Abstract: The article presents a method of determining the anisotropic friction model in metal forming using multilayer artificial neural networks based on experimental data obtained from the pin-on-disk tribometer. The experimental results show that the friction coefficient depends on the measured angle from the rolling direction and corresponds to the surface topography. Both the friction and material anisotropic models were implemented into a finite element (FE) model built using the commercial FE-package ABAQUS/Standard. When both the material and friction anisotropy are taken into account in the finite element analysis, this approach gives the most approximate numerical results to real processes.
Abstract: Polymers-Surfactant complex efficacy in reducing the drag is of an interest subject in drag reduction research. Turbulent drag reduction (DR) efficiency of Sodium Polystyrene Sulfonate (NaPSS) sodium Alkylbenzene sulfonate complex was studied in a rotating disk apparatus. The solution complex was prepared by varying the concentration of the polymer between 100 to 1200 ppm and the surfactant between 100 to 700ppm. Measurement of torque values were recorded for each sample. The NaPSS (Sodium Polystyrene Sulfante) was found to have an ability to reduce the drag in the turbulent flow. A significant improvement was recorded for the addition of tiny amount of surfactant to the polymer system compare to the pure polymer drag reduction. At high surfactant concentration, it was found that the polymer drag ability decrease. The polymer was degraded when it is subjected to a high shear stress. The degredation resistance was increased by the addation of the surfactant to the polymer solution at concentration range of 100ppm to 400ppm of surfactant.
Abstract: The fatigue property of a TRIP (transformation induced plasticity) steel after resistance spot welding (RSW) is investigated. It is found that the fatigue strength of the spot weld is only 8.9% of the original TRIP800 steel. This is a result of microstructure mismatch in heat affected zone (HAZ) due to different cooling rates during RSW. A maximum variation of about 220HV microhardness is observed at different areas from the relatively narrow HAZ. The fatigue degradation is attributed to the inhomogeneous distributions of microstructure and microhardness at HAZ and its adjacent zones. The fatigue crack initiated between HAZ and BM is a cleavage fracture as confirmed by scanning electron microscopy (SEM) observation.
Abstract: This paper presents an experimental investigation on the influences of EDM parameters on machining time and surface roughness for machining Inconel 800.Inconel800is widely used in construction of equipment that must have high strength and resist carburization, oxidation and other harmful effects of high temperature exposure. The selected WEDM parameters are pulsed current (210,220 and 230A), pulse-on time (2,3.25, 4.5, 5.75, 7 and 8.25μs) and pulse-off time (19 and 46μs). It has been observed that surface roughness increases with the increase of pulse-on time and pulse current. Similarly machining time decreases with the increase of pulse current and pulse-on time. Conversely, a decreased value of pulsed current and pulse-on time results in a better surface finish and increased machining time.
Abstract: In the article, a simple method for the modification of the Stoney's equation was presented. The Stoney's equation is proposed from the assumption of equi-biaxial residual stresses in thin films. In this present method, biaxial stresses are different in x-axis and y-axis on thin film. The location of neutral axis depends on the material parameters and the film thickness. The finite element method (FEM) was used to simulate the thermal stress on the thin film. The results of the modified methods are compared with the results of FEM and other literatures. The present method is more accurate than the Stoney's equation in the evaluation of such films.
Abstract: This work is devoted to investigation of the way light transmittance of drying drop of Fe2O3 nanocolloid deposited on flat surface changes as liquid evaporates. According to results of transmitted light intensity measuring it is assumed that drying process can be divided into separate stages each being characterized by particular quality level of ability to transmit light because of different behavior and, thus, density of suspended nanoparticles inside the droplet. The last stage ends by forming of a ring-shaped pattern (known as “coffee ring”). Temperature of the surface was being changed by applying a varying potential difference to lower layer of transparent substrate made of ITO. Time dependences of integral transmitted light intensity for every single temperature are represented in graphs. They are compared with dependences for water drops of the same volume.
Abstract: Polymer resin grout can be used as bonding material for grouted sleeve connections This paper presents the experimental results on the effectiveness of fly ash as micro filler to the splitting tensile strength of polymer grout. In addition, the cement grout that is usually used as bonding material had been tested for comparison. Eleven proportions, of fly ash as the filler and polymer as binder, were tested with the binder to filler volume ratios of 1:1 and 1:1.5. The test results revealed that fly ash can be used as a micro-filler material to partially replace ordinary river sand in polymer resin grout. The splitting tensile strength of the polymer grout increases with the increase of fly ash contents. However, for higher level of fly ash of more than 22%, the splitting tensile strength deteriorated. For binder: filler ratio of 1:1, the optimum fly ash content of 22% gave the maximum splitting strength of 17.62 MPa, which can be considered acceptable for producing grout with high strength bonding material.
Abstract: A Composite oxide ionic conductor consisting of La10Si6O27 (LASIO) and Ce0.9Gd0.1O1.95 (GDC) was synthesized by a modified sol-gel method. The La10Si6O27 powders prepared by modified sol-gel synthesis were coated with GDC gel and latter calcined to form a La10Si6O27 - Ce0.9Gd0.1O1.95 composite material. The structural and microstructural properties of the composite were investigated using powder XRD, SEM and TMA. EIS was conducted in air on the sintered pellets to evaluate the electrochemical performance of the pellets. The conductivity of the composite electrolyte at 973 K was 26 mS /cm which is two orders of magnitudes higher than that for the pure LASIO but lower than that of the GDC (30 mS/cm). The thermal expansion of the composite electrolyte is similar to that obtained for the LASIO.
Abstract: The polycrystalline ferrites of MgAlxFe2-xO4 (0.0≤x≤0.4) were prepared by the conventional solid state ceramic method. The specimens were sintered at 13500C and X-ray diffraction experiments were done at room temperature which showed single phased cubic spinel structure. The lattice parameters were determined from the XRD data using Nelson-Riley extrapolation method and found to decrease with increasing Al concentration obeying Vegard’s law. The cation distribution and oxygen position parameters have also been determined by refining the data using the RIETAN-2000 in the Rietveld method which reveals that the samples possess cubic symmetry corresponding to the space group Fd-3m. The X-ray density and bulk density of each sample were calculated using the lattice parameters. The porosity has been determined from X-ray density (ρx) and bulk density (ρB) and it changes monotonically with Al content.