Plastic Rigid Solid with Linear Strain Hardening
The model plastic, rigid solid with linear strain hardening material behaviour presents two different parts. First, for the initial part of the curve, the behaviour is rigid, therefore deformations are null until yield stress σ0 is reached. Stains generated above yield stress are always plastic (permanent) and proportional to the difference between current stress and yield stress.
The mechanical model describing this behaviour is a parallel configuration connection of a linear spring with constant E and a friction plane with constant σ0. Strain levels reached by both elements with this configuration remain the same, while load (stress) applied to the system is distributed between both elements. If the stress is under reference σ0,, then, the friction plane will support all the load with null deformation. Once yield stress is reached, the load on the friction plane remains σ0, while a deformation proportional to the load on the spring (σ - σ0) is generated. When it is always plastic, the strain generated remains permanent.