Bulk Modulus of Isotropic Materials. Consider a material block under a hydrostatic pressure, p, as show in Figure 1. If the block is made of an isotropic linear-elastic material, show that the trace of the strain tensor e = ii, which is also called the volumetric strain, is related to the pressure by where K is the bulk modulus of the material given by E 3(1-2v)* P p = Ke, 12 K= = lx FIGURE 1. Hydrostatic loading. ly