An effective process of strain measurement for severe and localized plastic deformation

Large deformation is a major deformation operation in many metal-forming processes, such as forging, rolling, extrusion, stamping and fine-blanking. It is difficult to study the deformation changes in these processes in a practical way, through the measurement of strains, due to the severe and localized nature of plastic deformation such as in the fine-blanking operation, where only about 30% of the punch penetration through the thickness of the material can be measured through experiment. Therefore, the large strain analysis of most metal-forming processes cannot be carried out successfully by experiments. Thus, this paper aims to present the development of an effective process of strain measurement for severe and localized plastic deformation. To validate the process, an experimental remeshing technique was adopted and applied on a tension test to measure strains in practice. As a result, it was found that, on average, only a 10% difference in effective strains was observed between the experimental findings with and without remeshing. Meanwhile, the developed process was further applied to the fine-blanking operation. Results show that the strain measurement for fine-blanking was accurate. As a conclusion, the process of experimental remeshing presented in this paper can be effectively used to measure strains in severe and localized plastic deformations.