticity, masselasticity, plasticity and others

The initial (or more strictly unloaded) configuration of a deformable body is an equal independent variable in problems of mechanics, along with such variables as the radius vector and velocity of a material point, temperature or concentration. The initial configuration remains unchanged under elastic deformation of the medium, but begins to change and play a decisive role in problems of thermoelasticity or masselasticity. The initial configuration changes irreversibly with the plastic flow of the material. It is shown that the explicit introduction of the initial configuration as an independent variable in the formulation of the problem provides a number of advantages in modeling. Examples are given.