Tesfaye, Tamrat (phD)Dinbassa, Samson2018-07-062023-11-182018-07-062023-11-182007-11http://etd.aau.edu.et/handle/12345678/7037The welding process has been used extensively in the fabrication of many structures including ships, airplanes, buildings, bridges, vehicle bodies, pressure vessels, etc. It provides many advantages over other joining techniques. To mention only a few, it provides better mechanical properties, air and water tightness and good joining efficiency. However, there are various problems such as residual stresses and shape distortion associated with the construction of welded structures. When a material is being welded, it experiences local heat due to the welding heat source. The temperature field inside the weldment is not uniform and changes as the welding progresses. The welding heat cycle gives rise to a complex strain field in the weld metal and in the base metal regions near the weld. These strains, along with the plastic upsetting, create the residual stresses that remain after the welding is completed. In addition, shrinkage and distortion are also produced. Residual stresses and distortion are highly undesirable in welding technology. Thermal stresses during welding often cause cracking. Some of the above weld related problems can be solved by adhering to a preset weld design practice and employing appropriate weld process procedure in the welding tasks. In our country, Ethiopia, there are limited numbers of heavy duty vehicles body builders. Those body builders extensively use welding. In those local body builders there is lack of proper weld design practice in the fabrication of heavy duty vehicle bodies. Moreover, there is no well developed/structured welding process procedure they have adapted except in the cases of internationally undertaken projects. This fact enhances the weld related problem mentioned above on the vehicle bodies fabricated locally. In this paper case study is made on four local representative vehicle body builders focusing on their weld design and WELD DESIGN OF HEAVY DUTY VEHICLE BODIES 11 processes. From the case studies the general problems related to the weld design and process of the local heavy duty vehicle body builders is identified. Eventually, general recommendation is made on weld design and process of heavy duty vehicle bodies that the Ethiopian heavy duty vehicle body builders are to adapt or practice.enMechanical EngineeringThesis