DIYALA JOURNAL OF ENGINEERING SCIENCES

One of the important aspects of mechanical design is improving fatigue life.;In this work, the effect of Ultrasonic impact treatment (UIP) and shot peening (SP)on constant cumulative fatigue life and fatigue strength of AA7075-T6 were studied; The sample group was machined and primed, and some specimens were treated using ultrasonic impact therapy (UIT) with one line of peening. Fatigue experiments were conducted under constant and variable amplitude (R=-1) at ambient temperature to determine the fatigue life of the S-N curve and fatigue strength during treatment 3.46% and 8.57% at 107 cycles for (UIT) and (SP). Cumulative fatigue damage testing was carried out for two steps loading it is observed that the fatigue life for SP and UIP treated specimens was improved compared to the unpeeled results. The fatigue endurance limit was enhanced by 35% for UIT and 54% for SP. The fatigue life for both treatments was much improved compared to as-received metal. These results also show a strong tendency of increasing fatigue strength after application of (UIT) and (SP) with an increase in mechanical properties of the material used.

Digital image processing (DIP), is the use of a digital computer to process digital images through an algorithm. In this work DIP used to perform crack/defect Detection and geometry measurements in terms of angle, length, and width by building a MATLAB code. In this research, the test of tensile were applied on two flat samples, the two flat samples are painted in a speckle pattern on the tested surface to use DIP features. The DIP gives a low-cost optical, and an appropriate technique to detect crack/defect as well as geometry measurements with the loadincrement in terms of angle, length and width without any contact with the tested surfaces. The tests directed for both of flat Aluminum alloy and Copper alloy specimens. In order to guarantee the efficiency of the planned DIP systems, the comparison is considered between the test results of this technique with the measurements gained by actual physical by using calibrated digital vernier calliper (IP 54) to measure the length of the crack with 0-300 mm range and 0.01 mm resolution. The DIP obtained percentage of accuracy varies from (97) % to (99) % by comparison with the measurements gained by actual physical way.

The corrugation configuration played an important role in heat transfer enhancement in many engineering applications such as heat exchangers, microchannel heat sink, solar collectors, etc. The significance of the corrugation configuration was manifested in its ability to offer a larger heat transfer area more than a straight channel. Besides, the periodic interruption and redeveloping of the thermal boundary layer which was an important feature offered by corrugation was remarkably enhanced the heat transfer. The researchers were keen to take advantage of these features and develop them by manipulating geometrical parameters to obtain the optimalresults. The current work aims to collect available research data, which focused on improving heat transfer in corrugated channels and identifying the most important factors affecting the performance of corrugated channels. Several corrugated channel shapes were demonstrated including sinusoidal, trapezoidal, house-type, and V-type. Among the studied shapes of the various operating conditions of the corrugated channels, the researchers unanimously agreed that the trapezoidal shape of the corrugations gives the best thermal improvement with a reasonable pressure drop inside the channels.

Hybrid energy systems is an energy system which employs the combination of various renewable energy sources (solar, wind, biomass, hydro, and hydrogen fuel) with conventional energy sources to supply electricity. These systems have become reliable and most cost-effective as compare to single-source energy system for rural electrification. The objective of the present study is to address the demand for electrification of remote rural village in eastern Iraq. The methodology is carried out for optimization of hybrid energy system comprising (Photovoltaic, battery, diesel generator) by using HOMER to minimize the cost of energy and the greenhouse gas emissions. For different configuration of energy sources, the capital cost, net present cost and cost of energy is determined for the optimized hybrid energy system on the basis of the electric consumption demand for the selected site. The simulation results show that the most techno-economic analysis for hybrid energy system can feed the rural village in eastern Iraq to meet a daily load of 30 kW has consisted of 6 kW photovoltaic array, 7 kW power inverter, 20 units of battery (305 Ah and 6V) and 35 kW wind turbines. The optimized energy system has a cost of energy about $ 0.117/kWh and total net present cost by about $14800. The environmental assessment of the hybrid system shows that the greenhouse gases emissions will reduce about 25ton CO2/year (16968 kg/year) in the local atmosphere.

The welding of metals is one of the most important processes that require high control for obtaining a good quality of weldments. Joining of dissimilar metals is a more complex operation compared to joining of similar metals due to the differences in physical, metallurgical and mechanical properties. In this article, austenitic stainless steel AISI 303 studs were welded to low carbon steel AISI 1008 plate using arc stud welding (ASW) process. An experimental procedure was applied to estimate the effect of welding parameters namely welding current and welding time on microstructure and mechanical properties of the joint. The optical microscope was used to show microstructure properties while both the micro-Vickers Hardness and tensile test were adopted to evaluate the mechanical properties. The results revealed that the presence of carbides at the fusion zone FZ towards AISI 303 leads to the maximum value of hardness (501) HV. The best welding parameters were 600 AMP 0.25 second at which joint tensile strength of 515 MPa was recorded. Welding time was the effective parameter in the ASW process followed by welding current, proper selection of welding time and welding current produces good joint quality

This paper presents an experimental study on the effect of electro-osmosis in improving the properties of gypsum soils. Electro-osmosis is the process of transferring ions from the anode to the cathode by appling an electric field. The experimental model for this study is by preparing a soil sample with dimensions of (30 x 30 x25) cm, and contained a wooden box of (30 x 30 x 30) cm. This box was put in a water tank of (50 x 50 x 35) cm to confine the water. Two types of gypsum soil used in this study are placed inside the wooden box with gypseous content of (30% and 60%). Rectangular plate (5x5) cm with thickness was 3 mm used to simulate a rigid foundation and time-leveling tests were performed for (10) volt model in addition to take reference readings (without applying any voltage for comparison) with change of load applied where its use (20 and 28) T/m2. The variables in this study are gypsum content, time, applied load and corresponding settlement. The results showed a responsed the soil to the electro-osmosis, while noted the improve is occur in the settlement.

The aim of this research is to study the effect of corrugated steel plate strengthening on the structural behavior of reinforced concretebox girder using corrugated steel plates with vertical and horizontal corrugation and studying the effect of the shape of cells using rectangular and circular shape with the same web width and strengthening the circular cell with flat plate. Five simply supported reinforced concrete box girders are casted using Self-compacting concrete and experimentally tested under four-point load. The box girder specimens are divided into two groups according to the steel strengthening and the shape of cells. The experimental results showed that in the first group, the using of the vertical and horizontal corrugated steel plates strengthening increased the ultimate load by (7.14% and 11.03%) respectively compared with the control box girder, and decreased the crack width, the results also showed that in the second group, the using of circular cell and circular strengthened cell increased the ultimate load by (17.85% and 29.22%) respectively compared with the control box girder with rectangular cell and decreased the crackwidth. All the box girders in the first and second group failed with diagonal shear

In order to maximize the thermal efficiency of shell and coil heat exchangers, substantial research has been done and geometrical modification is one way to improve the exchange of thermal energy between two or more fluids. One of the peculiar features of coiled geometry is that the temperature distribution is highly variable along the circumferential section due to the centrifugal force induced in the fluid. Moreover, most researchers are concentrated on using a shell and single helical coil heat exchangerto enhance the heat transfer rate and thermal efficiency at different operating parameters. Therefore, the aim of this study is to investigate temperature variation ((T-1, T-2, T-3 and T-4) across a shell and single/double coil heat exchanger at differentcoil pitches, hot water flow rate, and cold-waterflow rate along the outer surface of the coil using experimental and numerical analysis. For single and double coil heat exchangers, Computational Fluid Dynamics (CFD) is carried out using pure water with a hot water flow rate ranging between 1-2 l/min for the coil side heat exchanger. For single coil heat exchangers, the numerical analysis findings showed a good agreement with experimental four-temperature measurement results (T-1, T-2, T-3 and T-4) with an error rate of 1.80%, 3.05%, 5.34% and 2.17% respectively. Moreover, in the current double coil analysis, the hot outlet temperature decreased by 3.07% compared to a single coil (baseline case) at a 2.5L/min hot water flow rate. In addition, increasing the coil pitch will increase the contact between the hot fluid and the coil at a constant hot water flow rate and thereby decrease the hot fluid outlet temperature. Finally, a computational analysis was carried out to examine the flow structure inside singleand double coil heat exchangers, and the findings indicated that the effect of centrifugal forces in double coil heat exchangers at various coil pitches caused the secondary flow to be substantially reduced.

Although there are several high-capacity screw piles in use currently, there are few studies on their lateral performance. The aim of this study is to investigate the lateral behaviour of several models of screw pile group (1×2), (2×1), and (2×2) embedded in soft clay and extended to stiff clay under lateral static load. Three spacing between pile (1.5, 3, and 4.5) Dh (helix diameter) with a shaft diameter of 10 mm, single and double helix, and embedded length ratio L/d 40 were used. The results showed thatincreasing the number of the piles in the group had a larger effect, the lateral resistance of group (2×2) increase to about (2.5 and 3.2) times more than groups (2×1) and (1×2) respectively. While the increase of pile spacing in the groups from (1.5 Dh) to (3 and 4.5 Dh) increases the lateral resistance about 6-23% and 16-52% respectively. Also, the result showed that the screw pile with double helix gives an increase in lateral resistance about 3-8% from the single helix.

This paper presented an experimental study of the behaviour of wide reinforced concrete beams with different shear spacing and beam width. Eight specimens in two groups, the group one contains four specimens with the dimensions of (200x500x1600mm) and shear reinforcement spacing (d/2, 0.65d, 3/4d and 1.0d), the group two contains four specimens with the dimensions of (200x600x1600mm) and shear reinforcement spacing (d/2, 0.55d, 3/4d and 1.0d), Variables studied in this study shear reinforcement spacingand width of wide beam, the increasing of shear reinforcement spacing gives close results in RC wide beam, increased shear reinforcement spacing decreased the ultimate loud by 6.6% and when increasing width of beam the ultimate loud decreased by 9.5%, The ultimate deflection decreased by 16.5% and when increasing width of beam decreased by 7.2 %,The number of flexural cracks was equal in all beams, when increasing width of beam the number of flexural crack increased by 2 cracks, The average spacing between shear cracks decreased by 7%, when increasing width of beam average spacing between shear cracks decreased by 19%

This paper represents a parametric study utilizing finite element analysis for twenty-five reinforced concrete semi-circular deep beams. The parameters that were taken into consideration in the current work are radius, height, width, concrete compressive strength and number of supports. It is found that decreasing radius of beam by 16-66% leads to decrease the midspan positive moment, support negative moment, torsional moment and midspan deflection by about 0.3-20%, 2.4-25%, 2-24% and 29-85%, respectively, while the load capacity increases by about 23-158%. The midspan positive moment, support negative moment, torsional moment and load capacity increase by about 20-682%, 20-81%, 20-81% and 21-84%, respectively, whereas midspan deflection decreases by 7-17% when the beam height increases by about 16-66%. The positive moment, negative moment, torsional moment and load capacity increases by about 43-197%, 40-185%, 29-187% and 46-214%, respectively, whereas deflection decreases by about 1.4-3.3% when the beam width increases by about 16-66%. The positive moment, negative moment, torsional moment and load capacity increases by about 10-84%, 9-77%, 9-79% and 11-92%, respectively, whereas deflection decreases by about 0.1-0.5% when the compressive strength increases by 20-220%. Finally, it is found that the positive moment increases by about 36-47% when number of supports increased by 33-66%, while the negative moment increases by about 16-31% when number of supports decreases by 14-29%, whereas the torsional moments and deflection decreases by about 6-55% and 37-84%, respectively when number of supports increases by 33-133%, while load capacity increases by 156-969% when number of supports increases by 33-133%.