Dissertation Defense - Isam Jabbar Ibrahim Bajilane (PHDME)

Isam Jabbar Ibrahim Bajilane - Ph.D. Mechanical Engineering

Assoc.Prof. Güney Güven Yapıcı - Advisor

DEVELOPMENT OF A SOLID STATE SPOT WELDING TECHNIQUE FOR THE MANUFACTURING OF DEFECT FREE JOINTS

Date: 12.06.2019

Time: 14:00

Location: AB2 G12

Thesis Committee: 

Assoc. Prof. Güney Güven Yapıcı,  Özyeğin University

Asst. Prof. Altuğ Melik Başol,  Özyeğin University

Asst. Prof. Yasemin Şengül Tezel,  Sabancı University

Asst. Prof. Polat Şendur,  Özyeğin University

Asst. Prof. Mehmet İpekoğlu,  Turkish German University

Abstract

Intermediate layer friction stir spot welding (IL-FSSW) was a novel welding process developed for welding similar and dissimilar metallic sheets. This new approach is considered as a development of the conventional friction stir spot welding (FSSW) to avoid the keyhole problem appearance. The process is carried out at different welding parameters and using a pinless welding tool in addition to a 6 mm diameter of 1 mm thick the intermediate layer (IL) inserted between the sheets in the welding area. Taguchi technique is used to evaluate the influence of the process parameters depending on the design of experiment (DOE) method. The experimental results reveal that the IL-FSSW process is suitable to produce perfect joints have a superior appearance with high strength and hardness. The microstructure of the welded cross-section area showed that the IL-FSSW joints have extended hooks formed in the vicinity of the welding tool diameter. Shear-tensile and Fatigue tests were conducted on welded samples. The scanning electron micrographs of the failure samples in both the tensile and fatigue tests were examined to study the fracture modes and crack propagation. The plug and nugget pull-out failure modes were seen in the fractured surfaces. A numerical investigation was performed to model the temperature distribution and welds strength during weld processing. The results of the models were compared with the experimental values measured to validate the results. The simulations showed limited levels of error arranged between 2.2% to 21% when compared with experiments result.

Bio

Isam Jabbar Ibrahim was born in 1983 in Baghdad, Iraq. After getting a technical diploma in Mechanics Techniques/Production from the Institute of Technology-Baghdad in 2002, he enrolled on a Bachelor’s and Master’s program at the Middle Technical University. He received his Bachelor’s in Engineering in Welding Techniques in 2005. He finished his Master’s in Welding Engineering Technology in 2009. Then, he worked at the same university as a lecturer in the Welding Engineering Department for four years. In 2013, he received a scholarship from the Iraqi Government to complete his doctoral studies in the Republic of Turkey. Currently, he is pursuing a Ph.D. degree in Mechanical Engineering at Ozyegin University under the supervision of Associate Professor Dr. Guney Guven Yapici in MEMFIS research group. His research interest is mainly concentrated on developing a novel friction stir welding process called Intermediate Layer Friction Stir Spot Welding (IL-FSSW).