The objective of this research is to analyze the fracture toughness of pure and silica co-doped yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) bioceramics containing 0.1 and 0.2 wt.% of alumina, and sintered at a temperature of 1500 °C. Because of the relatively easy preparation of the test specimens and the high speed of testing, the Vickers indentation fracture (VIF) technique is more frequently used to evaluate the fracture toughness of biomaterials and hard biological tissues. The Young's modulus and hardness values were obtained by means of nanoindentation and indentation methods. The fracture toughness values of 3Y-TZP bioceramics were calculated and analyzed using 15 equations related to the VIF technique, and loadings of 49.03 and 196.13 N with a Vickers diamond. For validation, the results were compared with fracture toughness values obtained by the single-edge laser-notch beam (SELNB) method with an almost atomically sharp laser-machined initial notch.

In this research, some mechanical properties of Al 2 O 3-based composites containing nanoSiC and nanoMgO additives, including elasticity modulus, hardness, and fracture toughness, have been evaluated. Micron-sized Al 2 O 3 powders containing 0.08 wt.% nanoMgO particles have been mixed with different volume fractions of nanoSiC particles (2.5 to 15 vol.%). Untreated samples have been sintered by using hot-press technique at temperatures of 1600 to 1750°C. The results show significant increases in the mechanical characteristics with increases in the sintering temperature and amount of nanoSiC particles, with the result that the elasticity modulus, hardness, and fracture toughness were obtained as 426 GPa, 21 GPa, and 4.5 MPa.m 1/2 , respectively.

Link-to-column connections in steel eccentrically braced frames must sustain large moments and shear forces to support link rotation. Recent studies showed that link-to-column connections are prone to failure at low drift levels due to their susceptibility to fracture at the link flange-to-column connections. The most promising method to overcome this problem is to utilize reduced beam section in link, in order to keep away stress concentration from the link ends. In this investigation, the application of reduced beam section in long link beams is studied experimentally. Two full-scale specimens with different reduced beam section locations are constructed and tested under cyclic loading. In one specimen, reduced beam section is placed at both ends of the link beam; and in the other specimen, reduced beam section is solely placed at the link end which is near the column. The results show that both specimens have satisfied the seismic code requirements for the link inelastic rotation, which in turn leads to improvement in seismic performance.