Metallurgical and Materials Engineering (E-Journal)
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Dynamic Analyses of Two-Dimensional Functionally Graded Timoshenko Beam using Finite element Method
Get PDFIn this work, dynamic analyses of a functionally graded beam are presented. The governing equations of the beam is found based on the displacement field defined by Timoshenko beam theory, then solved by using finite element method based on Hamilton’s principle. The beam is assumed to be free-clambed boundary condition (F-C). The PL index is used for describing the distribution of the beam properties in both transverse and longitudinal directions. A parametric study is accomplished to investigate effect of several parameters on the natural frequency, mode shapes and transient response of the beam., such as the PL indexes (nx and nz) for x and z axis, respectively, and the elasticity modulus ratio (Eratio). To valid the present results and current mathematical formulation, some of the findings are compared with another research. A good agreement is noticed. It is noted that the response of the beam is more sensitive to the variations of the PI in the longitudinal axes than that corresponding in the transverse one. For specific design requirements, the dynamic response of the beam can be adjusted by chose a proposal indexes and modulus ratios
A Finite Difference Scheme For Solving Partial Differential Equations In Heat Conduction Problems In Mechanical Engineering
Get PDFWhen it comes to mechanical engineering, the majority of thermo physical processes are governed by partial differential equations (PDEs), notably those that are associated with transient and steady-state heat conduction respectively. Due to the fact that analytical solutions are only applicable to issues that have simplified geometries and boundary conditions, finite-difference approximations have emerged as a viable option for obtaining approximate solutions for areas that are more intricate. For the two-dimensional heat conduction problem, the current study presents an ordered finite-difference (FDM) scheme that has been customized to function properly. The approach is excellent for engineering applications because it has numerical stability, consistency, and convergence. It accomplishes these goals by using central difference approximations in space and an implicit backward Euler method in time. In this paper, we offer a rigorous mathematical derivation of the strategy, which is reinforced by stability analysis using the von Neumann methodology. For the purpose of solving typical heat transfer issues, numerical calculations are carried out. These problems include transient heat conduction in a rectangular plate and steady-state distribution in a finned surface. When compared with benchmarked analytical and semi-analytical solutions, comparison analysis reveals root-mean-square errors that are less than 1.5%, which is evidence of the model's impressive level of accuracy. Additionally, the method that was developed is used to simulate actual thermal conditions using experimental datasets that are already in existence. This demonstrates the program's practical applicability in the simulation of component design and production. The findings provide evidence that the approach is robust, computationally efficient, and amenable to use in the context of more complex mechanical systems. The purpose of this effort is to establish a replicable model that is compliant with the existing production requirements for thermal condition-based simulation-driven design
Air and Vacuum Annealing Effect on the Highly Conducting and Transparent Properties of the Undoped Zinc Oxide Thin Films Prepared by DC Magnetron Sputtering
Get PDFIn this study, we aim to investigate the effect of zinc interstitials (Zni) and oxygen vacancies (VO) on the ZnO electrical conductivity. ZnO films were synthesized via DC magnetron sputtering process using pure Zn target in gases mixture of Ar/O2 = 80/17.5 (sccm). In order to improve the optical and electrical prosperities, the obtained films were subjected to air and vacuum annealing treatment. Several techniques such as field emission scanning electron microscopy (FESEM), Grazing Incidence X-ray Diffraction (GIXRD), Raman spectroscopy, photoluminescence spectroscopy (PL) and UV-visible were used to study the influence of heat treatment on structural and physical properties of ZnO films. Electrical conductivity of ZnO thin films was determined by measuring the sheet resistance and thickness of the films. XRD results confirm the synthesis of annealed ZnO films of the hexagonal structure with a preferential orientation along the (002) plane. The average crystallite size is altered between 22.6 to 28.4 nm dependent on the plan orientation of the ZnO film. Morphology and crystallinity of the ZnO structure could efficiently control the transmittance, electrical resistivity and optical band gap. As deposited ZnO film showed a lower electrical resistivity of 2.72×10-3 Ωcm due to the Zn-rich conditions. Under vacuum annealing, a combination of low resistivity (1.17×10-2 Ωcm) and better optical transmittance (87 %) are obtained. ZnO films developed in this study with high transmittance and low resistivity and good electro-optical quality supports their use in transparent and conductive electrode applications. The plan presentation was visualized using Vesta, with the lattice parameter set as follows: a = b = 3.249 Å; c = 5.207 Å; α = β = 90°; γ = 120°. Based on the construction and optimization of primitive cells, the supercells were constructed and then optimized. Finally, (002) and (103) planes were cut and the planar supercell structure was constructed. In order to make a plane representation for the solid bulk with 10 Å of thickness
Analysis of Friction stir processed surface quality of AA2098 aluminum alloy for aeronautical applications
Get PDFFSP is a relatively new technique that changes the microstructure on the surface of the material to improve mechanical properties in the desired zone. This study aimed to investigate the surface quality of AA2098 sheets after being subjected to friction stir processing under different conditions of feed rate and rotational speed. A DoE analysis was developed with two factors, feed rate and rotational speed, and three different levels of 75, 100, 125 mm/min and 1000, 1250, 1500 rpm respectively, in order to assess the processed surface quality. The Sa parameter was used to represent the surface quality in different zones of the process, near entrance tool, middle and near exit tool, and ANOVA analysis was conducted. The results indicated that only the position and feed rate have a statistical influence on surface roughness. Additionally, the surface quality is strongly affected by the position relative to the entrance of the tool and the side (retreating or advancing sides). The roughness was found to be significantly lower on the advancing side rather than on the retreating side
Prediction of Impact Strength of TIG Welded Cr-Mo Steel Using Artificial Neural Networks
Get PDFWelding is a critical and energy-intensive process with significant importance in the manufacturing industry, enabling the creation of joints capable of withstanding diverse loads without failure. Accurate prediction of welding parameters' effects on the thermal cycle and strength of metals during and after welding is essential to ensure the reliability of welds. This study investigates the influence of welding parameters such as welding current, material thickness, number of weld passes, and electrode diameter on the impact strength of Cr-Mo steel bars. Pure tungsten with 2% thoriated Tungsten Inert Gas (TIG) electrodes was used to join the metal sheets autogenously. Artificial neural network (ANN) was used in creating the model that predicts the impact strength of the steel. Sample with welding parameters of 15 mm thickness, 90 A current, 3 weld passes, and Ø2.4 mm electrode size exhibited the highest impact strength. Furthermore, the analysis of variance (ANOVA) results show that the material thickness and number of weld passes contribute significantly to the impact strength of the steel. The ANN model trained by the Levenberg-Marquardt algorithm had an average training dataset root mean square error (RSME) of 4.12%. This study contributes to the reliability and performance of welded joints in various applications
Study the effect of adding vulcanized rubber powder on the mechanical properties and fire retardant of polyurethane Sealant.
Get PDFThe polyurethane Sealant (TRITOSIL H10 PU) mechanical and combustion characteristics were examined in this study as a function of the weight ratio of tire rubber powder (waste), with a particle volume of (150 μm). Elongation, tensile strength, Young's modulus, compressive strength, and rate of burning time were a few of the characteristics examined. The results showed that adding filler decreases the spaces between the chains of polymer, reflecting the polymer's high ability to withstand the stress imposed on it, that the degree of homogeneity between each of the fillers and polymers is high, and that increasing the percentage of fillers gives the prepared models a slight increase in hardness at a percentage increase (25%). Based on research into combustion resistance, The results of the experiments showed that increasing the amount of used filler has a positive impact on heat diffusion through the polymeric matrix and flame resistance. The use of filler as a filler has an impact on the properties of the polyurethane polymer, which has high mechanical properties. This increases tensile strength, which makes it appropriate to cover the flooring of indoor playgrounds, kids' playrooms, and other spaces.
 
Sorption of Pb2+, Zn2+, Cu2+ and Ni2+ Ions on Na-enriched Natural Zeolite for Wastewater Treatment Process: A Kinetic Approach
Get PDFLow-cost and easily available natural zeolite is a promising adsorbent for metal ions removal in wastewater treatment. The possibility of using zeolitic tuff from Serbia in the form of Na-enriched natural zeolite (Na-Z) for the adsorption of Pb2+, Zn2+, Cu2+, and Ni2+ ions from wastewater was investigated in the presented paper. The research included Na-Z characterization and determination of adsorption kinetics in individual ion adsorption tests using non-linear pseudo-first-order (PFO), pseudo-second-order (PSO) and mixed-order (MO) kinetic models. The results indicate that the adsorption processes of metal ions on Na-Z are complex processes dominated by multiple rate-limiting mechanisms and best defined by the MO model. The mechanisms of ion diffusion and adsorption to active sites are equally represented in the Pb2+ ions adsorption process. The mechanism of ion diffusion is more pronounced in the Zn2+ ions adsorption process, while in the case of the adsorption of Cu2+ and Ni2+ ions adsorption on the active sites is the main kinetic mechanism. Within the MO model, the PFO rate (external/internal diffusion) and the PSO rate (adsorption on the active sites) were calculated and results were applied to a multicomponent wastewater sample in order to determine and explain the adsorption efficiency in wastewater treatment. The results show that the rate of adsorption of individual metal ions and the efficiency of ion removal from a multicomponent wastewater sample are influenced by several factors including the radius of the hydrated ion and the free energy of hydration. The achieved removal of metal ions by Na-Z is Pb2+ (89%) > Cu2+ (72%) > Zn2+ (61%) > Ni2+ (58%) and defines Na-enriched natural zeolite as an effective adsorbent in wastewater treatment
A Review of Parameters and Mechanisms in Spray Cooling
Get PDFMiniaturisation in avionics, electronics, and medical appliances has led to demands for rapid heat dissipation techniques. The spray cooling technique has gained importance recently due to its advantage over other cooling methods. Parameters affecting heat transfer mechanisms during spray cooling are contemplated. This review presents different heat transfer parameters and their effect on spray cooling by analysis from past studies. Heat transfer surface modifications and different coolant variations to enhance heat transfer effectiveness are also reviewed. Apart from high heat flux having more applications, low heat flux studies have also grabbed the researchers to find solutions with a temperature range lower than 250˚C. Therefore, the upcoming spray cooling technology will have broad applications that will contribute to the maximum efficiency of the heat removal rate
In Situ Production of B4C and FeV Enriched Composite Surface on Low Carbon Steel by Cast Sintering Technique
Get PDFA simple and cost effective technique to obtain locally hardened composite layer on cast alloy was previously developed based on advantages of liquid-sintering theory. This methodology provides an opportunity to produce final product with hardened composite layer with good wear resistance during casting process. The current study investigated the effect of combined B4C and FeV substrates on the composite layer properties during in situ cast sintering technique for low carbon steel. Microstructure inspection, XRD phase analysis, chemical composition, thickness measurement and the hardness test on the produced composite layer were conducted. The technique produced up to 640 (±300) µm thick composite layer with maximum hardness of 481 (± 14.6) HV. The hardness of the reinforced surface layer is 3-4 times higher than the base alloy. The increased hardness of composite zone is directly attributed to the presence of the iron boron (FeB), boron vanadium (V2B3) and iron carbide (Fe3C). There were no significant effect of substrate composition on the produced thickness of the composite layer. However, an increase of FeV proportion in the powder mixture leads increased the hardness. The current study is a first attempt to produce locally hardened surface layer on the low carbon steel using simple and cost effective in situ technique with use of relatively inexpensive substrates. 
Study of Mechanical-Elastic Parameters of Reservoir Rocks with Respect to the Purpose of Permanent CO2 Storage
Get PDFCO2 emissions are considered to be partly responsible for climate change. One of the available methods to reduce CO2 emissions is its storage in favorable rock structures, such as mined hydrocarbon deposits. Natural hermeticity is guaranteed with this reservoir structure. An increase in pressure conditions in the deposit, induced by long-term CO2 storage, can lead to the splitting of exposed rocks. It is therefore necessary to carry out geomechanical tests on available drill core samples. The presented article presents the results of laboratory research aimed at determining the mechanical-elastic parameters of reservoir rocks of a hydrocarbon deposit using non-destructive testing. The advantage of this method is the possibility of testing the given samples before and after exposure to CO2. The laboratory research carried out revealed significant differences in the measured mechanical-elastic parameters of the tested samples. Taking into account that samples of the consistent reservoir structure of the same deposit were tested, the necessity of detailed testing of geomechanical parameters arises. It was interpreted that the differences in mechanical-elastic parameters found by the research may be caused by differences in the lithological composition (for these purposes, XRD powder diffraction was implemented), or by mechanical disturbance given, for example, by fracture predisposed by structural-tectonic processes. Different humidity can also have an effect, or degree of saturation of the tested samples