ABSTRACT
This chapter begins by analysing complex stress systems using stress elements. It focuses on complex strain, including volumetric strain and the relationship of strain to the elastic constants and Poisson's ratio. Engineering materials and structures are generally subject to a combination of loading situations that set up a complex network of stresses and strains within the material. Graphical methods are recommended for their simplicity and ease with which the principal stresses may be found. Two graphical methods are commonly used, the McClintock method and Mohr's superimposition method, where a stress circle is superimposed onto a strain circle. Note that zero strain in the z direction does not necessarily mean that there is zero stress in this direction. From the Poisson effect, there will also need to be a stress in the z direction that prevents the occurrence of this strain. The stress element ABCD is subject to pure shear by the stresses and complementary stresses.
