Abstract: The purpose of this paper is to present the formulation of a new sector finite element based on the strain approach for the numerical analysis of circular thin plate bending. The element is named SBSPK and has four nodes and three degrees of freedom per node (3 d.o.f./node). From several numerical examples, it is shown that convergence can be achieved with the use of only a small number of finite elements. The results obtained are compared with analytical and available numerical solutions.
Abstract: A CAD/CAM system has become a dominant system in modern production techniques. In the attempts to facilitate the transfer of design data and geometry between the huge varieties of the International working CAD/CAM systems, the International Standard for the Exchange of Product coding system (STEP) is introduced (ISO Step AP-203). Extraction of the entities is the first step in the automated programming either for process planning, product classification or in programming for Numerical Control Machine Tools. This step is the aim of this paper in a line of several steps to build a complete CAD/CAM system for manufacturing of complicated products. A methodology is developed to extract each entity. Software has been built using Visual Studio C# - Version 2010. Interface is designed giving all the entities and showing the geometrical shape of the product. Different cases have been tested to verify the developed software and full successfulresults were obtained.
Abstract: Copper destined for electrical cabling require a compromise of mechanical properties and electrical resistivity. The drawing process accompanied by the formation of crystalline defects, such as gaps and dislocations, which leads to the increase in hardness, and therefore to the increase in resistivity, a very important characteristic for the conductivity and the efficiency of the cable. The scope of this work is to investigate the phenomenon of deformation texture evolution while copper wire drawn destined for electric cable-making and to understand its relationship with the electrical conductivity. In this study, we notice that the hardness and the resistivity increase with an increase of the deformation level. On the other hand, a slight decrease in the resistivity of the wires was observed after a holding time of 30 min at 260°C. The annealing of wires at 260°C for 9 min of holding time leads to a recrystallisation especially for high deformations and a gradual return of the mechanical properties and of the microstructure towards a state close to the state of the wire rod with the extension of time . The recrystallization texture is composed of the same components as the drawing texture, fibers <111>//ND (Normal Direction) and <001>//ND. The decrease in the intensity of the fiber after annealing is observed. On the other hand, the fiber <001> // ND remains stable.
Abstract: In this study, pure nickel oxide thin films were prepared by a sol-gel dip coating method with different withdrawal speeds, onto glass substrates and their structural, optical and morphological properties were investigated. The structural properties of NiO films were characterized by X-ray diffraction (XRD), Polycrystalline structures of the prepared films were detected. The optical properties of the films were studied by UV–visible spectrophotometer and the optical transmittance of the films within the visible and near infrared region was found to be more than 75% and decrease when the withdrawal speed increase. The surface morphology of the films was observed by atomic force microscopy and it was found that the root mean square (RMS) roughness increases from 3.78 to 15 nm when the withdrawal speed increased from 30 to70 mm/min. Thus, the withdrawal speed is a key factor to change the NiO thin films properties.
Abstract: One of the most common problems encountered in many industrial products and its applications is wear. The purpose of this experimental research article is to analyze the wear behaviour of Al-6063 based SiC composites using pin on disc testing machine. In this present investigation there are nine different samples of Al/SiC composites with 5%, 7% and 9% volume of SiC were prepared through stir casting process. The sliding distance of 500 meter and the load 10 N were applied for wear testing of these prepared samples. From the experimental results, it was observed that the sliding velocity is greatly affects the wear rate and on increasing the sliding velocity the wear loss increases. It was also found that the wear loss decreases by increasing the amount of reinforcement element. Scanning electron microscope was used to examine the wear surfaces and found that the micro and transverse cracks, mild and severe wear occurred in the composite worn surfaces and wear structure of the composites.
Abstract: Different grinding parameters of silicon nitride ceramic are researched at the process of internal grinding. The influences on the roughness of surface by the linear speed of grinding wheel (vs), radial feeding speed (f) and axial vibration speed (fa) are studied in the uniformity testing. The experimental equation of silicon nitride ceramic internal grinding is optimized. The machined surface morphologies of the ceramic specimen are measured by roughness instrument of Taylor-Hobson Surtroni-25 and scanning electron microscope of S-4800. The results show that with the increasing of the linear speed of grinding wheel the roughness of surface get reduced, and with the increasing of radial feeding speed the roughness of surface get raised. It is also inversely proportional to the axial vibration speed. The linear speed of grinding wheel has the biggest impact on the roughness of surface of the silicon nitride ceramic internal grinding among the three grinding parameters. With the increasing of linear speed of grinding wheel, the value of roughness of surface declines from 0.4095μm to 0.1726μm. The influences on the roughness of surface of the silicon nitride ceramic internal grinding by different factors are found out in the research, and its removal mechanisms are cleared up under different linear speeds of grinding wheel.
Abstract: In this study, AISI 430 ferritic stainless steel sheet with 0.6 mm thickness was joined by resistance spot welding using different electrode materials. The effects of electrode materials and welding parameters on the mechanical properties of welded samples are defined in terms of peak load. The hardness and tensile shear load bearing capacity of welded joint was determined and the microstructure of welded samples was also evaluated. The most suitable welding parameters for each electrode material were determined.
Abstract: Cement-based penetrating waterproof compounds compact the concrete structure due to penetration into the microcracks, pores and capillaries of slightly soluble crystalline hydrates. The coatings made from them do have some drawbacks such as low tensile strength and shrinkage, which may lead to cracks and reduce impermeability. Dispersed fiber reinforcement allows improving these parameters. The surface electric properties of glass fibers and polyester fiber were studied; their ability to be a substrate for the growth of crystalline hydrates was studied; X-ray phase and thermal analysis of cement hydration products with a complex chemical additive providing penetrating action were carried out; electron microscopic studies of the contact zone between fibers and crystalline hydrates were carried out; experimental studies of the dependence of the composition physical and mechanical and hydrophysical properties on the additive and fiber content were carried out. It was found that a dense liner of crystalline hydrates and hydrosilicate gel is formed around the glass fiber and polyester fiber with a silicone dressing size. Between the crystalline hydrates and the fiber surface, strong electro-heterogeneous contacts are formed, which provide the high physical and mechanical properties of the composite. The amount of the complex chemical additive and polyester fiber that provides the maximum strength and minimum water absorption of the composition is determined experimentally.
Abstract: This study deals mainly with the mix proportions using granite and unwashed gravel as coarse aggregate for self-compacting concrete (SCC) and its workability, by considering the water absorption of unwashed gravel aggregate. Mix proportions for SCC were designed with constant cement and fine aggregate while coarse aggregates content of granite-unwashed gravel combination were varied in the proportion 100%, 90%/10%, 80%/20%, 70%/30%, 60%/40%, 50% /50%, represented by SCC1, SCC2, SCC3, SCC4, SCC5 and SCC6. 100% granite (SCC1) serves as the control. The workability of the samples was quantitatively evaluated by slump flow, T500, L-box, V- funnel and sieve segregation tests. Based on the experimental results, a detailed analysis was conducted. It was found that granite and unwashed gravel with SCC1, SCC2 and SCC3 according to EFNARC (2002) standard have good deformability, fluidity and filling ability, which all passed consistency test. SCC1, SCC2 and SCC3 have good passing ability while all mixes were in the limit prescribed by EFNARC (2002). It can be concluded that the mix design for varying granite-unwashed gravel combination for SCC presented in this study satisfy various requirements for workability hence, this can be adopted for practical concrete structures.
Abstract: Use of waste materials in concrete is now a global trend for efficient waste management so as to achieve a sustainable green environment and with the added advantages of preserving the natural resources as well as producing a better performing concrete. This study examined the properties of concrete containing ground waste glass powder (GP) as partial replacement for cement. The waste glass was finely grounded into powder and the morphology imagery of the powder materials was carried out using scanning electron microscopy (SEM). Moreover, the chemical composition of the glass powdered material was determined using X-ray fluorescence (XRF). Laboratory tests were carried out to determine the strength activity index, workability, split tensile and compressive strength properties of the concrete with 0%, 15%, 18%, 21%, 24%, 27% and 30% partial replacement of cement with the ground waste glass powder. The results showed that the oxides composition of the glass powder meets the requirements for pozzolanic material, while the SEM morphology shows materials of amorphous flaky solid masses, and based on the 28-day strength activity index, concrete containing 21% cement replacement shows a higher strength index above therecommended 75%. It was also observed that workability of the concrete reduced with increase in percentage glass content while significant improvement of the compressive strength of the concrete was achieved at 21% cement replacement, after which a decrease in strength with increasing percentage glass content was observed. The revealed results were confirmed by the microstructural examination using SEM showing a denser concrete at 21% cement replacement but increase porosityas the glass content increases. However, a decrease in split tensile strength was observed with increasing glass content. The results clearly showed that it is possible to produce moderate strength sustainable concrete for structural application using 20% glass powder as cement replacement.