Inhomogeneous Plastic Deformation and Change in Surface Profile of Metals and Polymers

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The present study consists of experimental and analytical studies of inhomogeneous deformation and change in surface shape of metals and polymers. The stylus instrument for surface roughness measurement and the scanning electron microscop was used in the experiment, while numerical simulation based on the finite element method and models of inhomogeneous material was employed.Iron specimen were used to study the relation between surface roughness and deformation of grains in polycrystals. The image processing technique was also incorporated in the measurement of microscopic inhomogeneous deformation. Brass specimens composed of alpha-phase and beta-phase were also used to study the mechanism of deformation of two-phase metal. Various commercial polymers were used to study the surface roughening during plastic deformation. The change in surface morphology was also studied by the scanning electron microscope, where the ion-coater instrument was used to put the gold coating film on the polymer specimens. It was found that the surface roughening occurs on the surface of the crystalline polymers, while no surface roughening was observed on the amorphous polymers.Numerical simulation of surface roughening during large plastic deformation of inhomogeneous material was performed with the finite strain version of the elastic-plastic unite element method. The effects of the material inhomogeneity and the surface instability were discussed based on the calculated results. The inhomogeneous deformation of rubber compound was also simulated based on the Mooney-Rivlin constitutive law.