Plastic Deformation

· The Tresca yield surface has the form of a hexagonal prism centered on the hydrostatic line in principal stress space.
· The diagram shows the effect of both tensile and compressive stresses.
· Inside this hexagonal prism the stress states correspond to the elastic response range of the material.
· On the surface of the prism, the material has reached a stress condition at which yielding can occur.
· Outside the prism, the material will plastically deform.