School of Mechanical and Industrial Engineering

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http://etd.aau.edu.et/handle/12345678/140

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Browsing School of Mechanical and Industrial Engineering by Author "Abdi, Zewdu (PhD)"

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    Design and Analysis of Pick Up and Transfere Windrow Forage to Trailer Device
    (Addis Ababa University, 2014-01) Girma, Lemmi; Abdi, Zewdu (PhD)
    This thesis present the design and analysis of pick up windrow forage and transfer to trailer device. A windrow forage is a narrow strip of forage that dries at a slower rate but does not require further manipulation before harvest. Most of harvesting technologies are complex in structure and expensive in cost. This paper will be solving the problem of complexity and expensive cost of existing technology. Main parts of machine component are selected by preparing concept selection based on created selection criteria. Pick up component are designed the way it can be self-adjusted for non uniform flat land surface (pick - valleys height up to 18 cm) by means of spring load. Picked up forage by pick up finger transferred to inclined feed dosing and then conveyed to trailer by means of pushing rod finger attach to flat belt conveyor. Power is transferred from tire to pick up component and conveyor by using flat belt. Design and design result of each part are included in this paper and material selection for most part based on the availability in Ethiopia. Some part of machine such as tire, bearing, bearing house (block), and spring belt are selected based on available standard catalog. 3D and 2D of different assembled and detail component are generated by catia that is power full and modern modeling soft ware and numerical solution also done by it which is finite element analysis package. Key words: Concept Selection, Design, Analysis, 3D and 2D Model by Catia.
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    Design and Development of teff seed broadcaster
    (2012) Shukurea, Abdulhakim; Abdi, Zewdu (PhD)
    An analysis of the motion of teff seed particle on a rotating cone shaped disc is conducted and also basic equations of motion derive for a single teff seed particle. The analysis directly applied to the flow of teff seed particle on a spinning disc spreader. Equations of motion are developed for cone shaped disc and pitched type vane spreader. The derived equation of motion form parts of the basis of MATLAB-SIMULINK model simulation for spinning disc spreader with equation of motion through the air (off-disc) model. In MATLAB-SIMULINK simulation, the motion of single teff seed particle is considering with different initial conditions (physical properties of teff seed such as moisture content) and also varying different machine parameters (such as cone angle, pitch angle and rotational speed of disc). Different machine parts were designed and the mass flow rate of teff seed was calculated. Seed hopper was also designed. Shafts were designed and selecting of material for shaft was done, and checked. Bevel gear was designed and the principal dimension was found. Four bearings were selected and checked for stability under the existing loads.
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    Design and Modification of Appropriate Reel Mechanism to Harvest Tef Crop
    (2012-10) Zeleke, Ephrem; Abdi, Zewdu (PhD)
    he relationships between the deflection angle and deflection force acting on a bunch of crop stalk in the gathering operations of a combine harvester reel were analyzed. Mechanical crop model based on bending theory with regard to an elastic beam were applied in this analysis. In the model, the effect of flexural rigidity, crop ear weight and reel force on tef crop stalk in the angle of deflection. A model of crop stem deflection by the combine harvester reel is formulated. The equations derived thereof are evaluated on the basis of empirical data that were acquired through deflection of crop stems in a ready for harvest tef crop in the field. Applications of crop stem deflection to reel design and operation are used for determination of the number of reel tine bar and angular displacement of successive tine bar. The reel design includes determination of the number of tine bar, angular displacement of the reel and rotational speed of reel. The reel adjustment forward and backward relative to the cutter bar and also height adjustment appropriate to the tef crop height. The design of chain derives, shaft and bearing took varies data with appropriated values from the actual combine harvester such as reel speed and maximum torque. In chain drive design, the diameter of larger sprocket and the length of chain were calculated. In shaft design, determination of diameter of shaft that holds the reel force and sprocket tangential force by selected material. In bearing selection, calculating basic dynamic load rating was made to determine type of bearing number, then the correct bearing selected.
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    Design and Optimization of Electric Motor Driven Mechanical Oil Press
    (Addis Ababa University, 2013-11) Mekonnen, Addisalem; Abdi, Zewdu (PhD)
    There are different types of oil press machine developed previously which are used to squeeze oil from different types of an oil seed. In this Research work one type of oil press, manually operated oil press, is improved into electric motor driven mechanical oil press with rack and pinion gear system as a main mechanical part of the machine. This improvement is used to solve the cost problem, reduce work time, and streamline the existing machine to be more efficient and productive. The main procedures to comply this improvement are design of parts of the machine to get optimized dimensions of the parts and setting the controlling mechanism. In this procedure main parts of the machine are designed to find their dimensions and to select appropriate material and also its stress analysis is performed using finite element analysis software to find stress concentration area and its maximum stress value and then to compare with values obtained in the design analysis. The other part and power source of the machine is an electric motor, in this thesis it is also dealt with selection of motor type including its specification for safe and appropriate operation. The controlling mechanism of the motor using microcontroller for automatic operation of the motor is selected and assembly language has been written since the motor is bi-directional or it rotates clockwise and anti-clockwise, which is used to move the ram up and down. After completing the design obtained results and selected materials are safe to squeeze edible oil.
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    Design of Variable Speed Vibrating Plate Soil Compactor
    (Addis Ababa University, 2015-05) Tilahun, Anteneh; Abdi, Zewdu (PhD)
    When soil is dug up or moved, it becomes aerated and loses some of its density. It must be compacted or allowed to settle before a structure (house, buildings, roads etc.) is built on top of it. Potholes in roads, sinkholes in parking lots, and severe cracking or settling in foundations are very often the result of a poorly compacted base. Now a day’s different compactor machine are used to compact different soil texture. Each compaction machines are designed to compact for specific type of soil. The motive of this research is to design variable speed vibrating plate soil compactor that can bring uniform compactness and can increase the load bearing capacity of different soil texture. This thesis research focuses on design of variable speed vibrating plate compactor, which has the property and characteristics of four deferent compactor machines such as sheep’s foot roller, smooth wheel roller, rammer and vibrating plate compactor. Therefore it will avoid selecting of different compaction machine for different soil texture to bring uniform soil compactness. If this design finally be manufactured, it will work for any kind of soil texture and save space, time, and cost to bring uniform soil compactness even if soil texture is different from distance to distance. In this thesis research there are best solutions principles based on weighted objective method for different components of the variable speed vibrating plate compactor and choose different best option by computing based on different criteria. This thesis research has addressed detail design of different components of variable speed vibrating plate compactor such as design of Rotating shaft, Hydraulically controlled variable eccentricity Eccentric Rotating Mass, gear, Pulley, Belt, springs, Vibration Isolator (Damper) and Hydraulically controlled variable surface Vibrating Plate, selection bearings, pump and prime mover And also indicted the vibration analysis and vibration response of the machine to soil damping and spring constants. Variable speed vibrating plate compactor has the ability of maximum efficiency to compact 100m2 areas within 600second on single trip which is within acceptable range of compaction time when it compared with exiting compaction machine.. The estimated total market cost is 223,314 birr which is relatively low-priced since it replaces four different compactor machines.
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    Developing Manually Driven Street Cleaning Machine (Scm)
    (Addis Ababa University, 2013-12) Teklemariam, Aklilu; Abdi, Zewdu (PhD)
    In this research project, a mechanism was developed to remove dirt from surface of street and sidewalks. Before concept generation and selection, characteristics, types and distribution of debris on street surface was analysed to facilitate the next design phase. During conceptual design phase, different concepts were proposed using concept generation methods and the best concepts were selected. From the selected concepts, the design was developed in accordance with technical and economic criteria and general arrangement, component shapes and materials were determined. Moreover, the components and assembly were analysed and tested using SolidWorks motion analysis tools and SolidWorks simulation tool. The machine is compact and manually driven, and capable of reducing the cost of road surface cleaning work. It also prevents dust from being blown up without spraying water on the road surface during the cleaning process. At optimum working speed, it absorbs dirt efficiently without damaging the road surface. Moreover, it applies an absorbing force to the debris effectively. In its working process, the coarse debris cleaning mechanism will clean larger litters first, and then the spur gear mechanism drives the roller brush rotating at optimum speed, and thus produces negative pressure to direct the fine debris into the container. By pushing the machine, it moves the coarse and fine debris towards the dirt container. Therefore, it saves power and reduces labor force more than manually cleaning using brooms, and reduces cost when compared to employing street sweepers.