Iraqi journal of mechanical and material engineering

This paper studies the performance of a single cylinder compression ignition engine Ricardo E6, fueled with different blends of ethanol added to diesel.The brake specific fuel consumption for dual fuel, in general, is higher than that for the diesel engine for low and medium loads; however, it becomes less than the diesel engine for high loads. The increase in the proportion of the ethanol in the mixture improves the specific fuel consumption at any specific load. The brake thermal efficiency for diesel engine is higher than that for dual fuel engine for low and medium loads, while it becomes lower for high loads. In general, the addition of ethanol in the mixture improves the efficiency. Retarding the injection timing of diesel fuel caused the specific fuel consumption to increase steadily to about 40% when the timing is too late. The thermal efficiency of dual fuel is lower, in general, than that of the diesel engine when retarding the injection timing.

In this research, the optimum design of a manned aircraft wing structure at speed (M=0.4) is estimated for both isotropic and orthotropic material. Firstly the stress analysis for wing structure due to aerodynamic loads is computed. The wing is considered as a cantilever through the contact points with the aircraft fuselage. The stress distribution and deflection for each point of the wing structure is found for both isotropic and orthotropic material. Secondly, the optimum design (minimum weight) for both isotropic and orthotropic material is estimated. Two methods were used to find the optimum design of the wing structure. In the first method the MORPHING criteria was programmed and used as optimizer program in conjunction with ANSYS11 program as solver program, Ansys Parametric Design Language (APDL) is used to write the MORPHING method. In the second method, the ANSYS11 program is used for both analysis and optimization. The results found by using the first method show (22.7%) weight reduction for isotropic material and (23.2%) for orthotropic material. The result found from second method show (24.4%) weight reduction for isotropic material and (24.1%) weight reduction when using orthotropic material

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Nickel-Aluminum Bronze (NAB) alloys have properties meet many requirements in engineering applications. But many, especially the alloy C63200 suffer weakness in machining properties, so the current study aims at improvement the machineability of this alloy without loss their mechanical properties. A base alloy of (Cu-9%Al-5%Ni-4%Fe) composition was prepared by compacting mixed powders of the constituents under a pressure of 656MPa and sintering at 950℃ for 50min in special atmosphere, then heated to 900℃ for 45min and quenched in water and then aged at 500℃ for 25min. Under the same conditions other samples of the alloy with various percentage of graphite or/and SiC additions were prepared. The effects of these additives had been studied. Machineability was represented by a tool life of a 3mm-diameter high speed steel twist drill. A maximum width of flank wear of 450μm was considered as a criterion of tool life. Three cutting speed (0.95, 1.7, 3m/min) each with three feed rate (0.1, 0.25, and 0.4mm/rev) were considered as cutting conditions. The study showed that (0.6%graphite) reduces the hardness by (11%) and the porosity by (30%), while (2%SiC) increases the hardness by (14.7%) and the porosity by (13%). Adding 0.6%graphite and 2%SiC together causes a decrease of (9.7%) in porosity and an increase of only (1.2%) in hardness. A maximum increase in tool life of (27%) was achieved with an addition of (0.6%graphite) while a maximum reduction of (29%) was recorded due to (2%SiC), but (0.6% graphite) with (2%SiC) caused an increase of tool life by (7%).

Hypereutectic aluminum–silicon (>13%Si) alloys have been used for many engineering applications due to their properties. A continuing problem with these alloys is that they are difficult to machine, tool wears rapidly due to the hardness and abrasive nature of the Si particles, so repairing this problem is very important. In this work, the hypereutectic Al-Si alloy samples were prepared by stir casting. Effect of solidification under mechanical vibration with three frequencies (32.5, 100, 124.5Hz) and constant amplitude (0.5 mm) as well as an addition of 0.3% graphite was studied. Several mechanical, physical, and machineability tests were carried out. Machineability tests were related to the surface roughness and tool life. A maximum width of flank wear of 300μm was considered as a criterion of tool life. Carbide tips type P10 with dry turning operations were used at a constant depth of cut of 0.5 mm. Four cutting speeds (15, 21, 31, 45m/min) for each of which four feed rates ( 0.005, 0.008, 0.01, 0.016 mm / rev) were used as the machining conditions. Results showed that adding ( 0.3% Graphite ) to hypereutectic (Al–Si ) alloy accompanied with solidification under vibration improves its microhardness by (26%) and tensile strength by (102% ) and modulus of elasticity by (20%). The results of machining experiments showed depressing in tool flank wear and improving surface finish. This was true for all regarded machining conditions. The surface roughness was reduced by (20-38%) with the used machining conditions, while an increase of ( 76 -94% ) in tool life was achieved.

Rayleigh and Rayleigh-Ritz represent the two approximate analytical methods which can be used in this paper in order to study the characteristics of free transverse vibrations of cantilever beam in the two cases. The first one is at tapered thickness and constant width while the second case is at tapered width and. The free end of the cantilever is sharp in both cases and is of different values of length. The study selects the value of thickness at clamped end (hc) and change the values of width at this end (wc) with thickness ratio which equals to ( 0.1 – 5 ). The second case on the other hand, can select the value of width (wc) at clamped end then change the thickness (hc) at ratio ( 0.1 – 5 ). Through out the results, it is shown that the cantilever beam at tapered thickness has natural frequency lesser than that of tapered width of the same length and at the same dimensions of clamped end, the natural frequency decrease with increasing the length of cantilever beam also with decreased the value of tapered thickness or tapered width according to this study. In case of different values of tapered width for the same length of beam and the same value of thickness at clamped end the cantilevers have the same value of frequency, also the cantilevers have constant frequency at tapered thickness for different values of ( ), while in the case of tapered width the frequency increases with increasing the value ( ) for the same (wc) and at the same length of cantilever beam.

In this paper the effect of filler content on D.C and A.C electrical properties of polystyrene filled with copper powders has been investigated. The D.C conductivity of such composites increases suddenly by several order of magnitude at a critical weight concentration. The D.C electrical conductivity changed with increasing of temperature. Also the activation energy change with increasing filler concentration. The dielectric constant, dielectric loss, A.C electrical conductivity are increasing with increasing the concentration of the filler and frequency of applied electrical field.

This research tries to study the using of rice husk (RH) as a filler with rubber compound based on Natural rubber (NR) that was prepared using an mixing mill about 80 ̊C and 50 rpm with different weight fraction (part per hundred Rubber) as (0-5-15-25pphr)with particle size between (250-500) µm , the results show the tensile strength and viscosity decreased with RH loadings in the matrix, while the tensile modulus and hardness showed an opposite trend. The weak filler -matrix interaction, resulting in poor filler dispersion and large agglomerated particles size, caused those properties to decrease. However, some mechanical properties of the rubber compound can be slightly improved with the addition of (RH) into the matrix while other properties decrease weather the overall rheology properties for all samples almost being little change.

Laminar burning velocities and Markstien length for blends of Iraqi diesel-oxygenates (methanol, ethanol, subflowers biodiesel and yellow grease biodiesel)-air premixed flames are investigated using the spherically expanding flame with central ignition, using constant volume and thermocouples connected to data acquisition system. Unstretched laminar burning velocity, Markstein lengths, Lewis number, Zeldovichnumber and Karlovitz number were obtained at wide range of equivalence ratios (Ø from 0.2 to 1.7).The Study indicates that although the tested blends are diesel-oxygenates, laminar burning velocities give an obvious difference which demonstrates that thr molecular composition has a great effect on laminar burning velociries of fuels. Maximun laminar burning velocity values occurs around equivalence ratios Ø=1.1. Increasing equivalence ratio influnced Markstein lengths to be decrease for the tested blends-air mixtures. The Zeldovich number maximum values obtained at stoichiometric equivalence ratio (Ø =1.0). The results show that the Markstein lengths were relatively independent of Karlovitz numbers.

A novel analysis of three stories - building, using finite element method via ANSYS software with nonlinear spring is presented. The investigation is carried out to show the natural frequencies and the response of the building under nonlinear effect of spring. The free and force vibration of a building with a non-linear spring–mass system has been investigated. The non-linear spring appears in the form of quadratic, exponential and logarithmic equation. The transient and modal solutions are done by using ANSYS to the non-linear system. The results of the linear frequencies and the response matched well with those obtained in the mathematical model. Subsequent non-linear study indicates that there is a pronounced effect of the non-linear spring and its mass. The exponential equation of nonlinear stiffness gives the highest magnitude of three modes of the natural frequencies with 0.0371% ,0.014% and 0.07% respectively of other cases of form equation (quadratic and logarithmic).

Surface Roughness (SR) is considered one of the most important indications to specify the quality of machined parts. There are many machining parameters having a large effect on it. The objective of the present study is to find the optimum conditions in turning of Al-12%Si alloy to get lowest surface roughness by applying the Taguchi method. The basic parameters which were taken into consideration in this work are: cutting speed, feed rate, and depth of cut in order. Experiments have been conducted by using L9 orthogonal array with three levels for each parameter. The nine test specimens were machined in terms of their levels, and average of SR (Ra) values were measured by means of surface roughness tester SRT 6210 device. The optimum combination of process parameters has been found through analysis of main effects for Ra and Signal-to-Noise S/N ratio, and the significant parameter was identified depending on ANOVA analyses. In the present work, the results show that the significant factor is depth of cut followed by feed rate and cutting speed, and the obtained results from the experiments are acceptable for the ranges of cutting conditions that have been selected in this case study. The predicted values and measured values are fairly close, which indicates that the Taguchi method can be effectively used to predict the surface roughness

The cost due to corrosion Damage have estimated to be 3-4% of their gross national product which significantly Countries problem around the world. In this study, a novel carbon steel pipe protection based on radial basis function neural network RBFNN was proposed. The RBFNN used to predict the minimum current density required in impressed current cathodic protection to protect low carbon steel pipe. Learning data was performed by using a 25 samples test with different concentration C%, temperature T, distance D and pH. The RBFNN model has four input nodes representing the (concentration C%, temperature T, distance D and pH), eight nodes at hidden layer and one output node representing the min. current density. Generalization test used 5 data samples taken from the experimental results other than those data samples used in the learning process to check the performance of the neural network on these data. In addition, the experimental results indicate that proposed system can be used successfully to obtain minimum cathodic protection current density to protect low carbon steel pipes.

A new type of porous brick is proposed .Feathers Livestock is well mixed initially with wet clay so that when the clay and feathers livestock mixture put in a mold of brick and entered the oven in firing process , voids are created inside it .The created voids will enhance the total performance of the brick since its reduced density32% ,thermal conductivity41% ,and increased compressive stress 18% , all these properties are measured experimentally and good performance has been obtained .From this work , it has been obtained that ,as porosity increased ,the thermal conductivity and density are reduced and a margin reduction in compressive stress is observed but the compressive stress is still larger than that of the common used hollow brick . These measured data lead to obtain new type of effective brick having good performance with no possibility of mortar to enter inside the holes of the common used hollow brick .The mortar has a determent effect on thermal properties of the wall.

In the near future, hydrogen will be required to supplement and eventually replace rapidly diminishing hydrocarbon fuels resources for internal combustion engines. Engine variables effects like compression ratio, equivalence ratio, spark timing and speed on combustion properties, engine performance were studied in this paper, when hydrogen supplemented natural gas is used in variable compression ratio, single cylinder Ricardo E6 engine.The results show that adding hydrogen to natural gas increase compression ratio, brake power and indicated thermal efficiency. Also this addition reduces brake specific fuel consumption, volumetric efficiency and exhaust gas temperatures. Optimum spark timing is retarded with adding hydrogen to NG.

In this study an experimental work has been conducted to show the effect of Ge and Si additions on the micro structure and thermal properties of pure Al, as the specific heat at constant volume (Cv), thermal conductivity (k), and thermal diffusivity .Six samples have been casted with different addition percentages of Ge and Si (10,20,30%).The results shows as the Ge addition percentage is increased, the alloy density is increased by (29.34%), the thermal conductivity is decreased by (20.85%),the specific heat is decreased by (19.4%) and thermal diffusivity is decreased by (24.1%). But as the Si addition percentage is increased cause decreasing the alloy density by (4.21%), the thermal conductivity by (7.3%),the specific heat by (6.7%) and increasing the thermal diffusivity by (3.7%).Through this study it was found that the best addition is 30% (Si) addition percentage for pure Al gives highest thermal properties (Cv,k, ) compared with the same addition percentage of (Ge) .and from micro structure , it was found the distribution of (Si) particle through (Al) . phase , for the (Ge) particle it was found the a glomeration of (Ge) particle is because the weak of the wetting property of (Ge) comparing with the (Si) particles

The Present research included study the effect of calcium carbonate extracted from oyster shells on rheological properties of natural rubber which added in different amount (20,30pphr).The calculating properties was :scorch time ,cure time ,viscosity and max torque . Oscillating Disk Rheometer was used to measuring the above properties by specified the behavior of master batch through scorch time. The obtained results shown that decreased scorch and cure time when added shells powder with increasing scorch time at (30pphr) ,also increased rubber viscosity after shells powder , and decreased rubber max torque at (30pphr) from shells powder due to decreasing scorch time

The research aims to use shells powder as a filler adding to natural rubber with different amount (20,30,50,100,120,150 pphr) and observe its effect on mechanical properties of rubber which includes hardness and tensile strength . The obtained results from mechanical tests shown improved in rubber hardness after adding shells powder and increasing this property with increased percentage of powder ,but tensile strength increased to (20 pphr) and then strongly decreased after this percentage

The aim of present work is to study the effect of the change of reinforcement percentage by fibers on the thermal conductivity ofr polymeric composite material consist of araldite resin reinforced by different percentage (20%,40%,60%) of chopped glass fibers .Fourier law for thermal conducting was used to calculate the thermal conductivity coefficient (k). Also reinforcement percentages (20%,40%,60%) was used to manufactured the mechanical tests specimens included impact strength, tensile strength, compressive strength as illustrated in diagrams which represent the relation between thermal conductivity coefficient (k) with temperature and between mechanical properties and reinforcement percentages

Silica material was added as a filler to unsaturated polyester resin with different weight percentage (1%,2%,3%) and study the effect of these additions on thermal conductivity coefficient of the resin. Fourier equation was used to calculate the changing in thermal conductivity coefficient (k) for unsaturated polyester resin before and after addition silica particles . The results show increased thermal insulation of the resin by reduced thermal conductivity coefficient value after addition this material . Also the value of thermal insulation increased with increasing of additive percentage of silica as illustrated in diagrams which represent the relation between thermal conductivity coefficient with temperature.