Iraqi journal of mechanical and material engineering

The present research is concerned with the strengthening of reinforced concrete slabs with epoxy – bonded steel plates. The strengthening is intended to enhance the inherent resistance of existing slabs. The strengthened slabs have been analyzed through the experimental program done. The parameters studied in the present study are the thickness, dimensions, and location of steel plates. The more effective parameter which enhances the overall behavior of R.C. slabs is the effect of steel plate dimensions more than the thickness effect The max increases in ultimate strength are found in slabs S3 and S5 as (135%) and (79.6%), respectively. From the analysis results, using steel plates for strengthening of R.C. slabs can enhance the overall resistance of these members significantly.

The zeotropic blends comprise of R-407C and R-404A refrigerants and the pure R-134a were selected as a drop-in substitutes for R-22 in a water chiller under a quasi-steady state operation. When comparing the performance of the refrigerants with those of R-22, the results showed that R-407C, R-404A and R-134a reduced the cooling capacity up to (6) %, (6-12) % and (18) % respectively. R-134a and R-407C exhibited higher power consumption per ton of refrigeration than that experienced with the R-22 tests by (8-28) % and (7) % respectively. Whereas, R-404A showed a lower corresponding value than that of the R-22 by (9) %. The R-407C and R-404A showed a significant reduction in the actual (COP) by (19-23) % and (22-55) % respectively. The (COP) of the R-134a showed oscillation when compared with R-22 ranging from (22) % lower at high water inlet temperature to (29) % higher at low water inlet temperature.

Aim of this Reasch to Study Some Physical and Mechanical Properties of rubber such as( the Electrical conductivity ,hardness,tensile strength at break,Modulus of elasticity at elon.300%,Elon.at break,Torque,Scorch time(Ts2)) for taypes of rubber for example natural rubber (NR) and industrial rubber (butadiene-BR) by using conductive carbon black with addition Loading level (10,20,30,40,50 pphr) from conductive carbon type( N375) . also using fixed quantities from (CaCO3) and metals oxides e.g ( Fe2O3) and ( ZnO) are not effecting on mechanical properties for final product where giving the experimental results that improvement of electrical conductivity and mechanical properties for Natural rubber(NR) more than of thes properties in industrial rubber(butadiene- BR) as same as for loading level of conductive carbon

This study has been carried out to determine the feasibility of COD adsorption on iron coagulant by EC process, and to find a mathematical model using kinetic isotherms. Experiments were carried out to treat a high strength wastewater of textile industry located in Al-Hilla-Iraq using a batchwise mode. A well-rounded range of current density was tested and the COD removal percent has reached a maximum value of 85.2 under c.d. of 20mA/cm2. It was attempted to fit the experimental data with the popular adsorption isotherms Langmuir, Freundlich and Temkin, hense the mechanism of adsorption with the effect of individual parameters on the efficiency of electrocoagulation have been critically examined. Two well-known coagulant mechanisms were modeled with the kinetic equations utilizing the result from experiments relative to EC of COD removal for five set of experiments. It has been found from the present analysis that the adsorption isotherm with iron (II) and iron (III) hydroxides combined to generate hydroxo cationic-anionic complex of green rust mechanism, can be described by Langmuir isotherm equation which gives a preferable fit of experimental data than the Freundlich and Temkin isotherm model equations.

This research presents an investigation on the technical feasibility of design and manufacturing the ceramic water candle filters made from Iraqi raw materials to improve the domestic water quality to standards suitable for human consumption in villages and country side, the performance assessment is based on its porosity, turbidity reduction, bacteria removal, ease of flow, hardness and undesired ions reduction, so number of experiments were done by mixing different percent of the raw materials of which activated kaolin clay 15 to 45 wt%,coal 15 to 40 wt%, and porcelanite 15 to 40 wt%, with same grain sizes less than 75 microns. All of these mixtures were molded under constant firing temperature and hydraulic compression pressure (1200 0C, and 1325 kg/cm2). The effect of different feed percent for each material gave the optimum percent of 25%wt activated kaolin clay, 35%wt coal, 40%wt porcelanite reaching to the better tests results, number of tests also is made over the experiments range such as apparent density, porosity, wettability, turbidity, TDS, E Coli, water ions examination tests, the produced filter porosity was 62.3%, water turbidity reduced from 167 NTU to less than 5 NTU.

In this work the thermal behavior of malignant and healthy human tissue while exposing to ultrasonic waves was studied. Some stand-alone heat therapy is described numerically using Pennes equation which was solved using three level time step procedure to avoid iteration. The efficient procedure of solving the equations by avoiding time consuming procedure of iteration was combined with band solver matrix solution enhanced the program efficiency (i.e. reduce the time of calculation and the size of the program( . The temperature distribution was obtained first from which the thermal dose required to shrink a tumor was calculated using well-known thermal dose equations and then the zone that had been necroses was obtained where an effective procedure is proposed to shrink the cancer cells that may exist in certain human tissues. The controlling of the heat dose is the main factor in determining the affected zone by chooses a suitable acoustic window, power and time. The suitable heat can be generated with a human body so as to kill the cancer cells where they may exist. Cancelling the heat source, the temperature of the skin was obtained numerically which was found with good agreement with real skin temperature.

Electro chemical machining (ECM) is a non traditional process that can machine difficult to cut material. This paper was focused on methods which are used to enhance metal removal rate (MRR) and surface finish during experimental investigations, were the work materials are two aluminum alloy ( AL Zn Mg Cu 1.5-DIN 1725-1) and aluminum 1100 with using brass and steel ck35 tools, also NaCl solution as electrolyte was used. Experiments prove that increasing electrolyte flow rate from 6-14 l/min at electrolyte concentration 200g/l lead to increase metal removal rate reach to (63.07%) and enhancement of surface finish by reducing roughness from (5.07 to 3.25 µm ) minimum and from (6.63 to 1.2 µm) maximum using work material from aluminum alloys to perform that . Also there are another factors influencing in metal removal rate and surface finish such as voltage and frequency when increasing them from (10-30)V lead to increase MRR about (29.45%) and frequency from (100-500)HZ improved MRR by (34.17%)

The purpose of this study is to examine the change in the wall thickness of drawn cup by using fixed blank holder gap (BHG) and variable blank holder force (BHF) to hold the sheets metal during drawing operations. The effect of BHG and BHF on drawn cups was studied by the experimental and theoretical approach. Two blank holder gap, BHG = 0.5, and 1 mm and variable blank holder force were used in the experiments. The study shows that a type of blank holder has a great effect on the quality change of the wall thickness of the final product, and BHG and BHF are considered important parameter to control material flow. Punch and die with diameters 43mm, 44 mm respectively are used to draw low carbon steel sheet (1008-AISI) with a thickness of 0.5 mm to draw a (cylindrical cups) from blanks with different reductions 0.5,0.55, 0.6, 0.65, and 0.7. The punch and die have the profile radius 4mm. Press with a maximum load capacity of 200 KN with speed 10 mm/mint was used to perform this research. The results show that no change occurs in the thickness of cups at ρ = 0.6 R, radius of blank, whereas the maximum change (thickening) of the wall thickness occurs when ρ = R, and the minimum value (thinning) of wall thickness in the corner of the cup. All values which estimated theoretically are slightly different for measured experimentally. The best results were obtained from the BHG = 0.5 mm compare to BHG = 1mm and BHF.

In the present work, effect of laser energy on optical and morphological properties of In2O3 trioxide thin film has been carried out using Reactive Pulsed Laser as a Deposition technique (RPLD). Q-switch Nd-YAG laser with (λ=1.06nm,tb=7nsec) and different energy's has been use to ablated pure indium target and deposited on glass substrates and constant substrate temperature of (333K). The results films show that high transparency reached to about (80-95) % can be achieved with In2O3 film which itself decreases sharply with the decreasing of laser energy while the optical band gap is( 3.6-3.8) eV at optimum laser energy (400mj ). The optical properties of the prepared include optical microscopic measurement, optical transition measurement, surface uniformity measurement and FTIR.

In this research, the effect of shear modular G23 variation is investigated on the twisting strength of a unidirectional fiber reinforced composite rod subjected to various uniform static twisting moments. An optimization of the best modular ratio is also made to determine the maximum allowable twisting strength. The problem is simulated by the software of ANSYS v12 to determine the stress fields distribution throughout rod domain and the section of highest shear stresses in different planes (critical sections), a graphical representation has been made to the results obtained from a finite element analysis to rod of interest. The elastic properties of the composites investigated are found using the rules of mixtures and Halpin-Tsi equation along with the sftware of Matlab v6.5. Various types of fibers and matrices are used to change the shear modulus of G23 . It is found that most dominant effect is that of matrices whose the increase of its shear modulus (Gm ) is getting inversely proportional to angle of twist (θ) according to a certain polynomial function of a second degree and there is a minor effect of fibers on it. The results of the analysis made by the package of ANSYS v12 were compared with the analytical solution showing the same behavior and reasonably convergent values.

This research is concerned the use of Epoxy resin( Cy223 ,Hy956 )which supplied from (Giba –Giegy) German company .It is a viscause liquid have a certain properties like high adhesives and low shrinkage at dry condition with addition of the hardener at ratio (1:3 ) of the resin with density about (1150 kg/m3 ) , the matrix resin forced with two type of fibers : glass fiber( E-glass) and carbon fiber (HS )(High Strength) ,the ratio of carbon fiber layers to glass fiber layers is (1:5) with volume fraction (30%) at room temperature to study tensile and fatigue tests. It is noted that the composite materials appears better resistance to the tensile test than the resin due to the resistance of fiber(especially carbon fiber which have a good mechanical properties ) .In the fatigue test , the composite material show good strength to break because of the resistance of carbon fiber at low cycle . The resistance to break remains constant or changed slowly with increasing cycle of fatigue strength depending on supporting ratio.

This study introduced a material combined between these characteristics , this material is antimony trioxide. In the present study , the preparation method of antimony trioxide and manufacturing method to form insulation layer from this oxide as a thickness of coating layer (3mm) were expressed , which paste on the composite material consist from unsaturated polyester resin and glass fibers type-R , which acts as a paste and hold material to the insulation and flame retardant oxide. Thermal erosion test was done with gas torch to evaluate the performance of the antimony trioxide efficiency to thermal insulation and flame retardancy. The result obtained from thermal erosion test done at (2000°C) were showed that the antimony trioxide efficiency of as a flame retardant material .

In this research , effect of addition silicon oxide (SiO2) on electrical and thermal conductivity of unsaturated polyester resin has been studied , where this oxide was added to resin with different weight amount (5%,15%,25%) . The results show increased electrical and thermal insulation of the resin after addition this oxide , where the electrical conducting was decreased from (1 E-14) before adding oxide to (1 E-16) after addition (25%) from silicon oxide at (40 °C) ,also thermal conductivity was decreased from(0.72 W/m. ºC) before adding oxide to (0.57 W/m. ºC) after addition (25%) from oxide at (60 °C) .

This research is devoted to study the effect of some additives such as glycerol, oat flour, rye flour, glue, PVC and Na2CO3 on properties of sand moulds then their effects on cast iron castings resulted from casting in these moulds. To prepare sand mixture with suitable properties for casting the required metal, various percentages of additives were added (after selecting the optimum percentage of bentonite and water) to the mixture to show their effects on the properties of the sand mould. Several tests were performed on the castings showed that those obtained from pouring in a mould composed of a mixture containing 0.5% glue, have better surface and mechanical properties, where the mould hardness was (75 Brinell scale) and its green strength was (0.046 MPa) in comparison to other additives, which gave less surface and mechanical properti

The aim of this research is to study the effect of plastic deformation of aluminum alloy (7020-T6) sheets metal with (10 mm) thickness by cold rolling process. The deformation ratios are (5 ,%10,%15 ,%20(%respectively from the original thickness. The sheets are prepared with dimensions (10 × 50×100 mm) and then passed through a pair of rolls with diameter of (50mm). The tension test is carried on specimens which manufacture according to (ASTM E8) standard for each forming ratio. The hardness and grain size of the specimens were measured and the microstructure was inspected in order to know the effect of plastic deformation ratio on them. Rolling process was contributed in improvement for the mechanical properties of the alloy are increasing for the all forming degree and the best ratio was (15%). The ratio (20%) lead to small cracks in the specimens, as it appears in microstructure pictures. The ratios (5% &10%) produce inhomogeneous deformation , is not usually a desirable situation, which is lead to high increasing in the values of pressure and force of roll. This often corresponding to sticking friction conditions. On the other hand, the ratios (15% & 20%)produce homogenous deformation.