Interface energies and structured deformations in plasticity

I discuss the model of an elastic bar with interface energy at the jump points of the displacement function. If the interface energy is convex near the origin, the energy minima are attained by uniform limits of sequences of functions with a number of jumps growing to infinity, while their amplitudes decrease to zero. The limit elements are identified with mathematical objects called structured deformations. The model determines three regimes for the bar, which I call elastic, plastic, and fractured, and is able to describe the phenomenon of elastic unloading.