IMPACT OF INDENTOR SLIDING VELOCITY AND LOADING REPETITION FACTOR ON SHEAR STRAIN AND STRUCTURE DISPERSION IN NANOSTRUCTURING BURNISHING

The article probes into a relationship of the shear strain intensity and the shear strain rate in the surface layer and the sliding velocity of a spherical indentor and its loading repetition factor. It brings forward an experimental procedure to evaluate the shear strain intensity and rate by analyzing the geometrical parameters of the bulge of plastically edged metal and the thickness of the shifted layer relative to different sliding velocities and feed rates.

Indentation of a transversely loaded functionally graded rectangular plate by a rigid spherical indentor

Functionally graded materials are multiphase composites mainly composed of a ceramic and a metal; thus, they merge the heat, oxidation and corrosion resistance typical of ceramics, and the strength, ductility and toughness typical of metals. Many of the present and possible applications of functionally graded materials involve contact loading. Here, the contact problem of a functionally graded simply supported plate with finite dimensions by a rigid spherical punch is studied by an analytical–numerical method. The contact rule will be derived by solving the equations of equilibrium analytically in terms of the displacement field components and by taking advantage of a numerical method in finding the contact parameters. The stress–strain relation is assumed to be linear and is represented by a refined volume fraction based model originally proposed by Tamura–Tomota–Ozawa model. The results of the analytical–numerical approach are validated by using ABAQUS finite element package. The analytical–numerical results are used to investigate the effect of parameters such as material distribution, punch radius, plate span and thickness on the contact rule and stress distribution in the plate. The obtained results show that the influence of the material non-homogeneity on the contact rule and stress distribution is quite significant. In addition, the acquired results illustrate that increasing the indentor diameter and the thickness of the plate increase the contact force for equal amount of indentation.

Analysis of Dislocations Nucleated after Nano Indentation Tests at Room Temperature in 4H-SiC

4H-SiC intrinsic homoepitaxied single crystals have been nano indented at room temperature using a spherical indentor and the related deformation microstructures have been analyzed by Transmission Electron Microscopy. Dislocations are lying in the basal plane but have been found to be perfect, in contrast with observations made at higher temperature. Although such a change in deformation mechanism has been observed in other semiconductors such as Silicon and Indium Antimonide, it was unexpected in a very low stacking fault material such as SiC.

A Model of Force Transmission in the Tibio-Femoral Contact Incorporating Fluid and Mixtures

An axisymmetric finite element model is formulated which comprises a rigid spherical indentor, a meniscal ring and an articular cartilage layer, both considered as mixture materials which are interacting with an ideal fluid sub-system. From parameter studies it is concluded that the application of the mixture theory in comparison with solid modelling only leads to significant effects when the outer surfaces of the components are not sealed. The load distribution appears to change enormously during relaxation of the models. Initially the largest fraction of the load is borne by the fluid in the cavity, while at the end, when the system has reached its final configuration, the meniscal ring bears the major part of the load. Further, the length of the relaxation period appears to depend on the magnitude of the step change of the load. Finally, the curvature of the spherical indentor appears to have significant effects on the loading of the meniscal ring, only immediately after the step changes of load are applied, and these effects disappear as soon as the fluid starts to exude from the models.