Materials Engineering and Science

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Authors: Ayad Z. Mohammad
Abstract: Nd:YAG laser was used at different number of shots (300, 500, and 700 pulse) to prepare ZnO:Cu2O nanoparticles at mixing ratios of (0.5, 0.7 and 0.9). The optical, structural, morphological and electrical properties of the prepared films were investigated. The energy band gap was found to be (2.5, 3.2 and 3.53 e.v). The crystalline structure showed no impurity peaks indicating that the final product was free from surface impurities. Also, the materials peaks and intensity is present and well identified as the mixing ratio varies. The AFM results for all ratios indicate that as the number of pulses increase, the higher the resulted grain size. The average grain size was between (58.82 nm) to (95.75nm). The J-V characteristics were measured for the prepared solar cells and it was found that the efficiency varied with the mixing ratio and film thickness from 0.29% to 2.38%. F.F varied from 0.28 to 0.25.
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Authors: Doaa M. Abdullah, Alaa A. Abdul-Hamead, Farhad M. Othman
Abstract: In this Research, a ball mill procedure was used to prepare a nanopowder from a cement dust material supplied by Cement Factory for reinforcing the oil well cement through using it as a partial replacement of oil well cement class G by a weight percentage of (0.25 to 1%) and nanorod ZnO with the same percentages. The mix with a water to cement ratio was kept at 0.44. Characterizations of the structured prepared samples were done, density and compressive strength and free water. Experimental outcomes display that the generated nanopowder have a particle size of (100 nm) and that the structural properties improved significantly with the development phase of calcium silicate hydration C-S-H. Density and compressive strength significantly improved with lower free water. That makes it proper as smart cement for the oil well applications.
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Authors: Sarah M. Taleb, Makram A. Fakhri, Salah Aldeen Adnan
Abstract: The nanocrystalline structure of Lithium niobate (LiNbO3) was prepared and deposited onto substrate made of quartz by utilize pulse laser deposition technique. The effect of substrate temperature on the structural, optical and morphological properties of lithium niobate photonic film grown was studied. The chemical mixture was prepared by mixing the raw material (Li2CO3, Nb2O5) with Ethanol liquid without any further purification, at time of stirrer 3hrs but without heating, then annealing process the formed material at 1000C° for 4hrs. We characterized and analyzed the LiNbO3 nanostructure thin films by utilize Ultra-Violet Visible (UV-vis). The UV-vis measurements show that, when the substrate temperature increases, the values of transmission, absorption and energy band gap will decreased, but the values of reflection and refractive index will increased. That means the LiNbO3 thin film prepared at substrate temperatures 300C° give the best result for manufacture the optical waveguide.
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Authors: Salah Aldeen Adnan, Zainab H. Tawfiq, Makram A. Fakhri
Abstract: The effect of laser wavelength on gold nanoparticle (Au NPs) fabrication is reported by using the laser ablation in the liquid method in the ethanol. The Pulsed Laser ablation in liquid technique of the gold target was ablated using an Nd:YAG laser nanopulsed nanosecond after that the investigation of the gold NPs was tested by the AFM (Atomic Force Microscopy), and the (XRD) X-ray diffraction. The results showed the characteristics of prepared NPs, depending on XRD, AFM. NPs obtained by 532 nm laser possess better properties than that achieved by 1064 nm laser according to the highest intensity of shorter wavelengths.
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Authors: Mariam M. Hassan, Makram A. Fakhri, Salah Aldeen Adnan
Abstract: Porous silicon (n-PS) with diverse morphologies was prepared on silicon (Si) substrate via photo-electrochemical etching technique. We studies the structure, surface morphology, pore diameter, roughness, based on (XRD), (AFM), (SEM) at different etching time (5, 10 min) and current (10mA/cm2).
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Authors: Fahad Mohanad Kadhim, Jumaa Salman Chiad, Maryam Abdul Salam Enad
Abstract: Four prosthetic knee joints (polycentric knee weight activating-4bar and friction, extension assist controlled),(single axis knee weight activating and friction, internal extension assist controlled), (single axis knee weight activating-4bar and hydraulically, controlled) and (polycentric knee geometric locking-6bar, hydraulically controlled) for a trans-femoral patient were tested. The tests were conducted to find the maximum velocity as well as discussing the most comfortable prosthetic forthe patient and walking stability for these prosthetic knees by examining the gait cycle and measuring the ground reaction force (GRF), using force a plate device. Also, the interface pressure was measured between socket and stump muscles by using F-socket device to get the stress distribution during walking with a prosthetic knee. Results manifested that the polycentric knee geometric locking - 6bar, hydraulically controlled is the best because of the good homogenous distribution of GRF between the healthy and prosthetic limb, during which the difference between both the healthy and prosthetic limb is with the least value (4%).And, K4 gives the minimum value of differences in contact pressure between the left and right limb with a value of (24%), it alsoimparts the maximum symmetry between the left and right limb according to the gait cycle parameters.The best results of the interface pressures and kinovea velocity are achieved whenK4 is used with (132.4KPa, 0.71m/s), respectively. Finally, the polycentric knee geometric locking - 6bar, hydraulically controlled is the best according to the ANSYS results during which it yields the minimum values of Von-Mises stress with 14.24MPa and a maximum factor of safety of 3.11.
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Authors: Fahad Mohanad Kadhim, Marfa Salah Hayal
Abstract: This work involved two major parts: the first Part is the experimental part included manufacturing ankle foot orthotics, measure the (the reaction force of the ground, pressure distribution) for both normal (healthy) and sound side (intake) legs in two case, the first measurement when the patient walking without orthosis while the second test when the patient dressed up the flexible (AFO). The pressure generated between leg and calf part is measured by F-Socket devise. The experimental part also consist test the mechanical properties of a suggestion composite material. The second Part is the (FEM) finite element analysis for numerical simulation part during which the stresses are calculated using ANSYS 14.5 software. Experimental work was done on a case study suffering from low level spinal cord trauma he has good control of the trunk muscles but the muscle weakness and nerve damage for right leg. The patient with age, weight of 30years, 75kg, respectively. The Results show the parameters of test for both legs (left and right) in two cases. The results show that the data of the gait cycle in the case of the patient wearing the brace is more acceptable and we notice improvement in the performance of walking steps and reduce the difference between the infected leg and natural and this indicates the good evaluation of this orthosis. Max pressure obtained is 1.53*10^5MPa from F .Socket at calf region .Max stress Calculated at Posterior ankle joint because it is flexible Position The equivalent Von-Mises stress and the safety factor for fatigue of the composite material gave good results this led to the longer life design.
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Authors: Fahad Mohanad Kadhim, Ayad Murad Takhakh, Jumaa Salman Chiad
Abstract: This study deals with evaluation of smart economic transfemral Prosthetic consist of a new design and manufacturing of knee joint and design and manufacture of a simple electronic circuit that is programmed to control the muscle pressure on the sensor during movement and transfer the voltage of force sensor after processing in microcontroller to the electric motor to flexion and extend the knee joint. A number of tests were carried out to evaluate the smart prosthetic. Gait cycle and EMG tests were performed on a patient with amputation above the knee in two cases, the first is when the patient is wearing the traditional limb and the second is when the patient is wearing the smart prosthetic. The results showed that the gait cycle during the wearing of the smart prosthetic is more acceptable, stable and balanced than the case of the traditional prosthetic wear. The results of EMG test showed that muscles need less effort during movement when wearing a smart limb and this indicates that the energy spent is less and thus provide comfort to the patient. The results of the finite element analysis (ANSYS 14.5) of the knee joint confirmed the strength of the joint and its ability to carry high weights for patients.
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Authors: Nisreen Mizher Rahma, Lubna Ghalib, Khalid Mershed Eweed
Abstract: This study presents the experimental results of the influence of mechanical fatigue and tensile on hybrid composite materials. Epoxy with Novolac resin are used as matrix for the reinforced materials that consist of glass fiber type E. The slates made of hybrid composite materials for two proportions (80% epoxy, 20% Novolac) and (60% epoxy, 40% Novolac) were reinforced by three volume fractions (10%, 20% and 30%) of glass fiber type (E), where been manufacturing (6) panels of hybrid composite materials, all these panels cutting into two groups samples with dimension (70x 10) mm in order to execute the fatigue test and (150x20) mm for tensile test, according to the specifications of the device used.The process took place in two stages: The two stages include executing the fatigue and tensile test specimens with a ratio (80% epoxy, 20% Novolac) in the first stage and (60% epoxy, 40% Novolac) in the second stage for the volume fractions (10%, 20% and 30%) of glass fiber type (E) and comparison the results between them for each stage. The results obtained from fatigue test in the first stage showed that the number cycle for fatigue limit decreased when the load and the number of layers of reinforcing are increased. But in the tensile test for the samples the results showed that the value of the elongation increasing to the point of failure when the load increased for the same layers of reinforcement, as well as the value of elongation decreasing to a failure when increased the number of layers of reinforcing glass fibers type (E) for the same load. The results of tensile and fatigue test obtained from the second stage showed similar to the results in the first stage, but the cycle number of fatigue limit less value from the first stage and the stress was higher in the fatigue test. For tensile test the elongation values ??less and the stress values higher for the same volume fraction of the reinforcement due to increase in the proportion of Novolac.
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