Mechanical properties of ti6al4v parts produced by electron beam melting and topology optimization in different building directions

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Makina Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2018

Öğrenci: SELEN TEMEL YİĞİTBAŞI

Danışman: ERHAN İLHAN KONUKSEVEN

Özet:

Titanium and its alloys are used in various industries due to their mechanical properties such as high corrosion resistance, high strength and low-density. However, utilization of parts made of titanium are limited since the lead time for raw material is long, they are hard to machine, and the machining costs are high. On the other hand, it is possible to produce complex parts with powder material by additive manufacturing techniques, and there is a growing interest in research on these new technologies. Electron Beam Melting, one of the additive manufacturing methods, gives chance to designers to develop complex parts that have comparable mechanical properties to the parts produced by conventional methods. In the first part of this study, nine samples according to ASTM E8 standard were produced in different building directions (according to machine coordinate system X, Y and Z). To see surface imperfections effect on mechanical properties, one of the samples built in each direction were machined by lathe. After that, tensile test was performed, surface roughness was measured for each specimen and the fracture surfaces were examined. As a result, it was observed that the parts built in vertical direction have better tensile properties. In the second part of the thesis, to show that it is possible to produce light weight complex parts that satisfy the system function by additive manufacturing, topology optimization of an aircraft fitting was done with data from the experimental part. Two optimizations were performed for the parts to be manufactured in vertical and horizontal building directions. Location of the parts were determined according to the load cases and corresponding stress values. After optimization, newer designs with around 40% less weight were obtained without sacrificing the system performance requirement.