As compared to other optical glasses, when fused silica (Si02) is ground or polished, it has some unique features, such as low surface microroughness and subsurface damage, low grinding-induced residual stresses, and low removal rates. It also has higher hardness. On the other hand, fused silica's Young's modulus and fracture toughness are in the middle range of the optical glasses. So, compared to other optical glasses, fused silica behaves differently under compressive loads. When subjected to sufficiently large compressive stresses, fused silica glass will densify permanently. It is also noticed that shear will facilitate densification. We model this behavior by a simple constitutive law including both shear flow and densification.The constitutive model was used to interpret nanoindentation tests on fused silica via 3D finite element simulations of indentations of Berkovich indenter. This work extends our previous work on axisymmetric (2D) indentation.

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In order to study the micromechanical behaviour of the forged Ti-1023 titanium alloy, micro-indentation experiments of the forged Ti-1023 titanium alloy were performed with various maximum indentation loads from 500 mN to 4000 mN and various loading speeds from 5.06 mN/s to 51.85 mN/s. Using the experimental data, the non-destructive instrumental approach was applied to indicate the mechanical properties just like the Young’s modulusE, microhardnessH, initial yield stressσyand strain hardening exponentnusing theP-hcurves from the tests. The result showed that the value of the indentation Young’s modulus basically remain unchanged in the range from 110 GPa to 150 GPa andHdecreased with the increase of the load, the micro-indentaion plasticity constitutive equations were obtained by using Hookean elastic and power-law plastic stress-strain equations.