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Aims and Scope
Editorial Board

1. Analysis of ultrasonic peening mechanical properties and fatigue damage of 2017A-T3 Aluminum alloy

Alalkawi H.J.M¹, Elkhawad Ali Elfaki², Ali Yousuf Khenyab²

1 University of Technology, Electromechanical Engineering Department, Baghdad, Iraq.
2 Sudan University of Science and Technology, Sudan.

Abstract: Mechanical surface treatment like laser peening (LP), shot peening (SP) and ultrasonic peening (UP) are used to enhance the mechanical and fatigue material properties. In the current work, ultrasonic peening (UP) technique has been selected used to surface treatment of 2017A-T3 Al-alloy so as to enhance the mechanical and fatigue properties of the these alloy. Mechanical properties and constant fatigue testes has been performed at room temperature (RT) and stress ratio R= -1. Three type of UP surface treatment were done, i-e one line (1UP), two lines (2UP) and three lines (3UP) at surface test specimens. The experimental analysis of results indicated that, all the above three types of UP improved the mechanical properties i-e σ_u and σ_y by 10,3%, 30.7% increase for 1UP, 9.4%, 29.6% for 2UP and 6.6%, 27% for 3UP respectively. But the best enhancement was obtained for the (1UP).Fatigue at constant amplitude tests has also done for the above three types and compared to the unpeened one. The results showed that the (1UP) is better for fatigue life improvement; it is 160% at load 200 MPa and 180% at load 175 MPa respectively.

Volume 8, Issue 6, 2017, pp.457-464.

2. Mechanical characterization of micro and nano alumina-Aluminum composites produced by powder metallurgy process

Abdulrahman Abed Najim, Ban Ali Sabri

Al-Nahrain University, College of Engineering, Mechanical Engineering department, Baghdad, Iraq.

Abstract: Aluminum metal obtained great attention in the new era. It’s a wide usage in automotive industries and airplanes. Also, Aluminum metal can be used for improving the mechanical properties and an intension to overcome the basic lack of aluminum/aluminum alloy which is low wear resistance are nowadays ambition. Micro sized alumina is an elderly major reinforcement additive while, the nano sized Al2O3 phase is recently used and studying its effects on aluminum properties which are still in need for more study. A trend has been observed in the field of aluminum based composite to employ alumina phases in micro and nano for creating composites of unique properties. A process of powder metallurgy technique has been used to fabricate, respectively, composites with an alpha micro (30 µm) and gamma nano (20 nm) sized alumina reinforcing aluminum metal matrix of 45 µm size. Also, the weight percentages of the reinforcement materials used were (5, 10 and 15wt %). Specimens have been manufactured according to ASTM standards. After the mixing of powder, the green samples have been obtained from cold axial pressing under a compaction pressure of 500MPa and sintered under 500ºC for two hours in a vacuumed pressure less tube furnace. Results revealed that as the amount of Al2O3 content increases, the hardness, wear resistance of the micro and nanocomposites increases significantly. Compressive strength in both of micro and nanocomposites records its maximum amount within an additive of 10wt %. Upon a comparison of the mechanical properties for the overall percentages of micro and nano composites. Nano composites presented higher wear resistance, hardness and compressive strength superior than the micro composites. As a general indication, addition of alumina reinforcement contributed in improving the mechanical properties of the pure aluminum matrix. While the nano alumina provides higher performance in the improvement of mechanical properties.

3. Closed-form solution for evaluating the principal instability regions for conservative pipes conveying pulsating flowing fluid

Albert E. Yousif¹, Muhsin J. Jweeg², Mahmud R. Ismail¹

1 Al-Nahrain University, College of Engineering, Mechanical Engineering department, Baghdad, Iraq.
2 University of Telafer, College of Engineering, Iraq.

Abstract: The dynamical behaviors of pipes containing pulsating fluids are nonlinear. In such nonlinear systems principal regions of dynamical instability can result from the effect of the periodic excitation of the fluctuated fluid flow. Evaluating the boundary frequencies for these types of instabilities had been carried out by many analytical and numerical methods. In this paper, an approximate “closed-form” solution for evaluating the principal boundary regions of instability for conservative pipes conveying pulsated fluid has been attempted. Bolotin's method was employed to split the boundaries from the stable regions. The resulting coupled-ordinary differential equations is decoupled by neglecting the effect of the mass ratio term and solved analytically. After imposing the specified boundary conditions, then the simplified formulas or transcendental equations were obtained for the pipes under consideration. These equations can give the principal boundary regions in term of the system parameters by simple calculations. The present solution was carefully checked with the "exact" solution where the mass ratio was included. The results showed good agreement for pinned-pinned clamped-pinned and clamped-clamped pipes conveying pulsating fluid.

4. The effect of ultraviolet radiation on the modulus of stress relaxation of polypropylene prosthetic sockets

Kadhim K. Resan

Materials Engineering Department, Faculty of Engineering, Al-Mustansiriyah University, Baghdad, Iraq.

Abstract: In some countries such as Iraq, the high temperature and high exposure to ultraviolet (UV) rays in summer, result in changes to the mechanical and physical properties of polypropylene sockets. In this study four groups of sockets were exposed to ultraviolet rays for different periods of time: zero, 20 hours, 40 hours and 60 hours. Also, the stress relaxation modulus was measured for these groups at 50 oC. Also, the effect of ultraviolet on the stress relaxation modulus, tensile strength, hardness and morphology of polypropylene is determined. The interface pressure is measured between the prosthetic below the knee socket and stump by f-socket sensors and then this socket is modeled by ANSYS 15 Workbench, from results the stress relaxation modulus decreases with increasing UV exposure time and temperature. As a result of high temperature and high exposure of ultraviolet (UV) ray in summer in some countries such as (Iraq), the mechanical and physical properties of polypropylene socket are changed. In this study there a four groups of polypropylene were exposure by ultraviolet ray at different time, zero, 20 hours, 40 hours and 60 hours .Also, the stress relaxation modulus was measured for these groups at 50 OC. So the main aim of this study is to find the effect of ultraviolet on the stress relaxation modulus, tensile strength, hardness and morphology of polypropylene .The interface pressure is measured between the prosthetic below the knee socket and stump by f-socket sensors then modeling this socket by workbench ANSYS 15. The ultimate stresses are decreasing with time and the hardness are alternative value, it is decreasing at 20 hours exposure UV and then increasing at 40 hours and 60 hours . The modulus of stress relaxation at not exposure specimen down a lot compared with the other groups this behavior led to deflection of socket is increasing.

5. Identification of complicated structure by using MATLAB; a case study on crankshaft

Mahmud Rasheed Ismail, Imad Zuhair Ghani

Mechanical Engineering Department, Al- Nahrain University, Baghdad, Iraq.

Abstract: In MATLAB System Identification SID refers to the method for estimating the system transfer function from experimental tests by using computer software so in this work the SID method is employed for analyzing practical structure for crankshaft. The validity of this method is firstly checked by applying it on beam model under boundary condition (simply support) where the required parameters for this simple system are evaluated in two ways. First theoretically by using Modal analysis approach and second experimentally by using SID method. From comparing the results, it is found that; the accuracy of using SID method is within acceptable limits, where the error is not exceeded 6.7% for case of simply support. Then the method is extended for using for the crank shaft it is found that the transfer function parameters at the mid-section are increased as compared with the crank ends.

6. Investigation of nano-alumina on some mechanical and morphological properties of unsaturated polyester

Zahraa T. Khamees, Khalid M. Oweed

College of Engineering, Al-Mustansiriya University, Baghdad, Iraq.

Abstract: The objective of this research to investigate the influence of adding nano (Al2O3) on some mechanical properties of unsaturated polyester based resin (UP) by adopting two different mixing methods. Different weight fractions (0, 0.5, 1, 1.5 and 2) wt% of nano (Al2O3) was used to reinforce the UP by using two mixing methods; shaker mixing method (SM) and mechanical mixing method (MM). The mechanical properties of both control and polymeric nanocomposites (compressive strength, and flexural strength) were evaluated. The results showed that higher enhancement in these characteristics were demonstrated for samples with 2 wt% and 1.5wt% of nano (Al2O3), these enhancements were 26.84% and 23.33%, when SM and MM were used, respectively. Regarding flexural strength, an increment of 93.22% was recorded for samples with 2 wt% for SM when compared with MM and pure UP samples. Finally, SEM micrographs approve that equal dispersion of nanoparticles progress the mechanical features of PNCs.

7. Investigation the properties of hip implantation structure based on nanotechnology by using radio frequency magnetron sputtering

Dunya Abdulsahib Hamdi^1,2

1 Department of Prosthetics & Othotics Engineering Department, Al Nahrain University, Baghdad, Iraq.
2 Surface Analysis and Materials Engineering Research Group, School of Engineering and Information Technology, Murdoch University, Murdoch, WA 6150, Australia.

Abstract: In this research, radio frequency magnetron sputtering was used to prepare the Ti6Al4V alloy by powder ceramic Alumina (Al2O3 has 1um particle size, alpha phase, with purity is 5N (99.999%)) in order to increasing biocompatibility surface alloy. Energy Dispersive X-ray spectroscopy, X-ray diffraction, Scanning Electron Microscopic and Optical microscope were performed to identify phases and microstructure. In vitro studies were carried out in simulated body fluid and HP 7.4 with biomimetic tests to see the efficiency of the biocompatibility of the coated surface. Energy Dispersive X-ray spectroscopy chemical analysis showed increasing in Al2O3 and a reduction in Ti content with increasing time deposition. X-ray diffraction phase analysis agreement with Energy Dispersive X-ray spectroscopy results, increasing intensity phase (110) and crystalline with heat treatment at 500ᵒC. The Al2O3 phase disappeared after immersed and Hydroxyapatite (HAp) phase is very visible with full coated covered the surface with high intensity (002) and (211). Scanning Electron Microscopic showed the Al2O3 good coating and there is no crack appearing with convert particle size to 50nm by using radio frequency sputtering, HAp coated all the surface with particle size 300nm after immersion in SBF that is mean the surfaces is biocompatibility and this confirm by Optical microscopy, according to the result the coating will be compatible with human tissue.

8. Natural frequency response to the angle and size of oblique crack in an isotropic hyper composite beam

Alaa Abdulzahra Deli

University of Kufa, Engineering Faculty, Mechanical Engineering Department, Iraq.

Abstract: The present work investigates beam natural frequency that includes the effect of oblique crack damage with variable parameters such as crack size and location. This study was investigated both numerically and experimentally. The predicted results were compared to the measured data, where a good agreement has been observed. The beam natural frequency is evaluated for beam composite materials compound from polyester resin materials reinforced with two materials, which are glass short fiber and glass powder. The natural frequency is evaluated for different design parameters, which for composite material are the volume fractions of resin, fiber, and powder; while for crack effect they are the location, size, and orientation of the crack. The experimental results of natural frequency were evaluated through manufacturing composite beam samples, forming crack on it, testing it with vibration machine to measure the natural frequency. To numerically predict the natural frequency, tensile test samples of composite materials are manufactured firstly and then tested by tensile machine to find their mechanical properties, which are required as input data to the ANSYS Mechanical APDL commercial code. The natural frequency comparison has shown that the maximum error between the experimental and numerical data does not exceed 10.63%. The results reveals that increasing the crack orientation results in an enhancement in the natural frequency due to the reduction in the vertical crack component, while the increase in the crack size and location causes a decrease in the natural frequencies.

9. An analytical approach for evaluating the flutter instability boundaries for cantilever pipes conveying fluid

Albert E. Yousif¹, Muhsin J. Jweeg², Mahmud R. Ismail¹

1 College of Engineering, Al-Nahrain University, Baghdad, Iraq.
2 College of Engineering, Telafer University, Baghdad, Iraq.

Abstract: A new approach for evaluating the flutter instability boundaries based on the analytical solution of the equation of motion of cantilever pipes conveying fluid has been attempted. This approach leads to a simple transcendental equations form which the critical speed of flutter instability and the associated natural frequencies of cantilever pipes can be determined for any pipe parameters. The stability and critical natural frequencies maps can be simply constructed. The results of the presented approach are carefully checked with published results. The presented results showed very good agreements.

10. Study of erosion-corrosion and electrochemical corrosion in some Aluminum alloys (Al 2024T3 and Al 7075T6)

Muna Khethier Abbass¹, Shireen Amin Abdulrahman², Hussein Mousa Habeeb³

1 Department of Production Engineering and Metallurgy, University of Technology, Baghdad, Iraq.
2 Mechanical Engineering Department, Engineering College, University of Salahaddin -Arbil, Iraq.
3 Mechanical Engineering Department, Faculty of Engineering, Kufa University, Najaf- Iraq.

Abstract: In this research comparative study between the electrochemical corrosion and erosion-corrosion for two high strengthened aluminum alloys (Al 2024T3 and Al7075T6) was investigated. First corrosion test was performed in seawater (3.5%NaCl solution) using a Tafel extrapolation method and cyclic potentio dynamic polarization tests While the second erosion-corrosion test was carried out in slurry solution (1wt% SiO2 sand in 3.5wt% NaCl solution as the erodent),with varying impact angles (30°, 45° and 90°). It was found that the corrosion rate of Al7075T6 alloy was lower than those of Al2024T3 alloy in case of Tafel extrapolation for polarization test. It was shown that the weight loss rate or erosion- corrosion rate in (gmd) unit for Al7075T6 was lower than that of Al2024T3 at all impact angles during the erosion-corrosion test.

11. Effect of nano-lubrication on the dynamic coefficients of worn journal bearing

Bassim A. Abass, Amal K. A.

Department of Mechanical Engineering, Babylon University, Iraq.

Abstract: In this paper, the effect of Nano-lubrication on the dynamic coefficients of worn journal bearing has been studied. The analytical solution of time dependent Reynolds equation for short journal bearing (L/D<1) is presented to determine the dynamic coefficients of fluid film journal bearings. Dufrane wear model has been adopted to include the effect of worn geometry on the oil film thickness. Modified Krieger-Dougherty viscosity model have been employed to predict the relative viscosities of Nano-lubricant. The results show that the cross coupled stiffness coefficients Kxy decreases by 34% for a worn journal bearing with wear depth parameter of 0.2 while the damping coefficients Cxx and Cyy decrease by 9% and 13%.

12. Improvement the mechanical and thermal properties of hyper composite materials

Mohsin Abdullah Al-Shammari, Sahar Emad Abdullah

University of Baghdad, Engineering Faculty, Mechanical Engineering Department, Baghdad, Iraq.

Abstract: In this work; the reinforcement of polyester resin material is conducted with two types, fiber reinforcement and powder reinforcement to produce an isotropic hyper composite materials composed of polyester resin, carbon powder and carbon or glass fibers with different volume fractions. Several tests were achieved to evaluate the mechanical and thermal properties of the manufactured specimens. The effect of adding powder on these properties and the influence of temperature on the modulus of elasticity are studied. The results showed that the modulus of elasticity, thermal conductivity and thermal effusively are increased with increasing volume fraction of carbon powder. It was observed that the hybridization improves the properties of composite materials at a specific volume fraction of carbon powder. The best mechanical and thermal properties for the materials reinforced with glass fibers was occurred in the specimen composed of 50% polyester, 30% glass fibers and 20% carbon powder, while for the material reinforced with carbon fibers it was occurred in the specimen composed of 60% polyester, 30% carbon fibers and 10% carbon powder.