Al-Qadisiyah Journal for Engineering Sciences

Abstract ABSTRACT: - Surface roughness is an important criteria of the product quality in the machining operations. It is depends on cutting parameters. The objective of this research is to investigate experimentally the influence of cutting parameters on the surface roughness in turning operation, in order to determine the optimal settings of these parameters to improve surface roughness in the turning operations. In this work, surface roughness was measured for steel turned components, which was carried out on a conventional and on a computer numerically controlled (CNC) turning machine with carbide tool at different cutting parameters such as; cutting speed, depth of cut, feed, and the usage of cutting coolant. The experimental results were collected and analyzed. The relation between cutting parameter and surface roughness were determined. The experimental results show that the turned component surface roughness is significantly influenced by the cutting parameters, usage of cutting fluid, and the machine tools. The results obtained from this work show that the surface roughness of the turned components decreased by increasing spindle speed and it increased by increasing depth of cut and feed, while it decreased by using cutting fluid. Also the results show that the surface roughness for the turned components on the CNC machine was less than on the conventional machine using the same cutting parameters.

Abstract ABSTRACT One of environmental pollution and global warming sources is cement industrials. In line to diminish the effects of cement industrial activities on environment, wastes are used in cement mortar as a partial replacement of cement weight throughout the present study. These wastes comprise poultry egg shell which is wealthy in calcium and glass of bottles of juices and soft drink which has high content of silica. Both types of wastes were grinded carefully and passed sieve No. 200 ( 75μm opening size) to produce egg shell powder (ESP) and milled glass (MG). Cement was substituted by (5%, 7.5%, and 10% ESP), and (10% MG). These ratios of replacement was evaluated individually and in groups by compressive strength test at age of 28 days and drying shrinkage test at ages of 4, 11, 18, 25, and 60 days of drying. Results of tests indicated that compressive strength and drying shrinkage have the same trend when the replacement ratios of ESP used individually in mortar mixes. The higher results were recorded with ratios of 5% and 7.5%. While, compressive strength increased when 10% of MG was used as a partial replacement of cement, and drying shrinkage decreased at ages 11, 18, and 25 days of drying. The combination of MG and ESP in one mix, decrease compressive strength in all percent of addition. However the gathering of MG to 5% of ESP, and MG to 7.5% of ESP decrease drying shrinkage at all age of testing when compared it with the reference mix.

Abstract Abstract The increased demand for renewable energy calls for increased developments to the techniques of production for such energy. This paper presents a numerical study of conical collector solar chimney with specific dimensions. A glass spiral of square cross section was fitted to the collector to investigate its effects on the velocity distribution of air. Results show that the spiral enhances velocity distribution by (11.57% and 12.82%) corresponding to the inlet air velocity of (Re=99945 and 499729) respectively. This enhancement will reflect to the instantaneous electric power which can be produced by such instrument. The investigation was carried out using CFD program FlUENT14.5, K-ɛ model.

Abstract A thin film of titania (TiO2) was deposited onto AISI 316L steel using physical vapour deposition (PVD). Coating thickness was measured using Elecometer instrument and it was (150µm).Corrosion resistance to (H2SO4,HCl, H3PO4, and HF) acids with (2&4) pH, and to (NaOH, KOH,Ca(OH)2, and NH4OH) basis with (10,12) pH, of coated specimen was measured at temperatures ranges from (25-190) Co by weight loss method. It has been found that TiO2 coating largely enhance corrosion resistance of steel alloy especially at high temperatures.

Abstract Abstract Friction stir spot welding (FSSW) is a powerful and superior alternative to resistance spot welding and riveting for fabrication of aluminum sheet metal structures. The objective is to study the variation of transient temperature in a friction stir spot welded plate of AA6061 Aluminum Alloy. Numerical and experimental investigations were performed to study the temperature distribution during this process. Two thermocouples (type K) were placed at two specified locations from the pin hole to measure the transient temperature during FSSW welding process. Numerically, 3D finite element model was built using ANSYS workbench Ver.15 to simulate the thermal model during welding. The torque and axial load were measured experimentally to determine the coefficient of friction, which used with the other parameters, to find the applied heat flux for the welding process. The temperature distributions of the specimens welded by three tools with different pins; i.e. cylindrical, tapered and triangular, at constant other FSSW parameters, were investigated and compared with the experiment temperature measured using the thermocouples to validate the results. The results show that the temperature produced from the welded specimen with cylindrical pin shape has the highest temperature distributions due to high axial load and torque as compared with other tool pin profiles. Also the results show good agreement between numerical and experimental with a percentage error (-3.09 – 7.83) %.

Abstract Abstract The type of materials such as subgrade, subbase and base has a great effect on the quality and life of pavement. The nature of subgrade soil has the most important effect among other materials. There is a real concern in construction flexible pavements over a weak subgrade and the California bearing ratio (CBR) is very low for such soils. Therefore, the constructed pavements for such cases require more thickness. In fact, there is a need to look for economic methods in order to replace the lack of suitable construction materials for pavements such as subbase and base materials. This work studies the effect of geogrid reinforcement on CBR of subgrade soil and total pavement thickness. The soft sand soil from Al-Najaf city and one type of geogrid have been selected. It has been found that there is a significant improvement in CBR of subgrade resulting from geogrid reinforcement. The results indicated that the value of CBR was about 2.14% without using geogrid whereas this value was 12.84% in case of putting geogrid at 0.2H from the top of the specimen. Also, the reinforcement of subgrade with geogrid at 0.2 from the subgrade layer thickness will reduce the total pavement thickness by (30-40) %. Then, the same case study has been modeled using Plaxis (3D) software which is a finite element package. This package is equipped with specific features to deal with different complex cases and structures to simulate a realistic of case under study. The encouraging results have been obtained.

Abstract Abstract This paper presents an analytical calculation and experimental investigation to evaluate the American and British methods usually used for mix design of normal concrete. Six concrete mixes with different target of mean strength were design using crushed and uncrushed aggregates. A reliable approach has been suggested to calculate the mix proportions. In order to validate the former approach, an experimental programme was running to measure the workability aspect and compressive strength of three selected concrete mixes designed for strength levels of 21.5 MPa, 27.5 MPa and 36.5 MPa at different sample ages using 108 cubes. The results obtained showed notable differences between the approaches of American and British methods adopted to calculate the mix proportions. There was no indication have found in the American method to distinct between design the concrete mix containing crushed aggregate and that of uncrushed aggregate. The procedure followed in British method produced concrete mix with higher strength than that designed according to American method. The experimental results of compressive strength and workability showed close agreement with the suggested approach for calculation the mix proportions.