Relationship between Lode parameter and deformation type

In order to study inherent relation of strain parameters in depth, the relation between different strain increments and Lode parameter was formulated, hence the quantitative relation between strain increments was given directly. The deformation type and the Lode parameter were connected with each other directly. Therefore, the inherent relationship between the deformation type and stress status was discovered. The results indicate that the scope of elongation deformation zone narrows with the increasing of height-to-diameter ratio in annulus compression, the deformation types of the metal in the plastic deformation area change from a single type of elongation to three types of deformation, i.e., elongation plane strain compression, with the increasing of die angle in extrusion. As a result, the homogeneity of metal flow decreased obviously. This research is of great significance to the plastic theory and its application.