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ABSTRACT Structural performance of steel-concrete composite structures relies deeply on the characteristics of the shear connectors. Recently, great attention has been focused on the implementation of C-shaped connectors due to [...]

Commercially pure titanium (CP-Ti) has been recently used as metallic biomaterials due to excellent biocompatibility and specific strength. CP-Ti has less static and dynamic strength as compared to other metallic biomaterials. Processing by the equal channel angular pressing (ECAP) as one of the most effective severe plastic deformation (SPD) method could lead to an increase in the mechanical strength of materials, significantly. In this study, Grade 2 CP-Ti billet is inserted into Al-7075 casing, and is then deformed by ECAP, with the channel angle of 1358, through 3 passes at route BCand room temperature. The purpose of using casing is to attain higher deformation homogeneity and more material ductility in the billet. The microstructural analysis shows that the coarse grain (CG) CP-Ti is developed to ultrafine grain (UFG) structures after ECAP. In order to investigate the static and dynamic strength of CG and UFG CP-Ti, the tensile and axial fatigue tests are conducted. The results represent that UFG CP-Ti has much more tensile and fatigue strength than CG CP-Ti, and it could be utilized as biomaterials for production of implants. Surface features of fatigue fracture are also investigated. It should be noted that the investigation of fatigue strength of UFG CP-Ti produced by ECAP at RT utilizing casing, has not been conducted so far.

In this paper, the effects of the length, sector angle and boundary conditions on the buckling load and post-buckling behaviour of cylindrical panels have been studied, experimentally. The compressive axial load has been applied on the panels using servo-hydraulic machine and different boundary conditions have been prepared by suitable fixtures. The presented results can be used in designing of these structures.

Abstract: In this study, carotenoid and glycerol production in two unicellular green algae (Dunaliella salina and D. viridis) isolated from the Gave-Khooni salt marsh grown in media containing five different salt concentrations (0.17, 1, 2, 3, and 4 M NaCl) were evaluated under sterile conditions. Algae growth decreased as the medium salinity increased. Optimum growth of D. salina and D. viridis were obtained at 2 and 1 M NaCl, respectively. As salinity increased, glycerol and carotenoid production were increased in D. salina, whereas lower values for these products were produced in D. viridis under the same conditions. Furthermore, the cell color of D. salina changed from green to orange-red following accumulation of carotenoid, but the color of D. viridis was not changed. Thereby, it seems that the Iranian D. salina may be suitable for carotenoid production (betacarotene) on a large scale. In addition, since carotenoid compounds enhance the efficiency of photosynthesis and glycerol synthesis, it appears that the pathway for glycerol production and mechanisms of salt tolerance in D. viridis are unique from those of D. salina.

This paper investigates ratcheting behavior of SS316 L thin-walled steel pipes subjected to cyclic internal pressure experimentally and numerically. Numerical simulations were performed using abaqus software, and nonlinear isotropic/kinematic hardening model. According to experimentations, it was found that the ratcheting strain is only significant in the hoop direction of a pipe subjected to cyclic internal pressure. The effects of pressure amplitude and mean pressure on ratcheting behavior of thin walled pipe in hoop direction were studied experimentally and numerically, and it was observed that increasing the pressure amplitude and mean pressure increased the percentage of ratcheting strain. Another important point about the results was the dominance of pressure amplitude on mean pressure. The results showed that at higher mean pressures the effect of pressure amplitude on increasing the percentage of ratcheting strain was greater. Finally, the experimental and numerical results were in good agreement.