Akademik Veri Yönetim Sistemi
Tezin Türü: Yüksek Lisans
Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Makina Mühendisliği Bölümü, Türkiye
Tezin Onay Tarihi: 2012
Öğrenci: BORA GERÇEKER
Danışman: ABDULLAH ULAŞ
Özet:Unintentional drop of munitions could be encountered during the storage, transportation, and loading processes. In such an impact, malfunctioning of crucial components of munitions is the worst scenario that may be encountered and level of loads should not reach to critical levels. From two possible methods, experimental one is not frequently applied owing to high cost of money and time. On the contrary, particularly in last couple of years, interest is shifted to numerical simulations such as finite element method. In this thesis, foam materials will be investigated as energy absorbers to reduce the effect of loads during the impact. However, modeling the behavior of foam materials by FE codes is a challenging task. In other words, more than a few material parameters which are not commonly specified in literature are sufficient to represent the behavior of foams in an appropriate way. For this reason, material characteristics of the selected two foam materials, expanded polypropylene and v polyethylene, have been obtained in this study. Characterization of EPP and PE is followed by the selection of the appropriate material models in LS-DYNA which is a nonlinear explicit finite element code. Drop tests of munitions on which initially specified foam materials are integrated were done to identify the load levels. Validation of drop tests which are explained in detail in this thesis has been accomplished by LS-DYNA. Final section of the thesis is related to optimization of the foam geometry which will provide reducing load levels to allowable limits. After optimization studies, three alternative geometries which succeed in to reduce loads to allowable load levels were reached. Finally, one of three alternatives is selected considering cost and manufacturing difficulties.