The blunt tip geometry of the so-called nanoindenter is modeled by a spherical cap of various radii. The relation between area and penetration depth of the indenter is comparable with experimental results if the radius of the tip is about 1.0 μm. Simulation of indentation tests was carried out using the finite element method by incremental loading and unloading based on a continuum model. Good agreement with the experimental results for nickel is obtained also for a tip radius of 1.0 μm.

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The photoelastic stress-freezing technique is applied to observe the stress distribution inside two spheres of different sizes compressed together elastically. After the stress is frozen in, thin slices of the material containing the symmetry axis are prepared for observation through a polariscope. The stress distribution is compared with both the finite element numerical analysis and the Hertz analytical theory which is limited to small deformations. Among the three, the agreement between the experimental results and the finite element analysis is the best. The deviation from the Hertz theory is less in the larger sphere contacting a smaller one than in the smaller sphere contacting a larger one.

Because bolt usages always have the requirement of tensile strength, with a view to reach the requirement of tensile strength, the material property or forming method and dies design can be used to obtain it. The study aims at the forming method and dies design to perform the multistage analysis of bolt to realize the effect of forging stream line continuity on tensile strength. The study uses Simufact-FEM software to do the multistage forming simulation to modify the dies design and forming method. The amount of broken forging stream line can be used to identify whether the bolt is good or not. From the comparison of realistic forging product, the results can verify the acceptance of FEM simulation.

This study aims at analyzing the influence of the maximum principal stress on Tungsten Carbide Steel die core in an extrusion die which caused the crack of die core, and then adjusts the dies assembly method in order to improve the service life of die. In this study, we combine FEM simulation software with the Taguchi Method L9(34) to choose the cobalt content for die core materials, and the quantity of shrink fit while assembling the die core and die case as the reference parameters. When carrying out the simulation process, we compared the changes of the maximum principal stress of the die core caused by the plastic deformation of die materials to achieve the minimum expected value as the goal for the most optimal die combination. Then, the results obtained are to make dies in trial and mass-production practically; as a result, the die life is improved from the original 1000 to 150,000 pcs, which is more than 150 times better than before.