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We have attempted to observe straining responses of an individual multi-walled carbon nanotube (MWNT) by performing an in-situ tensile testing inside scanning electron microscope (SEM). The both ends of an individual MWNT was attached on the rigid support and the tip of the force sensor using electron beam and was elongated by a nano-manipulator. The nano-manipulator was automatically controlled by personal computer. Linear deformation and fracture behaviors of MWNT were successfully observed and its force-displacement curve was also measured from the bending stiffness and displacement of the force sensor and manipulator. The tensile properties of individual MWNT were evaluated from the tensile test results.

Nanoindentation test has been performed to characterize the mechanical properties of aluminium alloy foam cell wall. Two of the mechanical properties: hardness and Young’s modulus of cell wall material were evaluated using the stiffness of contact during both loading and unloading. Properties obtained from unloading stiffness were in better agreement with the conventional test result than those obtained from loading stiffness. The finite element analysis using nonlinear finite element code ABAQUS was performed to characterize the yield strength and the stress-strain curve of the cell wall material of the foam. Properties of foam cell wall material were found to be substantially different from the properties of the material before foaming. The methodology used in this paper can be effectively used to characterize the mechanical properties of cell wall of any cellular material.

More effective nondestructive technology for the estimation on material properties has been sought. In this research, a new electrical resistivity method was attempted for the estimation of the creep damage of a degraded heater tube steel. HK40 steel specimens with five different periods of aging were prepared by an isothermal heat treatment at 1050°C and the electrical resistivity was determined by a standard DC four-point probe method. The electrical resistivity at room temperature monotonously decreased with the extent of degradation of the material. It was also observed that Vickers hardness was correlated with the electrical resistivity. The microstructural changes of material during aging was examined by microscope.

Since fracture surface presents clear evidence to describe the circumstances of material failure event, analysis of fracture surface should provide plenty of useful information for failure prevention. Thus if we extract proper information from the fracture surface, the safety evaluation for plant component could be more accurate. In general, the chaotic morphology of fracture surface is determined by the degree of material degradation as well as by other factors such as type of load, geometry of specimen, notch condition, microstructure of material and environment. In this research, we developed a fractal analysis technology for the fracture surface of aged turbine rotor steel based on the slit-island technique using an image analyzer. Moreover the correlation between the fractal dimension and the aging time was studied.

The fracture toughness of polycrystalline ceramics used to present the scale effect as well as statistical distribution. It is believed that both (scale effect and scatter) must be associated with the heterogeneity of materials. However, no generally accepted theory has been established so far. Using statistical approach, a probabilistic modelling for the fracture toughness which describes the scale effect was attempted in this paper. Weibull distribution of specific fracture energy (SFE) at local area and Griffith criterion are jointly applied to the model. Finally, the fracture toughness scale dependence of ASTM E399 standard specimens was investigated by the newly developed model.