KUFA JOURNAL OF ENGINEERING

Copper (Cu) nanoparticles have attracted considerable attention because of their applications in many different fields. In this paper, Cu particles have been produced by means of a pulse laser ablation (PLA) process to ablate Cu metallic target submerged in two different mediums, water, and ethanol. The laser ablation process was occurred at energy by 900 and 700 mJ with wavelengths of 532 and 1064 nm. The UV visible spectrum was also characterized to investigate the optical properties. The atomic force microscope (AFM) and scanning electron microscope (SEM) were used to detect the nanoparticles of Cu. The results showed that the Cu nanoparticles could be prepared successfully in ethanol media at both laser energies 900 and 700 mJ for 532 and 1064 nm wavelength. Peak at 575 nm appeared in the U.V visible spectrum which indicates the formation of Cu nanoparticles. Furthermore, there is a slight chance for preparation of Cu nanoparticles in water media owing to the incidence of Cu oxides instead of Cu nanoparticles.

The pile foundation is usually designed to exceed the weak soil to the strong stratum. There is very close relation between the pile capacity and surrounding soil conditions. In cohesionless soil, the bored pile is effecting surround soil by loosening deposits through a combination of pile volume replacement and exist of pile case used for installation of bored pile. In this study, the improvement of the weak soil that surrounds the pile and observing the effect of improvement on pile increase the skin friction of the bored pile capacity for bored pile carried out. This study conducts research into the use of expansive additives in concrete bored piles. The aim of this project was to investigate how Na2Co3 as an additive in concrete can increase the shaft resistance of a bored pile. Several tests were conducted on concrete single piles with a variation of length to the diameter ratios and different percentages of soda ash additives. All tests were made in dry, sandy soil at loosening state. All tests showed that the shaft capacity could be increased using expansive additives due to increase the volume of the pile or enlargement of pile volume during concrete setting; it was also concluded that the shorter expansive piles could be able to achieve the same pile capacity as a longer conventional pile. This would lead to reductions on the volume of concrete poured, the amount of steel reinforcement used and the amount of soil excavated. Therefore, construction costs can be decreased and construction times can be shortened.

The goal of this study is to specify the optimal factors for the hardening process (tempering temperature, the percentage of nanoparticles, type of base media, nanoparticles type and tempering time) in order to maximize the hardness of medium carbon steel by using Taguchi technique. An (L18) orthogonal array was chosen for the design of the experiment. The optimum process parameters were determined by using signal-to-noise ratio(larger is better) criterion. The important levels of process parameters on hardness were obtained by using analysis of variance which applied with the help of (Minitab17) software to investigate the effect of parameters on the hardness. Percentage of volumetric fractions of nanoparticles with three different levels (0.01, 0.03 and 0.08%) was prepared by dispersing nanoparticles that are (α-Al2O3, TiO2 and Cuo) with base fluids (De-ionized water, salt solution, and engine oil). Medium carbon steel specimens were suffered to hardening and tempering heat treatment process. Tempering temperature was (400℃, 550℃) for (30,45and 60 minutes). Results ended up with a conclusion that tempering temperature (400℃) had the major influence on hardness behavior then type of nanoparticles (TiO2) followed by time tempering (30min) then base media (salt solution) and finally volume fraction of nanoparticles (0.03%).

Non-traditional machining process is more used to manufacture geometrically complicated and an accurate parts for electronics, aerospace and automotive industries. Chemical machining process is one of non-traditional machining methods, it is as well named as chemical etching. The current research is aimed to study the influence of the machining time, machining temperature, etching solution concentration on the material removal rate and surface roughness of aluminum alloy by using mix of acid FeCl3. There are three of machining temperatures (25, 30 and 35 ºC) with three machining times (4, 8, and 12min) and etching solution concentration (25%, 50%, and 75%) were used as machining conditions. These conditions are significant variables that have effect on finishing performance of chemically machined aluminum alloy. Machining time has the greatest effect among these variables. The time is the most important parameter for maximum Material Removal Rate (MRR), and the interaction between temperature and etchant concentration is the next important parameter for maximum MRR. The time is the greatest parameter for minimum Ra, the interaction between time and temperature is the next significant parameter for less Ra.

Nitric oxide generated from various sources like car combustion is one of the most surrounding pollutants, which can be transferred from one form to another in the presence of sunlight. Titanium dioxide considered one of the most environmentally friendly active photocatalytics that can be used with building materials safely and effectively to react with nitric oxides. To study the possibility for the reduction of air pollutants like nitric oxides, two types of substrates coatings were prepared. First, mixing nano particles of TiO2 with cement paste in two percents 3% and 6%. Second, mortar substrates coated with nano TiO2 aqueous solution. Two coating methods have been used dip and spray. A laboratory test procedure was adopted to assess the performance of the prepared photoactive specimens. The specimens were subjected to NO gas and there efficiency in gas removal was monitored with time. Results showed the effectivity of coating building materials with titanium dioxide, the removal of gaseous pollutants like nitric oxide reached to 98.85% when spary and dip methods are used. Mixing nano titanium with a percent of 3% was also efficient in the removal of nitric oxides, the removal reached to 97%. It was concluded that spray method was more practical to be used.

This paper presents the effect of heat treatment on ultimate bearing capacity and total settlement of soft clay. The soft clay that was used in this study was prepared by mixing Baghdad’s clay with sufficient water content which gives a shear strength of 7 kPa.Seven model tests were carried out on soft clay inside a cubic steel box of 750 mm side length after heat treatment, two of which were used as a reference without treatment for comparison. A special heating system was designed and manufactured for this purpose by using the gas as a source of heating through boreholes. Four square patterns casing boreholes having 3.5 cm in diameter and 30cm in length with spacing 3d, 4d, 5d, 6d and 7d (were d is the diameter of the borehole) and the time of heating was six hours for each model. A monotonic load was applied on an aluminum square model footing of 150 mm length and 20 mm thick placed on the center of surface area of the soft clay until the settlement exceeds 10% of the width footing. The results showed that the bearing capacity increases and the settlement decreases with spacing increasing until some limiting value (5d) then the bearing capacity decreases and the settlement increases. The 5d spacing is the best one where the bearing capacity increases nine times and the settlement decreases to one tenth compared with that without heating.

This paper deals with synthesizing of nanocomposites of unsaturated polyester (UP) filled with nano silica and investigation the effect of silica content on the tribological behavior of UP and nanocomposites . Silica nanoparticles were prepared by burning rice husk ash (RHA) as an agricultural waste material. Three different percentages as 2%, 6% and 10% of nano silica were added to the unsaturated polyester and dispersed by using ultrasonic waves method. As a result of agglomeration and sedimentation of nano RHA particles, dispersing by ultrasonic waves was very effective to terminate these challenges. X-Rays diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and scanning electron microscopy (SEM) technics were used for characterization of materials. RHA-UP nanocomposites were tested for their tribo-performance by pin-on-disc machine. XRD demonstrated that white rice husk ash consists of amorphous silica. SEM demonstrated that silica particles were distributed uniformly and well embedded within the polyester matrix. Results showed an improvement in wear resistance with relatively stable friction coefficient with the addition of 10% nano silica. Adding 2 wt% nano RHA negatively affected the wear resistance of RHA-UP nanocomposite .The best tribological performance of 10% RHA-UP nanocomposites achieved at load 10N. Incorporation of RHA with unsaturated polyester has advantages of reducing pollution, making the pollutant RHA as a valuable material to produce low cost and lightweight products with modified properties. Silica enriched RHA could prove to be cheaper anti-wear additives for producing high performance unsaturated polyester composites such as brake pads.

In this paper, two finite element models were performed. The fiber and matrix represented as two different materials in the first plate, while the second showed as a composite plate. The boundary conditions included clamped the plates on four ends and the dimensions of the composite plates were changed in this study. The finite element was performed and ANSYS 16.1 was employed in modeling. By comparing the results between the frequency ratio and mode numbers for different plate thickness, the results showed that natural frequencies calculated by these two model thickness of the (length/width) ratio will be more uniform and the error will be small. The numerical equations that performed from this study used to investigate the natural frequencies for longitudinal clamped composite plate.

This paper presents an experimental study of structural behavior of self compacting reinforced concrete beams strengthened in shear by vertical CFRP strips. The experimental work consists of casting and testing of eleven simply supported reinforced concrete beams. One of the tested beam was un-strengthened to be considered as beams, while the remaining beams were tested after being strengthened using vertical CFRP strips. In this study, three parameters were considered, the configuration of CFRP sheets wrapping system, i.e. two sides, U-shape and full wrapped, effect of horizontal strap of CFRP strips to enhance the vertical CFRP strips and CFRP amount. The results showed that the presence of horizontal strap of CFRP strips on the vertical strips increases the shear capacity of the beams ranged between (3-27)% for beams with the same properties, while the increase in the ultimate loads ranged between (20-26)% and (39.5-46)% by comparison of wrapping system (two side with U-shape) and (two side with full wrapped) of CFRP strips, respectively.

Fuel atomization in diesel compression ignition engines is significantly affected on the performance, evaporation, self-ignition, and emissions of the engine. Therefore, the quality of the spray atomization has to study at first. Algae-Derived renewable diesel fuel in a single hole nozzle atomizer has been chosen as an alternative fuel for diesel. The differences in physical properties of algae-derived renewable diesel, biodiesels (from palm and cooked oil) and pure diesel are effected on both spray characteristics and the internal nozzle flow. Numerical simulations are presented in this study using Eulerian-Eulerian technique to model the spray-gas interaction. The spray moments model has been used to characterize the spray parameters. First, the model is validated against the spray tip penetration of diesel spray characteristics obtained from the experimental data conducted in house-code using constant volume spray chamber and the results show a good agreement. Then, comparisons were made among the selected fuels. The numerical simulations show that the algae-derived renewable diesel is very similar to pure diesel and can be used as an alternative fuel.

Despite the potentials of dual reinforced particulate polymer composites to produce outstanding composite with enhanced wear properties, scholars have devoted insignificant attention to them. This paper introduces five diverse epoxy composites prepared in dual reinforcement blends. Using a mixed design L16 orthogonal array, Taguchi’s parametric optimization was conducted with some ratios between the wear parameters as a novel way of revealing the influence of their interrelatedness in the optimization process while the statistical modelling of the wear responses was pursued. Analysis of variance was also conducted as well as regression analysis. With experimental tests on the DIN abrasion tester, the (10OPP,15CSP)% composite obtained an optimal parametric setting of A1B2-3C3D1E4. The (10PKSP,15CSP), (10PSp,15ESP), (10OPP,15PSP) and (5PKSP,20ESP)% composites obtained optimal parameter settings of A3B2C3D3E2, A3B1-3,C3D1E4, A3B2C2D1E4 and A3B2C4D3E3, respectively. The correlation plots between the experimental and predicted values of the wear process and determination coefficient indicate a high level of accuracy of the models in predicting the wear behaviour of the composites.