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Aims and Scope
Editorial Board

1. Analytical investigation of crack depth and position effect onto beam force vibration response with various harmonic frequency influence

Diyaa H. J. Al-Zubaidi¹, Muhannad Al-Waily², Emad Q. Hussein¹

1 University of Kerbala, Faculty of Engineering, Mechanical Engineering Department, Iraq.

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

Abstract: The crack defect one of important parameters lead to failure the structure, then, it was necessary investigation the crack effect of the dynamic characterization of beam structure applied to harmonic load. So, in this paper investigation the effect of crack depth and location on the beam deflection response applied to harmonic load with various effect of load frequency influence. Therefore, the investigation included derive the general equation of motion for beam applied to harmonic load with crack effect, and then, solving it equation analytically to calculate the natural frequency and beam response with harmonic load effect. In addition, used numerical technique, by using finite element method, to calculate the dynamic characterizations for beam with cack effect and comparison results by analytical results calculated to given the discrepancy for results calculated by techniques used. So, the comparison between analytical and numerical technique shown a good agreement for results calculated, with maximum error did no exceed about (1.46%). There, the results calculated shown the effect for crack depth and position for beam supported with different boundary condition, in addition to, the results shown the effect for load frequency harmonic applied on the beam response. Then, from the results presented can be conclusion that the crack defect lead to decrease the stiffness for beam, then, decreasing for natural frequency and increasing beam deflection response, in addition to, the results shown that the effect for frequency harmonic load applied increase with increase the effect for crack defect.

Volume 11, issue 1, 2020, pp.1-28.

2. Experimental investigation of an active control system for vibration a pipe conveying fluid

Dhurgham Salah Hussein, Muhannad Al-Waily

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

Abstract: Vibration control is achieved by increasing the pressure of the hydraulic damper through a differential pressure gauge that connects to the main pipe, which in turn relates to the electric control valve where the amount of pressure coming out of this valve can be controlled by differential pressure gauge. Thus the hydraulic damper pressure and vibration inside the pipe are controlled. This was done in an actual water pumping station. The operational conditions of that station are taken into account in terms of the pressure generated and the flow rate at different times from the peak demand to the lowest consumption. A damping system is manufactured and connected to reduce vibrations. The normal frequency is measured for several types of fixations, and for the different circumstances in the experimental way. The results are compared with the results calculated by the theoretical method where it is found that the rate of convergence of results is very good and the rate is not exceeding 11.539%. In conclusion, the results have shown that the addition of the hydraulic damper increases the amount of natural frequency of the pipes and thus reduces the amount of response, which leads to a marked increase in the stability of the pipes during the flow. In addition, it is possible to find the imaginary frequency that indicates the stability of the pipes. The results have shown that the imaginary frequency can be reduced (increase stability) by adding a vibration damper to the piping system.

3. Mechanical behavior investigation for hip joint with inclination angle influence by manufacturing and design simulator instrument machine

Muhannad Al-Waily¹, Nibras A. Aziz Al-Roubaiee², Emad Q. Hussein²

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

2 University of Kerbala, Faculty of Engineering, Mechanical Engineering Department, Kerbala, Iraq.

Abstract: The topic of the hip joint has always been of interest to the researchers, which is of a great importance to people who suffer from pain in this joint. This study is focused on the factors that have an effective role in the failure or prolongation of the lifespan of the joint. One of the most important influencing factors is the angle of  inclination of  the implanted cup within the pelvic bone, as it plays a prominent role in reducing or increasing friction, wear, deformation and stresses between the contacted surface that are located between the femoral head and acetabulum cavity. For the purpose of identifying the plastic deformation, strains and stresses resulting from the applying of a static load on the joint, a special device was manufactured for this purpose to simulate the natural movement of the human body, where it was very necessary to find a practical method to simulate the movement of the joint. This simulator instrument is used with the same original biomaterials that produce the hip joint components to make the results as real as possible. The principle of the simulator instrument is based on supplying pressure by a hydraulic system to produce a vertical load on the polyethylene liner and then measuring the produced strains on the liner during specified angles of motion with the three angles of inclination individually. Besides that these results are obtained also by numerical mathematical estimations for comparison and validation. Where, the investigation included study three different values for angle of inclination ( degrees) studied and discussed during three phases of the gait cycle ( degrees). Finally, The experimental and numerical results showed that, when () the convergence strain rates approximately (13.5%) for all values of angle . Also, it is seen the strain values at () are higher than strain values at other angle due to effects of edge loading

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4. Nyquist's theorem in active vibration control system of conservative and non conservative pipes conveying fluid

Dhurgham Salah Hussein, Muhannad Al-Waily

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

Abstract: Fluid conveying pipes are used in all hydraulic systems and enter in all industrial fields, such as water, petroleum products and gases of all kinds. In spite of this widespread and critical importance of fluid conveying pipes, they suffer from major problems. One of these problems is the problem of vibrations that cause the collapse of the systems completely and cause significant economic losses if not avoided. For this reason, the researchers have dealt with this issue in all years, but the problem is not over. This research will highlight the problem of controlling the vibrations resulting from fluid flow inside the pipes, in addition to the study of reducing the vibrations of these pipes. Therefore, after investigation the control and stability for pipe with various methods, with previous papers, presenting in this paper investigation for active control for pipe by using Nyquist’s method. There, the research has studied the response and the natural frequency; the dynamic behavior of conservative and non- conservative pipes conveying fluid using Nyquist's Theorem in the presence with no hydraulic damping (active control); and monitoring the response and stability of each case of stabilization. This study is carried out by deriving differential equations for pipes and for different types of fixation. Where, the analytical solution included drive the general equation of motion for pipe conveying fluid and then solving its equation by using Galerkin’s technique, and then, calculating the stability by using Nyquist’s techniques.

5. Root locus theory in active vibration control system of pipes conveying fluid rested on different supports

Dhurgham Salah Hussein, Muhannad Al-Waily

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

Abstract: In spite of this widespread and critical importance of fluid conveying pipes, they suffer from major problems. One of these problems is the problem of vibrations that cause the collapse of the systems completely and cause significant economic losses if not avoided. Where, fluid conveying pipes are used in all hydraulic systems and enter in all industrial fields, such as water, petroleum products and gases of all kinds. For this reason, the researchers have dealt with this issue in all years, but the problem is not over. This research will highlight the problem of controlling the vibrations resulting from fluid flow inside the pipes, in addition to the study of reducing the vibrations of these pipes. This study is carried out by deriving differential equations for pipes and for different types of fixation. The research has studied the response and the natural frequency; the dynamic behavior of different types of stabilization of the pipes in the presence with no hydraulic damping (active control); and monitoring the response and stability of each case of stabilization. Where, in this paper using root locus technique to calculate the control for pipe conveying fluid. Thus, the investigation included calculated the effect for different damper parameters and fluid on the pipe stability. There, this work is expansion for previous study investigated the control for pipe vibration with using other stability and control theories, and comparison for presenting results with previous results, therefore, form comparison results found that the loot locus technique is a good technique can be using to investigation the stability and control for pipe fluid.