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 t o measure two in-plane components of incremental displacement field of diff use objects. The deformation of the entire process from initial elastic def ormation to fracture can be observed by using a Magneto Optical (MO) disk t hat has enough memory to record the image data of the entire process. By th is system, some tensile experiments are achieved to investigate the mechani sm of plastic deformation. The experimental results show that plastic defor mation of tensile deformation is; nonuniform. The material deforms in the d istribution of domains. in the domains, the main deformation is uniform she ar and rotation. At the boundary of the domains, the deformation is very la me normal strain. With load, both the range and mode of domains are changin g. At the end of plastic deformation, only two domains become dominant, and fracture happens at the boundary of the two domains.