Investigation on mechanism of plastic deformation by digital speckle pattern interferometry

An experimental scheme of digital speckle pattern interferometry using two electromagnetic shutters and a three-frame color image board is presented to measure two in-plane components of incremental displacement field of diffuse objects. The deformation of the entire process from initial elastic deformation to fracture can be observed by using a Magneto Optical (MO) disk that has enough memory to record the image data of the entire process. By this system, some tensile experiments are achieved to investigate the mechanism of plastic deformation. The experimental results show that plastic deformation of tensile deformation is; nonuniform. The material deforms in the distribution of domains. in the domains, the main deformation is uniform shear and rotation. At the boundary of the domains, the deformation is very lame normal strain. With load, both the range and mode of domains are changing. At the end of plastic deformation, only two domains become dominant, and fracture happens at the boundary of the two domains.