Stress space

This space is named after Bernard Haigh and Harold M. Westergaard.

In mathematical terms, H-W space can also be interpreted (understood) as a set of numerical markers of stress tensors orbits (with respect to proper rotations group – special orthogonal group SO3); every point of H-W space represents one orbit.

[1] Functions of the principal stresses, such as the yield function, can be represented by surfaces in 'stress space.

In particular, the surface represented by von Mises yield function is a right circular cylinder, equiaxial to each of the three stress axes.

In 2-dimensional models, stress space reduces to a plane and the von Mises yield surface reduces to an ellipse.