Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Enhancement of Ballistic Properties by Hybridization Method of Multi-Layered Composite Panels(01. Izmir Institute of Technology, 2020) Üstün, Hikmet Sinan; Tanoğlu, Metin; Tanoğlu, Metin; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyHigh performance fiber reinforced composite structures are used for ballistic applications in recent years due to several advantages lightweight, high strength and high energy absorbing capability. In this regard, it is aimed to enhance ballistic performance of fiber reinforced composites by hybridization method in this thesis. Two of most used fiber types were selected as reinforcement which are E-Glass and Aramid fibers. As matrix epoxy resin was used. Homogeneous and hybrid structures were manufactured. In hybrid structures configuration was arranged as E-Glass layers are at the front and Aramid layers are at the back. Two different hybrid composites were manufactured with 50:50 and 70:30 Aramid and E-Glass layers. The effect of volume fraction of fabric layers on ballistic properties was investigated. Since there is a linear relationship between V50 and thickness, composite structures were manufactured with two different thicknesses and by the equation derived V50 values for different thicknesses could be determined. Mechanical and ballistic tests were carried out in the study. Tensile, 3-Point bending and short beam strength tests were applied as mechanical tests and a V50 test was carried out as ballistic test. Composite structures were compared with each other based on test results. Consequently, it was found that hybridization method increased mechanical and ballistic properties. Mass efficiency of hybrid structures were found to be higher than 1 (E-Glass composite was used as reference). It was also found that presence of E-Glass layers assists aramid structures to experience more delamination during impact and therefore increased energy absorbing capability.Master Thesis The Effects of Light-Weight Interface Material on the Stress Wave Propagation in the Multilayered Composite Armor System(Izmir Institute of Technology, 2011) Tunusoğlu, Gözde; Taşdemirci, Alper; Taşdemirci, Alper; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe main purpose of the current study is to investigate the effect of interlayer material on the ballistic performance of composite armor and stress wave propagation both experimentally and numerically. Three different interlayer materials, EPDM rubber, Teflon and Aluminum metallic foam, were tried. Relatively large pieces of the ceramic around the impact axis in the rubber interlayer configuration were observed while the ceramic layer was efficiently fragmented in Aluminum foam and Teflon interlayer configurations. Accordingly, more significant amount of delamination in composite layer of without interlayer, larger and deeper delamination in EPDM rubber configurations was observed while fewer amounts were observed on Teflon and Aluminum foam configurations .Also, all interlayers caused reduction in the magnitude of the stress transmitted to the composite backing plate, particularly Aluminum foam. However, EPDM rubber did not cause delay in the initial stress build-up in the composite layer, whereas Teflon (~15 ms) and Aluminum foam (~25 ms) caused a significant delay. Also, as ceramic was efficiently fragmented in Teflon and Aluminum metallic foam interlayer configurations, greater amount of projectile kinetic energy was absorbed in this layer, as a consequence, the remaining energy which was transmitted to composite backing plate was decreased. At this point, the effectiveness of Aluminum foam and Teflon were validated with conducting ballistic tests and corresponding numerical simulations and impact chamber tests. After this validation, the ballistic performance of aforementioned materials was compared at equal areal densities. Finally, Aluminum foam was found to be more effective interlayers in reducing the stress values transmitted to the composite backing plate and reduction of the damage imparted to this layer.