Localization of Deformation

Even if material is subjected to a homogeneous stress, the deformation concentrates in a quite narrow strip zone as the deformation becomes large and finally the material results in failure. Such a concentration of deformation is called the

localization

of deformation and the

strip zone

is called the shear band. The shear band thickness is the order of several microns in metals and ten and several times of particle diameter in soils. Therefore, a large shear deformation inside the shear band is hardly reflected in the change of external appearance of the whole body, although the stress is determined by the external load and the outer appearance of material. Therefore, a special care is required for the interpretation of element test data and the analysis taking account of the inception of shear band is indispensable when a large deformation is induced. The localization phenomenon of deformation and its pertinent analysis are addressed in this chapter.