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Item type:Publication, Access status: without files , Finite Element Analysis of Dynamic Behavior of NREL 5-MW Horizontal Axis Wind Turbine Blade(IEEE, 2023-10-25); ; ; ; Khazem, Enas A.This research offers an advanced numerical simulation utilizing the finite element technique to study in detail the dynamic behavior of horizontal axis wind turbine (HAWT) blades. The 3D Finite Element model developed is intended to comprehensively examine the interactions among different operating conditions, such as material type and thickness, that impact the natural frequencies and mode shapes of the NREL offshore wind turbine blade (5 MW). This investigation involved an intensive examination of four distinct blade thickness values (20 mm, 30 mm, 40 mm and 50 mm), in conjunction with an assessment of how each material (Composite, Titanium Alloy, Aluminium 2024 and Aluminium alloy) affects dynamic response. Notably, the study revealed that blade thickness emerged as a prominent factor affecting wind blade dynamics, with natural frequency increases of over 15% observed as blade thickness varied. These findings provide crucial insight into the complex behavior of wind turbine blades and can pave the way towards optimized designs and improved performances of wind energy systems.Publicationtype: Conference Paper17 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Frictional material selection of dry clutch disc based on the weighted factor and finite element methodsThe main task of the frictional facing of a clutch disc is to transfer the power from the driving to the driven parts. High frictional heat will be generated when the frictional facing comes into contact with the moving surfaces (flywheel and pressure plate). In this research paper, the selection of the frictional-facing material of the clutch disc has been investigated to obtain the optimal thermal behavior of the clutch system. It used five different frictional materials (St37-2, HCC, G95, LUK, and Tiger), and then applied the Weighted Factor Method to find the optimal frictional material that can be used in the clutch disc. In the second part, an axisymmetric finite element (FE) model has been developed to simulate the working of the clutch system during the heating phase. A comparison was made between the results of the thermal problem using the FE method and the Weighted Factor Method, where a high agreement was obtained between them to determine the optimal frictional material for the clutch disc. It was found that the frictional material (HCC) is the superior one with the highest performance index equal to 90.7 and the lowest values of the maximum temperature (353.7 K). In contrast, the frictional material (St37-2) is the poorest one, with the lowest performance index equal to 30.7 and the highest values of the maximum temperature (378.2 K).Publicationtype: Journal Article58 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , A systematic approach to stable grasping of a two-finger robotic hand activated by jamming of granular media(Multidisciplinary Digital Publishing Institute (MDPI), 2023-04-18); ; ; ; A systematic approach is presented to achieve the stable grasping of objects through a two-finger robotic hand, in which each finger cavity was filled with granular media. The compaction of the latter, controlled by vacuum pressure, was used to adjust the structural and contact stiffness of the finger. The grasping stability was studied under the concurrent effect of an external torque and applied vacuum pressure. Stable grasping was defined as the no slippage condition between the grasped object and the two fingers. Three control schemes were adopted and applied experimentally to ensure the effectiveness of the grasping process. The results showed that stable and unstable grasping regions exist for each combination of applied torque and vacuum pressure. The two-finger robotic hands can be further improved for applications that require high load-carrying capabilities.Publicationtype: Journal ArticleScopus© Citations 2 43 255 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Analysis of modified finite length journal bearing under position perturbation(Multidisciplinary Digital Publishing Institute (MDPI), 2023-04-11); ; ; ; The performance of journal bearings is significantly affected by the presence of misalignment, which is usually an accompanying problem for this type of bearing. This includes exceeding the design limits for the maximum pressure and the minimum film thickness levels, which affect, in other words, the load-carrying capacity of the system. In addition, it raises the possibility of increasing the wear rate at the bearing edges and increases the friction coefficient at high levels of misalignment. This paper deals with the problem of finite-length misaligned journal bearings, considering a novel comparison between two cases of misalignments: the general 3D misalignment and the vertical misalignment problems for modified bearings. The effect of introducing a variable axial bearing profile on the bearing characteristics and the time responses of the rotor bearing system under position perturbation has also been investigated. The numerical solution of this hydrodynamic problem is based on the finite difference method using Reynolds boundary conditions method. Results show that using a variable bearing profile improves bearing characteristics, such as increasing the minimum film thickness significantly and reducing the pressure levels in addition to reducing the friction coefficient. Furthermore, the modification enhances the rotor-bearing stability under position perturbation, extending the speed range for a safe operation.Publicationtype: Journal Article49 83 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Optimization of small horizontal axis wind turbines based on aerodynamic, steady-state, and dynamic analyses(Multidisciplinary Digital Publishing Institute (MDPI), 2023-02-24); ; ; ; In this article, the model of a 5 kW small wind turbine blade is developed and improved. Emphasis has been placed on improving the blade’s efficiency and aerodynamics and selecting the most optimal material for the wind blade. The QBlade software was used to enhance the chord and twist. Also, a new finite element model was developed using the ANSYS software to analyze the structure and modal problems of the wind blade. The results presented the wind blade’s von Mises stresses and deformations using three different materials (Carbon/epoxy, E-Glass/epoxy, and braided composite). The modal analysis results presented the natural frequencies and mode shapes for each material. It was found, based on the results, that the maximum deflections of E-glass, braided composite and carbon fiber were 46.46 mm, 33.54 mm, and 18.29 mm, respectively.Publicationtype: Journal ArticleScopus© Citations 3 85 396 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Effect of chamfer form and parameters on the characteristics of finite length journal bearing under impact load(Multidisciplinary Digital Publishing Institute (MDPI), 2023-02-10); ; ; ; Journal bearings in typical applications are subjected to misalignment due to several causes, such as shaft deformation under load and errors related to the installation and manufacturing processes. Misalignment has well-known severe negative consequences on the performance of the bearings. This paper deals with the bearing chamfer to reduce these consequences of misalignment, and two forms of bearing edge modification are considered in the analysis. These forms are linear and curved chamfering of the bearing edges, where the height of the chamfer in the circumferential direction and the length of the modification in the longitudinal direction are considered as geometrical design parameters. The investigation includes a numerical solution of the hydrodynamic lubrication problem of finite length journal bearing, considering 3D misalignment cases using the finite difference method. This includes the assessment of the chamfer forms and their effects on the bearing performance in terms of the main bearing design parameters. Furthermore, the stability of the chamfered bearings is also investigated under impact load. Results showed that both chamfer forms are beneficial for a certain limit of the design parameters in reducing the maximum pressure and coefficient of friction and in elevating the film thickness levels, extending the range of misalignment in which the journal bearing can operate safely. In addition, the chamfered bearings in both forms showed more stability range in terms of the critical speed and shaft center trajectories under impact load. The bearings with the curved chamfer, where the slope is continuous at the start of modification, showed more uniform film thickness levels, and their shaft center trajectories were closer to the perfectly aligned bearing in the stable operating range of the system.Publicationtype: Journal ArticleScopus© Citations 4 77 119 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Microstructural and mechanical characterization of ledeburitic AISI D2 cold-work tool steel in semisolid zones via direct partial remelting process(Multidisciplinary Digital Publishing Institute (MDPI), 2023-02); ; ; ; The success of the thixoforming process largely depends on the created microstructure, which must be globular in the liquid phase. The solid–liquid structural changes that occur on as-annealed D2 tool steel when it is subjected to the so-called DPRM are described in this work (direct partial remelting method). The paper discusses phase changes and how carbide dissolution affects grain boundary liquation and grain spheroidization. Equiaxed grains with undissolved carbide particles have been found in the microstructural analysis at 1250 °C; however, the carbides gradually disappear as the temperature rises. Additionally, the equiaxed grains were transformed to a globular structure, which improves the shape factor and grain size for the thixoforming process. For AISI D2 thixoforming, which produced grains with a diameter of 50 μm and a shape factor of 1.18, temperatures of 1300 °C and a holding period of 5 min were the optimum parameters. The outcomes also showed that the mechanical properties of the AISI D2 were greatly enhanced after using direct partial remelting, where hardness was increased from 220 Hv to 350 Hv and tensile strength from 791 MPa to 961 MPa.Publicationtype: Journal ArticleScopus© Citations 1 48 99 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Analysis of the performance of chamfered finite-length journal bearings under dynamic loads(Multidisciplinary Digital Publishing Institute (MDPI), 2023-01-22); ; ; ; Misalignment is one of the most common challenges that the normal operation of journal bearings faces. This type of problem may be the result of a wide range of reasons, such as bearing wear, shaft deformation, and errors related to the manufacturing and installation process. The main undesirable consequences of the misalignment, such as pressure rise and lubricant film reduction, are concentrated on the bearing edges. Therefore, chamfering the bearing edges reduces such misalignment-related drawbacks. This work presents a novel numerical solution to the problem of finite-length journal bearing considering edge chamfering. This solution involves the determination of the levels of lubricant layer thickness and pressure distribution in addition to the journal trajectory under impact load with the related stability limits. The finite difference method is used in this solution, and the equations of motion are also solved numerically using the Runge–Kutta method. The Results of this novel analysis show that chamfering the bearing edges increases the film thickness and reduces pressure spikes associated with the system operation under the case of 3D misalignment. Furthermore, the chamfered bearing shows a wide stability range under impact loads, where the normal bearing is unstable as the critical speed increases by 26.98%, which has positive consequences on the journal’s trajectory.Publicationtype: Journal ArticleScopus© Citations 5 42 96 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Intelligent robotic welding based on a computer vision technology approach(Multidisciplinary Digital Publishing Institute (MDPI), 2022-10-29); ; ; ; Robots have become an essential part of modern industries in welding departments to increase the accuracy and rate of production. The intelligent detection of welding line edges to start the weld in a proper position is very important. This work introduces a new approach using image processing to detect welding lines by tracking the edges of plates according to the required speed by three degrees of a freedom robotic arm. The two different algorithms achieved in the developed approach are the edge detection and top-hat transformation. An adaptive neuro-fuzzy inference system ANFIS was used to choose the best forward and inverse kinematics of the robot. MIG welding at the end-effector was applied as a tool in this system, and the weld was completed according to the required working conditions and performance. The parts of the system work with compatible and consistent performances, with acceptable accuracy for tracking the line of the welding path.Publicationtype: Journal ArticleScopus© Citations 4 81 657 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Development of hybrid intelligent models for prediction machining performance measure in end milling of Ti6Al4V alloy with PVD coated tool under dry cutting conditions(Multidisciplinary Digital Publishing Institute (MDPI), 2022-09-25); ; ; ; Ti6Al4V alloy is widely used in aerospace and medical applications. It is classified as a difficult to machine material due to its low thermal conductivity and high chemical reactivity. In this study, hybrid intelligent models have been developed to predict surface roughness when end milling Ti6Al4V alloy with a Physical Vapor Deposition PVD coated tool under dry cutting conditions. Back propagation neural network (BPNN) has been hybridized with two heuristic optimization techniques, namely: gravitational search algorithm (GSA) and genetic algorithm (GA). Taguchi method was used with an L27 orthogonal array to generate 27 experiment runs. Design expert software was used to do analysis of variances (ANOVA). The experimental data were divided randomly into three subsets for training, validation, and testing the developed hybrid intelligent model. ANOVA results revealed that feed rate is highly affected by the surface roughness followed by the depth of cut. One-way ANOVA, including a Post-Hoc test, was used to evaluate the performance of three developed models. The hybrid model of Artificial Neural Network-Gravitational Search Algorithm (ANN-GSA) has outperformed Artificial Neural Network (ANN) and Artificial Neural Network-Genetic Algorithm (ANN-GA) models. ANN-GSA achieved minimum testing mean square error of 7.41 × 10−13 and a maximum R-value of 1. Further, its convergence speed was faster than ANN-GA. GSA proved its ability to improve the performance of BPNN, which suffers from local minima problems.Publicationtype: Journal ArticleScopus© Citations 5 44 333