Cover

Aims and Scope
Editorial Board

1. Characterization of materials used in manufacturing the ankle foot ortheses

Ayad M. Takhakh¹, Muhsin J. Jweeg², S. M. Abbas¹

1Mechanical Engineering Department, College of Engineering, Alnahrain University, Baghdad, Iraq.

2College of Engineering, Telafer University, Baghdad, Iraq.

Abstract: This work covered the experimental program to obtain the mechanical properties of the ankle Foot Ortheses (AFO) composite materials by using tensile, flexural and fatigue tests. They are composed of number of layers (12 layers) perlon with two lyers of carbon-fiber and (10 layers) without carbon fiber. Also, the Ground Reaction Force (GRF), Center of Pressure (COP) and pressure distribution were determined experimentally for patients (first is about (42)year old with height (173cm) and weight(82kg) and the second about (10) years old with height (130cm) and weight (23 kg)) with and without AFO. The results showed that the ultimate stress for perlon 31 MPa, for perlon with carbon fiber of matrix (80:20) 36MPa and perlon with carbon fiber of matrix C-orthocryl 55 MPa. The Fatigue life equation for perlon is 33.64(Nf)-0.30 and for perlon with carbon fiber 60.98(Nf)-0.33. The fatigue limit for perlon is 16MPa and for perlon with carbon fiber 28MPa. The GRF data were measured by using force plate and the pressure distribution are obtained by using F-socket. The gait velocity without AFO equal to 0.43m/sec and with lamination AFO equal to 0.607 m/sec for patient 1 and gait velocity without AFO equal to 0.697m/sec and with lamination AFO equal to 0.837m/sec. The gait cycle time for patients without AFO equals to 42.6% but when wearingAFO equals to 97%.The interface pressure between leg and AFO is measured for AFO surface area by using F- socket sensor reaches 72 MPa and may reach more than this value at the moment of toe off due to the foot drop. The numerical results were obtained by employing the finite element method using ANSYS 15 package using the measured pressure loading and investigating many models to calculate the Von Mises stress and the fatigue safety factor.The fatigue safety factor was found for composite materials AFO with carbon fiber (3.0321), without carbon fiber (1.7578).

Volume 8, Issue 4, 2017, pp.291-298.

2. The effect of wet shot peening on thermal fatigue properties of 2017-t4 aluminum alloy

Hussain J. Mohammed Al-Alkawi¹, Raad M. Fenjan², Samar K. Abdul-Zahraa²

1 College of Engineering, University of Technology, Baghdad, Iraq.

2 College of Engineering, AL-Mustansiriya University, Baghdad, Iraq.

Abstract: In this work, constant and increasing temperature fatigue interaction effect on fatigue behavior of 2017-T4 aluminum alloy was investigated and the effect of wet shot peening on this alloy was also studied. Fatigue tests at constant load constant temperature and constant load increasing temperature were performed. The constant temperatures were RT (25 ̊C) and 100 ̊C. While the increasing temperatures were RT, 50 ̊C, 100 ̊C and 150 ̊C for one test program. The constant fatigue properties of the increasing temperatures were observed the worst case compared to the others constant fatigue properties. Fatigue strength at 100 ̊C was reduced by 10.43 % compared to (RT) fatigue strength, while the wet shot peening (WSP) reduced the above reduction percentage from 10.43 % to 8.69 % i-e an improvement of about 2% was observed Shot peening constant fatigue constant temperature (100 ̊C) revealed that an improvement in the fatigue properties was obtained i-e fatigue life by 1.94 % and fatigue strength by about 2 %.

3. Elevated temperature fatigue S-N curve behavior for three different carbon percentage steel alloys

Hussain J. Mohammed Al-Alkawi¹,Mohammed H. Ali², ShaimaaGhazy Mezban²

1 University of Technology, Electromechanical Engineering Department, Baghdad, Iraq.

2 University of Al-Mustansiriya, Collage of Engineering, Material Engineering Department,Baghdad, Iraq.

Abstract: Constant Fatigue life analysis was done to predict the fatigue life of carbon steel alloy specimens with three different content of carbon (0.758%C, 0.539%C and 0.319%C) under effect of temperature. The fatigue experiments were performed at room temperature (RT) and 100°C with the frequency of 23.34 Hz on a cantilever rotating bending fatigue testing machine. Constant amplitude fatigue test results at room temperature were compared with the fatigue test results at high temperature. The results showed that the fatigue life and fatigue strength decrease at elevated temperature (100°C) as compared to room temperature. Carbon content also had a great effect on fatigue properties in which increasing carbon percentage led to improve the fatigue strength and life up to 0.539%C, but fatigue properties decreased when carbon content exceeded that value.

4. An experimental fatigue study under condition where cyclic corrosion-fatigue interaction occurs

Firas Ali Jasim Al-Mahaweeli¹, Saad A. Khuder Alsaraf²,HussainJasim Mohammed Al-Alkawi³

1 Ministry of Communication, ITPC, Baghdad.

2 Ministry of Education, Baghdad.

3 University of Technology, Electromechanical Engineering Department, Baghdad.

Abstract: Fatigue caused under corrosive environment is termed as corrosion fatigue. Corrosion fatigue occurs by the combined actions of cyclic loading and a corrosive environment. Attempts have been made to investigate the influence of different corrosive media on fatigue behaviour of 7075-T6 aluminium alloy immersed for 100 days in the corrosive media. Corrosion fatigue tests have been conducted using rotating bending stresses and controlling the stress at stress ratio R= -1 and room temperature (RT).The corrosive media used in this study were Shatt - Arab water (Sh. A. W.) at (100 fungi colonies). The results indicated that fungi colonies have significant effect on the fatigue strength. And life reduction of fatigue strength at 10e7 cycles for specimens corroded with (Sh.A.W.) at (100 fungi colonies) was 15% compared with dry fatigue strength. The corrosion fatigue lire's under all stress levels were reduced compared to dry fatigue.

5. Effect of Henna(Lawsoniainermis) concentration on mild steel corrosion

Sahib Mohammed Mahdi

Materials Engineering Department, Al-Mustansiriya University, Baghdad, Iraq.

Abstract: This research was done by using varied concentrations (10,20 and 30 gm/l) of Henna(H) added to 5%HCl, for different exposure times (1, 24, 168,336 and 504 hrs), by using electrochemical test. Tafel curves have been recorded of Henna soaking in 5%HCl. The pH values of medium solutions after each test had be record too. The results shows that each concentration of Henna added to 5%HCl has its own behavior, although they are reduce corrosion rate of the mild steel. The concentration with (30gm/l) of Henna was the favorable effect.

6. Enhancement of the mechanical properties for above-knee prosthetic socket by using the bamboo fiber

Jumaa Salman Chiad¹, Muhammad Safa al-Din Tahir²

1 Al-Nahrain University, College of Engineering, Prosthesis and Orthotics Engineering Department, Baghdad, Iraq.

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

Abstract: Researches specialized in manufacturing of prostheses showed a major development in improving the mechanical and physical properties in the trend to get the best mechanical specifications, lighter in weight, lower cost and ease of manufacturing. For this purpose this research includes manufacture of above the knee  prosthetic socket of lamination of four layers consisting of (1 bamboo 2 fiber carbon 1 bamboo) instead of lamination of ten layers which consist of (4 perlon 2 fiber carbon 4 perlon) which is most commonly used in the manufacture of prosthetic socket at the moment. Tensile test and fatigue test were conducted, as well as interference testing pressure between the residual limb of leg of the patient with socket by device F-Socket to use these pressures later as boundary condition in the simulation program ANSYS 14.5, which will simulate the distribution of Von-Mises stresses, values of deformation and the factor of safety for both available and proposed sockets. The results revealed an increase in the values of each of the yield stress and tensile stress Young's modulusand stress endurance by 20.1%, 162.7% 0.80% 0.241%, respectively, as the results of the prosthetic socket simulations manifested increase in safety factor from 0.998 to 3.85 and decrease in the highest amount of deformation from 10 mm to 5.5 mm.

7. Effect of environment on torsional fatigue test of composite material

Fadhel Abbas Abdullah

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

Abstract: The effect of environments on natural composite materials specimens (polyester and peel of egg reinforcement) with 43% volume fraction in torsion test was investigated. A torsional fatigue system has been designed and manufactured; also the effect of three parameters temperature, relative humidity and twisted angle on number of cycle to failure was studied. Special mechanism to get alternating rotation from a motor that rotates in one direction was manufacturing. The twisted angles of rotation were (25o, 15o, 12.5o, 10o, 6o, 4.5o, and 3o). The heat treatment and relative humidity used in this work are (T=27Co, T=48Co, and T=67Co) and (40%, 60%, and 75%) respectively. The results showed that the major parameter that effected on the number of cycle to failure of torsion fatigue test for composite materials was the angle of twist which decreases the number of cycle when it increases. Also, the increasing temperature and relative humidity conditions caused reduction in cycle number of failure where the maximum reduction of cycles for the specimen occurred at (T=48Co, and relative humidity= 75%).

8. Manufacturing, testing, and numerical modeling a lower limb orthosis for a patient that has a partial foot amputation

Ayad Murad Takhakh, Hassanein Salih Hussain

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

Abstract: This study includes two main parts: The first part includes the process of manufacturing and testing partial foot orthosis for a patient suffering from partial foot amputation. The orthosis was manufactured from lamination Perlon-Carbon-Perlon(4-2-4) and then tested with Force plate and F-Socket. The patientwas tested in two cases: the first without wearing the orthosis and the second after wearing the orthosis. The results of gait cycle testshow that the gait cycle of the patient was improved dramatically after wearing the orthosis as compared with his state without wearing the orthotic. The second part of the research involves the analysis of orthosis for all types ofused materials by using the engineering analysis program (ANSYS V.15). A model of the manufactured orthosis was designed, the safety factor of fatigue and total deformation were calculated. The results of engineering analysis show the difference in safety factor between the plastic and composite materials which has a value of (4.327) in Perlon-Carbon-Prelon (4-2-4) and (4.757) in Hybrid Carbon fiber – Glass fiber, while in plastics was (1.946) in Polypropylene and (1.297) in Polyethylene. The total deformation in composite materials was much less than the plastic materials. Also the results show that Perlon-Carbon-Prelon (4-2-4) decreases in a percentage of (56.4 and 36.6) % as compared with Polypropylene and Polyethylene respectively. While Hybrid Carbon fiber – Glass fiber decreases in a percentage of (66.8 and 51.8) % as compared with Polypropylene and Polyethylene respectively.

9. Fatigue characteristics of patellar tendon bearing orthosis reinforcement materials

Muhsin J. Jweeg¹, Mohanad Al-Asady²

1 College of Engineering, Telafer University, Baghdad, Iraq.

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

Abstract: In this work, two types of composite materials were used to enhancement Patellar tendon Bearing Ortheses where they are fabricated from resin 80-20 as a matrix material, Perlon, Fibers of glass and carbon as a reinforced materials. The mixing of the fibers of class and carbon together in texture way to made with resin to form a hybrid material, A vacuum molding technique was used to made two type of composite materials, the first one is made from (10 Hybrid layer) and the second is made from (3 Perlon + 2 Hybrid + 3 Perlon) layers, tensile and fatigue properties were studied experimentally, theoretically and by using Ansys ver.15 package. It was found that the composite has the highest safety factor failure index and lower deformation level compare to the polypropylene results in a best candidate to give better fatigue characteristics of Patellar Tendon Bearing Ortheses.