Applied Mechanics and Materials Vols. 752-753

Abstract: A bone tissue is modeled at the nanolevel as a composite with a quasiperiodic structure, consisting of the hydroxyapatite crystals, which are embedded into the collagen fibrils. The aim of the research is to analyze the influence of the bone nanostructure on its mechanical and strength properties. Such studies are important for the creating artificial bone-substitute materials. The influence analysis of the morphological characteristics (hydroxyapatite crystals disorientation, sizes and orientation of mineral bridges, shape of hydroxyapatite crystals, mineralization) on the local stress-strain state and mechanical properties of the representative volume element of bone is carried out by means of the direct finite element simulation and homogenization. The comparison of the obtained results with experimental data demonstrates a good agreement.

Abstract: Commercial magnesia partially stabilized zirconia (MgO-PSZ) has been selected as the starting materials. Different sintering temperatures have been investigated to determine the optimal conditions. The sintering behavior and characteristic of MgO-PSZ are investigated in this work. Microstructures have been obviously affected by different sintering temperatures. According to dilatometer curve, sintering curve and the shrinkage ratio of sintering process have been estimated. The obtained microstructures have been characterized by scanning electron microscope (SEM).

Abstract: This paper reported the production of precursor PAN/MnO₂ nanofibers via electrospinning method and studying its microstructural properties. The nanofibers were prepared by electrospun the polymer solution of polyacrylonitrile (PAN) and Manganese Oxide (MnO₂) in, N, N-Dimethylformamide as its solvent. The factors considered in this study were polymer PAN/ MnO₂ concentration which will significantly affect the specific surface area, nanofibers morphology, micropore volume and diameter of the nanofibers. The nanofibers were characterized using Scanning Electron Microscopy (SEM), Brunauer Emmett and Teller (BET) surface area, and Fourier Transmission Infrared Spectroscopy (FTIR). The addition of MnO₂ in polymer solution increased the specific surface area of the nanofibers up to 3.5 wt % which found to be its optimum loading. In conclusion, the precursor PAN/ MnO₂ -based ACNF were successfully produced with the optimization of metal oxide loading resulting to nanofibers with higher specific surface area which will further increased its adsorption performance.

Abstract: Stress-strain properties with mini specimen and micro structure of nuclear fuel elements cladding of Al-alloy (98% Al + 1% Fe + 1% Ni) after tempered at temperatures (100-650) °C, for 1 hour have been studied. Al-alloy (98% Al + 1% Fe + 1% Ni) was made for cladding nuclear fuel elements of research reactor. Al-alloy (98% Al + 1% Fe + 1% Ni) as cladding material has been on the rollers and then made a mini specimen tensile test samples. The mini specimen tensile test samples were tempered at temperatures of (100-650) °C, respectively 1 hour. Samples were tested to determine properties of tensile stress-strain with a mini-tensile test specimen. The tensile test equipment can attract maximum sample 5 kN, Shimadzu Autograph AGS-brand artificial 5kN, made in Japan. Then the samples were broken section micro structure observed by SEM (Scanning Electron Microscope). Quantitative results showed that the higher the tempering temperature, the maximum stress is decreased. The higher the tempering temperature cleavage fracture increasingly overlaps (small). This is due to the self-diffusion of Al atoms in the material when the sample tempered at (100-650) °C, for 1 hour. Observation of the microstructure by SEM (Scanning Electron Microscope) was visible presence of porosity in the sample.

Abstract: In this work, finite element calculations were carried out to simulate wire pullout process of the shape memory alloy (SMA) wire/carbon fiber reinforced polymer (CFRP) hybrid composite. Three-dimensional cohesive zone model was used for the bonding interface between the SMA and the CFRP. Phase transformation behavior of the SMA wire was accounted for by using a multi-variant constitutive model. The numerical parameters were fitted using an experimental measurement reported by Jang and Kishi. Young’s modulus of the wire affected the force vs. elongation curve most effectively. It is shown that the actual shear stress profile is not constant but it varies significantly along the axial direction of the wire. Additional toughness due to the SMA wire was higher than the case of a purely elastic wire, and the toughness increment was approximately 21 kJ/m². This value is comparable to the typical toughness value of CFRP.

Abstract: The submitted paper compares mechanical properties of the hard surface layer of modified PBT filled by 35% of glass fibers. Hard surface layer was made by radiation cross-linking technology which allows polymer materials modification followed by the change of their end-use properties. The surface layer of polymer material is modified by β – radiation. When the polymer material is exposed to the β – radiation, it is possible to observe changes of the surface layer at applied load. The mechanical properties were measured by nanohardness test with using the DSI method (Depth Sensing Indentation).

Abstract: The presented article deals with influence of mechanical properties of the hard surface layer of modified polyamide 6. The mechanical properties were acquired by nanohardness test with using the DSI method (Depth Sensing Indentation). Hard surface layer was created by radiation cross-linking technology. This technology allows polymer materials modification followed by the change of their end-use properties. The surface layer of polymer material is modified by β - radiation. When the polymer material is exposed to the β radiation, it is possible to observe changes of the surface layer at applied load.

Abstract: This study was conducted in order to determine the suitable formula in developing a nanofiltration membrane using additive from kenaf core. Kenaf core was processed and analyse the suitable component to be used as the additive in formulation the nanofiltration membrane. Kenaf taken from National Kenaf and Tobacco Board (NKTB) Malaysia with code reference of V36 was used in this study. Cellulose of Kenaf core was extracted using Microcrystalline Cellulose (MCC) process at the Forestry Research Institute of Malaysia (FRIM). From few percentage of Kenaf cellulose with analyses using Flux Purewater Test, NaCl Test (Rejection Test), Molecular Weight Cut Off (MWCO) Test, Scanning Electron Microscopy (SEM) and Fourier Transform Infra Red (FTIR), the suitable percentage of Kenaf cellulose for nanofiltration flat sheet membrane was obtained.

Abstract: Calcium carbonate nanoparticles and nanorods were synthesized by precipitation from saturated sodium carbonate and calcium nitrate aqueous solutions through co precipitation method. A new rout of synthesis was done by both using pulsed mixing method and controlling the addition of calcium nitrate. The effect of the agitation speed, and the temperature on particle size and morphology were investigated. Particles were characterized using X-ray Microanalysis, X-ray analysis (XRD) and scanning electron microscopy (SEM). The results indicated that increasing the mixer rotation speed from 3425 to 15900 (rpm) decreases the average particle size to 64±7 nm. A rapid nucleation then aggregation induced by excessive shear force phenomena could explain this observation. Moreover, by increasing the reaction temperature, the products were converted from nanoparticle to nanorods. The maximum attainable aspect ratio was 6.23 at temperature of 75°C and rotation speed of 3425. Generally, temperature raise promoted a significant homoepitaxial growth in one direction toward the formation of calcite nanorods. Overall, this study can open new avenues to control the morphology of the calcium carbonate nanostructures.

Abstract: This paper presents results of the formation of high aspect nanostructures by local deposition of carbon, stimulated by focused ion beam (FIB). The structures used in the modification of the probe sensors were cantilevers for atomic force microscopy (AFM). The FIB structure of 5 mm length and 50 mm radius of curvature formed on the surface of the cantilever tip has shown to improve the accuracy of measurement by AFM. The outcome of this study is useful for the development of manufacturing processes and modification of the probe sensor-cantilever AFM structures of field-electron emitters as well as in the studies of micro- and nanosystems technology.