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Dr. Gerges Edwar Mehanny Beshay :: Theses : |
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| Title | Structural Dynamic Optimization of Wind Turbine Blades Using Material Grading Concept |
| Type | PhD |
| Supervisors | T Kalifa; Karam Maalawy; S Abdrabo |
| Year | 2016 |
| Abstract | This thesis is a research in material/design optimization of horizontal axis wind turbine blades. The major aim of the present optimization process is to improve the dynamic performance of the blade spar that represents the main element supporting both static and dynamic loads applied on the wind turbine blade. The blade spar is modeled as a cantilevered thin-walled composite beam constructed from multiple segments each of which has different material composition, cross sectional dimensions, and length. A structural dynamic model using transfer matrix method is developed and the associated eigenvalue problems of the blade spar are solved. Flapwise, edgewise, extension, twist, and coupled vibration modes are considered for both CUS and CAS layup configurations. Results extracted from the developed dynamic model are compared to other researches results. Finite element modeling of the blade spar is performed using NX Nastran solver in order to validate the developed analytical modeling results. Lanczos method is used to provide the natural frequencies and normal mode shapes of the blade spar. Experimental investigations are also performed in order to validate the analytical results. Physical and mechanical tests are carried out in order to define material properties. Experimental modal analysis is performed on a number of thin walled composite beams with different configurations. The analytical, FEM, and experimental results showed good agreement to each other. A case study including the optimization of a medium scale composite blade for a 750 kW wind turbine is presented. Full description of the wind turbine configurations and loading conditions are discussed. A parametric study is carried out in order to emphasize the effect of changing the selected design variables on mass and natural frequencies of the considered blade spar. Computer programs using basic and MATLAB programming tools have been developed and implemented in order to perform the parametric study. The results have shown that the approach implemented in the present investigation is reasonably efficient in attaining improved designs of the blade spar in a reasonable time. The results of the developed optimization models have shown significant improvements in the desired design objective relative to a baseline design. |
| Keywords | |
| University | Benha University |
| Country | Egypt |
| Full Paper | download paper |
| Title | MECHANICAL AND TRIBOLOGICAL CHARACTERISTICS OF EPOXY-BASED POLYMERIC MATRIX COMPOSITES REINFORCED WITH VARIOUS CERAMIC PARTICULATES |
| Type | PhD |
| Supervisors | T Kalifa; T S Mahmoud; M Abdel-Aziz |
| Year | 2010 |
| Abstract | Polymeric matrix composites (PMCs) are advanced engineering materials that are widely used in place of conventional materials such as metals in the manufacturing of automobile and aerospace industries due to its high strength to weight ratio and resistance to wear. The aim of the present work is to study the mechanical and the tribological characteristics of epoxy-based polymeric matrix composites. The polymeric matrix used in this investigation is a commercial epoxy resin manufactured by Chemicals for Modern Buildings Company, CMB, Egypt, is known as (KEMAPOXY 150). The epoxy matrix was reinforced with different micro-sized ceramic particles of alumina (Al2O3), silicon carbide (SiC), and graphite with different volume fractions. The PMCs were prepared by using the mechanical stirring method. The particulates having average size of 15 µm were added to the epoxy matrix by 10, 20, and 30% by volume. A number of nine composites were produced as well as the pure matrix. Density, microstructure, hardness, compressive strength, as well as the tribological characteristic were studied. Wear tests were conducted at both dry and water lubricated sliding conditions using a pin-on-ring wear tester. Wear rate as well as the coefficient of friction were measured. Scanning electron microscope (SEM) was used to study the worn surfaces of the PMCs after wear tests. The results showed that composites of epoxy/SiC, epoxy/Al2O3, and epoxy/graphite have higher densities than that of the pure epoxy matrix. Such increase in density was found to be proportional to the particle content in the composite. Epoxy/SiC and epoxy/ Al2O3 composites exhibited a higher compressive strength and hardness than that of the base matrix. Epoxy/ Al2O3 composites exhibited the highest wear resistance. |
| Keywords | |
| University | Benha University |
| Country | Egypt |
| Full Paper | download paper |
| Title | MECHANICAL AND TRIBOLOGICAL CHARACTERISTICS OF EPOXY-BASED POLYMERIC MATRIX COMPOSITES REINFORCED WITH VARIOUS CERAMIC PARTICULATES |
| Type | PhD |
| Supervisors | T Kalifa; T S Mahmoud; M Abdel-Aziz |
| Year | 2010 |
| Abstract | Polymeric matrix composites (PMCs) are advanced engineering materials that are widely used in place of conventional materials such as metals in the manufacturing of automobile and aerospace industries due to its high strength to weight ratio and resistance to wear. The aim of the present work is to study the mechanical and the tribological characteristics of epoxy-based polymeric matrix composites. The polymeric matrix used in this investigation is a commercial epoxy resin manufactured by Chemicals for Modern Buildings Company, CMB, Egypt, is known as (KEMAPOXY 150). The epoxy matrix was reinforced with different micro-sized ceramic particles of alumina (Al2O3), silicon carbide (SiC), and graphite with different volume fractions. The PMCs were prepared by using the mechanical stirring method. The particulates having average size of 15 µm were added to the epoxy matrix by 10, 20, and 30% by volume. A number of nine composites were produced as well as the pure matrix. Density, microstructure, hardness, compressive strength, as well as the tribological characteristic were studied. Wear tests were conducted at both dry and water lubricated sliding conditions using a pin-on-ring wear tester. Wear rate as well as the coefficient of friction were measured. Scanning electron microscope (SEM) was used to study the worn surfaces of the PMCs after wear tests. The results showed that composites of epoxy/SiC, epoxy/Al2O3, and epoxy/graphite have higher densities than that of the pure epoxy matrix. Such increase in density was found to be proportional to the particle content in the composite. Epoxy/SiC and epoxy/ Al2O3 composites exhibited a higher compressive strength and hardness than that of the base matrix. Epoxy/ Al2O3 composites exhibited the highest wear resistance. |
| Keywords | |
| University | Benha University |
| Country | Egypt |
| Full Paper | download paper |
