Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
Browse
2 results
Search Results
Master Thesis Numerical and Experimental Investigation of Thermal Performance of Graphene Reinforced Aluminium(01. Izmir Institute of Technology, 2020) Yılmaz, Ahmet Berk; Toprak, Kasım; Kandemir, SinanGraphene is a material with superior properties such as high thermal conductivity and mechanical strength. These exceptional properties make graphene a good candidate for being used as a reinforcement agent in other materials. Aluminium is a widely used material in industry for thermal applications for being cheap, lightweight and having high thermal conductivity. In the literature, there are many examples of graphene reinforced aluminium production. Also, the effects of graphene on thermal conductivity and mechanical properties of aluminium are also investigated experimentally. However, there are limited molecular dynamics studies for graphene-aluminium composites. In this work, aluminium, graphene and graphene coated aluminium are modeled and simulated with non-equilibrium molecular dynamics method. Length, width, height, temperature dependence of thermal conductivity of these models are investigated. In addition, effects of graphene layer number, defect size and defect locations are also reported. Additionally, an experimental setup is designed and produced for a comparative study. Thermal performances of aluminium alloy and graphene nanoplatelet reinforced aluminium are investigated with a convection heat transfer test.Master Thesis The Deformation Behavior of a Multi-Layered Aluminum Corrugated Structure at Increasing Impact Velocities(Izmir Institute of Technology, 2017) Sarıkaya, Mustafa Kemal; Güden, Mustafa; Taşdemirci, AlperThe compression impact deformation of a layered 1050 H14 aluminum corrugated sandwich structure was determined both experimentally and numerically under low, intermediate and high velocities to investigate the validity of the perfect and imperfect models. Three-dimensional finite element models of the tested specimens were developed using the LS-DYNA. At increasing velocities from quasi-static velocity to 200 m s-1, the tested corrugated structures showed three distinct deformation modes: between 0.0048 and 22 m s-1 the deformation was quasi-static homogenous mode; between 22 and 60 m s-1 a transition mode and above 90 m s-1 a shock mode. These observations were also confirmed by the camera records and model layer strain profiles. The imperfect models predicted the deformation behavior in homogeneous and transition modes, while the imperfect and perfect models both well predicted the shock mode. Layer strain profiles showed that as the velocity increased, the crushed layer densification strains increased. The numerical models and experiments of direct impact tests showed that distal end crushing stress increased with increasing velocity. The increase of the stress within the homogeneous and transient mode velocities was ascribed to the micro-inertia effect and the tested corrugated structure showed a Type II behavior. The rigid perfectly plastic locking (r-p-p-l) model prediction using quasi-static plateau stress and densification strain and quasi-static plateau stress and numerically determined densification strain at that specific velocity resulted higher velocities and full densification, while the r-p-p-l model based on varying plateau stress and densification strain well predicted in the shock mode.