Plasticity

An aeronautical structure is sized under the ultimate loads (UL), while accounting for the plasticity. This chapter notes a plastic strain localization phenomenon which starts at the maximum stress point and which is called necking, by observing the shape of the sample in a tension test. It shows that the stress state in the necking area is no longer a pure tension state, but a tri-axial stress state. In order to model a test which makes plasticity appear, it is necessary to adapt the elastic behavior law. To do so, the chapter assumes that the strain can be seen as a sum of elastic strain and of plastic strain. In order to illustrate the use of accounting for the plasticity in the structure calculation, the example of a holed plate in tension is studied.