LEE- Katı Cisimlerin Mekaniği-Yüksek Lisans

Bu koleksiyon için kalıcı URI

http://hdl.handle.net/11527/19330

Gözat

Sustainable Development Goal "Goal 7: Affordable and Clean Energy" ile LEE- Katı Cisimlerin Mekaniği-Yüksek Lisans'a göz atma
  • Öge
    Development of H-BN and CNT reinforced polymer composites for electronic warfare receivers and transmitters: Examination of thermal performance
    (Graduate School, 2023-06-21) Cengiz, Gürcan ; İrez, Burak Aleaddin ; 503201522 ; Solid Mechanics
    Electronic warfare (EW) is specified as military capabilities concerning electromagnetic spectrum (EM) manipulation to the greatest extent possible to achieve control over the spectrum and provide the capability of attacking an opponent or obstructing adversary attacks. EW provides the capability to counter hostile acts utilizing the electromagnetic spectrum throughout the conflict. Electronic warfare attempts to detect the presence of the adversary's electronic supports as part of combat capabilities, eliminate the efficacy of the adversary's electronic warfare supports, and prevent the destruction of friendly EW resources' effectiveness. The main subsystems of a typical radar system include a transmitter, an antenna system, a receiver, and signal-processing electronics. The transmitter is used to generate a high-powered RF signal with variable frequency. The antenna system radiates energy and collects reflected waves. The receiver detects signal return. Meanwhile, the signal-calculating electronics transcribe range, speed, and bearing target measurements. The reliable operations of electronic warfare systems rely profoundly on their electronic components and communication systems, which dissipate significant amounts of energy over their lifetime due to the Joule effect and must endure tensile and bending stresses. Effective thermal management is essential to remove this energy from the system. Tensile and flexural strength are also critical mechanical qualities. Typically, metallic alloys such as aluminium are used in the casings of these components due to their high thermal conductivity coefficients and excellent mechanical properties. However, the high density of such metals increases the system's overall weight. Therefore, the aerospace industry actively seeks lightweight polymer composites to reduce the weight of the casings. This thesis aims to create a high-performance composite material with improved thermal and mechanical properties for electronic warfare transmitter and receiver casings while lowering their overall weight. To accomplish this goal, multi-walled carbon nanotubes (MWCNTs), hexagonal boron nitride (h-BN), and thermoplastic vulcanizate (TPV) were integrated into a thermoplastic matrix composed of acrylonitrile butadiene styrene (ABS). Theoretical models and calculations, as well as material homogenization, were established in order to estimate tensile properties and thermal conductivity. Matrix and reinforcements were melt mixed using a twin screw extruder. The coupling agent maleated polyethylene (MAPE) was added in the twin-screw extrusion process to ensure the homogeneous mixing of the reinforcements and the matrix. For the experimental characterizations, specimens were manufactured using the injection molding process. Experimental characterizations such as FTIR spectrography analysis, SEM analysis of fracture surfaces, density analysis, tensile and flexural tests, impact tests, hardness tests, DSC analysis, and thermal diffusivity testing of the composite were conducted to assess its mechanical and thermal properties, as well as to explore the influence of the reinforcements on the composites' properties. The newly developed composites were evaluated and assessed for their usability as an alternative to aluminium in transmitter and receiver unit casings regarding critical qualities such as density, tensile strength, flexural strength, impact resistance, and thermal conductivity.
  • Öge
    Energy absorption and deformation mechanisms of triply periodic minimal cellular hybrid structures
    (Graduate School, 2022-02-11) Deniz, Alper ; Kırca, Mesut ; 503181519 ; Solid Mechanics
    One of the fields in which TMPS are aimed to be employed is energy absorption owing to their cellular topologies. As a result, studies show that some types are superior in acoustic and some other types have superior heat resistance. Some of the recent studies aim to create hybrid formulations in some ways like changing density gradient or function modifications etc. For instance, recent studies in tissue engineering aim to find hybrid designs which meet the requirements to use them as bones in medical applications. This study proposes by showing the energy absorptions with deformation mechanics of hybrid structures that obtained from common TMPS in order to guide the researches to choose which model in certain applications.This study aims to show a systematic design -including FE model- of hybrid structures and their energy absorption abilities with deformation mechanics comparison in purpose of finding the possibility to use hybrid models instead of basic functions in some areas including public and private safety issues.