Journal of Engineering

The surface roughness of machined parts is a crucial parameter in predicting the performance of mechanical components. Predicting optimal machining parameters is essential for cost reduction and achieving desired surface quality. This study investigates the effects of depth of cut, spindle speed, and feed rate on the surface roughness of milled aluminum alloy AA6061. Experiments were conducted using a manual milling machine with a coated carbide cutter, arranged according to the Taguchi L9 orthogonal array method. Average surface roughness (Ra) was measured, converted to signal-to-noise (S/N) ratios, and analyzed using analysis of variance (ANOVA). The optimal parameters were found to be a spindle speed of 2400 rpm, feed rate of 30 mm/min, and depth of cut of 0.5 mm. ANOVA results indicated that spindle speed was the most influential parameter, accounting for 66.42% of the variance, while depth of cut had the least influence at 5.34%. Higher spindle speeds improved surface quality, while lower depth of cut and feed rates were preferable.

The key benefits connected with Roller-Compacted Concrete Pavement (RCCP) technology are costs reduction of life-cycle, shrinkage decrease, opening to traffic at an earlier time, and a cooling of the city's core area. This technology received much consideration recently for applications in highway tenders. Several attempts worked on instilling sustainable implementation in RCCP using alternate materials. This work presented a thorough review of the literature on alternative materials for RCCP published between 1997 and 2021. Recycled concrete and asphalt pavement aggregates are two examples of alternative materials to traditional quarry rock that have been studied. Critical evaluations of the mechanical properties of RCCP have been used to assess these alternative aggregates' potential. This article explains how the basic properties of the materials impact the RCCP's behavior. The results of a comprehensive study into utilizing the substitute aggregates in manufacturing RCCPs showed the best mix ratios for attaining long-term sustainability, along with identifying potential future study topics. This research additionally indicates several knowledge gaps that can only be filled by further research and experimentation.

Engineering design relies highly on the selection of suitable materials. Because there are many engineering materials, selecting a suitable material for a product requires a systematic selection approach. This paper provides a hybrid strategy for choosing the best material for an engineering design to give the best performance at the lowest cost based on Ashby's performance indices. Then, it ranks the result by the grey relational approach integrated with the Weighted Entropy Method to choose the optimum material for the main rotor blade of a helicopter. Different materials used for manufacturing rotor blades, such as Aluminium alloys, titanium alloys, steel, composites, and wood, have been discussed. The performance indices chosen are stiffness, strength, and fracture toughness. The performance indices proved that the composite material has excellent structural strength, stiffness, and toughness. The result shows that CFRP is the best material for manufacturing helicopter rotors, while wood and steel were the best and cheapest when the design had to be economical.

No-fines Concrete is a lightweight porous concrete produced by omitting sand from the traditional concrete mix. It helps replenish the groundwater aquifer by directly allowing precipitation to seep into the earth thanks to its wide pores. This work studied the influence of partially replacing cement with silica fume (SF) with percentages of 5, 8, and 10% on some properties of no-fine concrete made using recycled coarse aggregate. The natural coarse aggregate (NA) was replaced with 10%, 20%, and 30% by crushed reactive powder concrete waste volume as recycled aggregate (RA). The optimum percentage was 10% RA with 10% SF, which indicated a substantial improvement in the no-fine concrete's strength, dry density, and water absorption compared to the design mix. The results exhibit increases in percentages in compressive strength, tensile strength, flexural strength, and dry density by 18%, 14%, 16%, and 1%, respectively, while exhibiting a decrease in water absorption by 5% at 28 days.

The disconnected piled raft foundation (DCPRF) is one of the newly introduced foundations for specialization in geotechnical engineering, which significantly reduces the moment and stress on the pile head. In addition, this type of foundation is an ideal choice in areas with seismic activity due to the presence of cushion material between the raft and the piles. This work aims to present a numerical model in PLAXIS 3D software for connected piled raft and disconnected piled raft foundations under the influence of seismic loads and investigate the effect of pore water pressure on the disconnected foundation compared to the connected foundation. The study will depend on the earthquake that struck Iraq in November 2017 in the Halabja region. Strength was 7.3 on the Richter scale with PGA (0.1g). The results of changing pore water pressure showed the variation of pore water pressure. In the case of a DCPRF, the porewater pressure and excess porewater pressure in the soil are much greater than in the case of a CPRF. The increase in the porewater pressure is due to the weight of the building and the weight of the additional cushion layer on the soil. The mechanism for transferring the load in the case of a DCPRF is carried out by raft, then to the cushion, and then to the soil and piles. The load transferred to the soil in the case of DCPRF is more than that transferred to the soil in the CPRF system.

Unconventional reservoirs are distributed over a broad area and only generate commercial quantities of hydrocarbon using specialized technology. Tight reservoirs are reservoirs with permeability less than 0.1md. One of the leading oil fields in Iraq is Halfaya field. The tight reservoir is Saadi. It is a carbonate reservoir with poor petrophysical characteristics, moderate pores, and limited pore throats, so production from these reservoirs require hydraulic fracturing. The hydraulic fracturing can be carried out using fracturing fluid. The selection of fracturing fluids should be selected as the first step in fracturing design. The objective of this research is to find out the effect of fracturing fluids on the shape of the fracture formed. Three designs were constructed based on the fracturing fluids used to build fracturing models, where three kinds of fracturing fluids were used slickwater, guar, and hybrid (combination of slickwater and guar) with a pump rate 31.5 bpm. In the first design, the fracture's height extends up and down the Saadi formation due to the presence of fragile layers around Saadi formation, so fluids are produced from these three formations. In the second design, the fracture's height is limited within the Saadi formation from the top but extends to the Tanuma from below, and therefore the production will be from the Saadi and Tanuma reservoirs. Three hybrid treatments were analysed: 30% guar & 70% slickwater, 50% guar & 50% slickwater, and 70% guar & 30% slickwater. The results show that the third design (50% guar & 50% slickwater) give the best oil production and NPV.

n civil engineering, there are many problems related to the transmission of pressure waves through the soil due to dynamic loads. In industrial applications, these vibrations are often caused by the impact of weights on the foundation machine. Typically, these basics transmit effective vertical stresses to the surface layers. Accordingly, the dynamic performance of natural clay soils under the influence of individual active loads was carefully studied in this work. A deflection scale system dropped different loads from several elevations. The application of this research was to study the surface soil responses only. These responses include the vertical displacements, velocities, and accelerations implied by impacts on the soil surface. Some of the results showed a decrease in the displacement value of the natural clay soil by a rate ranging from 25% to 35%, a result of an increase in the overburden pressure based on an increase in the embedment depth, which led to a rise in the stiffness of the clayey soil.

Cell-free massive multiple-input multiple-output (CF-MIMO) system has been considered a promising technology for 5G and 6G networks for its ability to handle the rise in demand effectively. With CF-MIMO, improved energy efficiency can be obtained from straightforward signal processing. One of the potential problems in CF-MIMO systems is high power consumption due to the large numbers of distributed Access Points (APs), which decrease energy efficiency. This research proposes a modified algorithm to improve overall energy efficiency by reducing total power consumption via using the APs selection technique while maintaining the system's sum of rate. The technique used for APs selection is the largest large-scale-based selection, where each user is served by a subset of APs that offer the best channel condition rather than by all of APs. Total energy efficiency has been calculated for three cases: without APs selection, fixed APs selection, and dynamic APs selection (proposed approach). The simulation result shows that the proposed approach significantly improves energy efficiency by 45% at the signal-to-noise ratio (SNR) equal to 6 dB than the case where the selection of APs is fixed due to the optimal APs selection for each user.

Recently, some of Iraq's newly constructed asphalt concrete pavements showed premature failures with significant negative impacts on roadway safety and the economy. Using Nano hydrated lime (NHL) in pavement construction could be one of the possible steps to improve pavement durability. This article discusses how NHL affects the durability of hot mix asphalt. NHL was added in two methods to the asphalt concrete mixture for the wearing course. The first is the dry method, i.e., on the aggregate, whereas the second is the wet addition method, i.e., to the bitumen. The percentages were tried for each additional method; 1, 2, and 3% by weight of aggregate for the dry method and 0.5, 1, and 1.5% by weight of asphalt concrete for the wet method. The optimum asphalt cement contents were evaluated using the Marshall procedure. Asphalt concrete mixes were prepared at their optimum asphalt content and then tested to evaluate their durability properties, including moisture damage and permanent deformation. These properties have been evaluated using indirect tensile strength and uniaxial repeated loading tests. The results show that the NHL has improved the permanent deformation characteristics and resistance to moisture susceptibility.

The primary goal of this investigation is to study the effect of using mono and hybrid fibers on the fresh and hardened characteristics of Lightweight Self-Compacting Concrete (LWSCC). Slump flow test, L-box test, sieve segregation test, and V-funnel test were used to evaluate the workability of LWSCC. The mechanical characteristics of LWSCC were assessed by using compressive strength, splitting strength, and flexural strength. Four mixtures using two types of fiber: Steel fiber (St) and polypropylene fiber (PP) (0% fiber, 1% (St), 0.75% (St) + 0.25% (PP), 0.5% (St) + 0.5% (PP)) were made. According to the results, (St) fiber and hybrid fiber addition to LWSCC reduced its workability, although the values of tests were still within the acceptable range standard of EFNARC. The findings indicated a decrease in the values of slump flow and L-box test by adding mono and hybrid fibers to the LWSCC mixture. While the T500mm and V-funnel tests increased by adding mono and hybrid fibers to LWSCC mixture. The results also indicate that the utilization of (St) fiber and hybrid fibers had a significant effect on the mechanical characteristics of LWSCC. Where the flexural and splitting strengths significantly increase with the addition of (St) and hybrid fibers to the LWSCC mix.