MECHANICAL HYSTERESIS,

Mechanical hysteresis loops have been obtained from a plot of the dynamic stress-strain characteristics of a material. The loops depict an assymmetric figure 8 pattern, for which the assymmetry is accounted for by the non-uniform elastic state of the material. Supplementary experiments demonstrating the complex motion of particles in a longitudinally excited vibrator, lead to the conclusion that the paths traced by electrons in the lattice structure is dif ferent for the tensile and compressive portions of the cycle. Since the potential field in the lattice structure is non-uniform, a hysteresis los-s observed. The lateral motion of a longitudinally excited vibrator is shown to produce shearing strains, which are a dominant factor in internal friction. Illustrations of the effect of the shape of the hysteresis loop on fatigue are given. Author