Browsing by Author "Hailemariam, Nigus (Mr.) Co-Advisor"

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    Weight Optimization of Front Coil Spring Suspension Using Composite Material for Bajaj by FEM
    (AAU, 2018-06) Medhanye, Berhane; Tamrat, Tesfaye (PhD); Hailemariam, Nigus (Mr.) Co-Advisor
    The main objective of this research is to minimize the weight of the helical coil spring of Bajaj without reducing the strain energy and keeping good the stiffness of the spring. This is done by comparing the existing conventional steel spring with composite materials. Two composite materials (Carbon/Epoxy and Carbon/Carbon Nanotube/Epoxy) are selected by their advanced mechanical, and physical properties. Properties of each composite components are taken from previously experimental and analytical done literature reviews. Using rule of mixtures and HalpinTsai equations for unidirectional ply, mechanical properties of both composite are determined. From literature reviews composite mixture has good properties for 60% of fiber. So the volume fraction of carbon fiber for Carbon/Epoxy is 60%, and for the hybrid composite Carbon/CNT/Epoxy the volume fraction is 1% Carbon Nanotube fiber is added, 59% carbon fiber and the remaining 40% is Matrix (Epoxy Risen). Three dimensional helical coil spring is modeled using CATIA V5R19 and analyzed using ANSYS Workbench17.2.to compare the parameters (Shear stress, Fatigue life, Strain Energy and Deformation) of existing steel spring with Carbon/Epoxy and Carbon/ Carbon Nanotube /Epoxy composites. As a result for the same dimension of coil spring, the weight of Carbon/ Carbon Nanotube /Epoxy, Carbon/Epoxy coil spring is 81% and 80.5% lighter than steel coil spring. But the deflection of both composite coil springs is increased, so to increase the deflection of composite coil spring the dimension of the coil spring is modified. For the modified coil spring, Shear stress is reduced, Strain energy is still better than the steel one. And the result shows Carbon/Carbon Nanotube/Epoxy composite better satisfies the objective of the research than the steel and Carbon/Epoxy composite. Therefore, Carbon/ Carbon Nanotube /Epoxy composite is selected as coil spring material.
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    Weight Optimization of Single Speed Electric Vehicle Transmission Housing
    (Addis Ababa University, 2020-07) Bethelhem, Tamiru; Daniel, Tilahun (PhD); Hailemariam, Nigus (Mr.) Co-Advisor
    An electric vehicle is a vehicle powered by an electric motor, instead of an internal combustion engine, and the motor run using the power stored in the batteries. Electric Vehicles are known as zero emissions vehicles and are much environment friendly than gasoline powered vehicles. Even though electric vehicle brings an eco-friendly, green solution to the automotive industry sector, there exist drawbacks when compared to conventional gasoline-powered cars. The main drawback is that electric vehicles on average travel a shorter range than gasoline powered vehicles due to the heavy weight, and this puts pressure on the battery pack which forced to drain out faster. To optimize the energy consumption of electric vehicles the reduction of transmission housing weight is important. The main objective of this research work is to develop an optimized composite version of an existing aluminum transmission housing for single speed electric vehicle. The selected composite material characterized using AUTODESK HELIUS COMPOSITE and the free-size optimizations executed using one of the finite element analysis software ANSYS OptiSlang. The optimized T1000-3501-6Epoxy with T800-3501-6Epoxy laminate checked for the static and modal deformation. From the ANSYS Optislang optimization the weight of the transmission housing reduced by 22%, where the weight of Aluminum 6061-T6 was 5.4kg and the optimized weight by using composite + Aluminum material was about 4.19kg which satisfies the constraint conditions.