Makina Mühendisliği

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http://hdl.handle.net/11527/25302

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Yazar "Irez, Alaeddin Burak" ile Makina Mühendisliği'a göz atma
  • Öge
    Development of sunflower husk reinforced polypropylene based sustainable composites: an experimental investigation of mechanical and thermal performance
    (Wiley, 2024) Irez, Alaeddin Burak ; orcid.org/0000-0001-7316-7694 ; Makina Mühendisliği
    Climate change, shrinking resources, and rising raw material costs have pushed the industry to create more sustainable, and lightweight materials. Natural fiber composites are materials of interest for replacing conventional materials such as steel. Sunflower husks (SH), among many other natural fibers, are readily accessible as agricultural waste and have advantageous properties. In this study, sunflower husks were mixed with polypropylene (PP) matrix using a twin-screw extruder, and then tests specimens for experimental characterizations were manufactured through injection molding. The tensile tests revealed that the inclusion of SH into PP decreased the load-bearing capacity of the composites by around 20% and increased their impact resistance by over 200%, while reducing the ductility by about eight times. Moreover, magnesium hydroxide (Mg(OH)2) was incorporated into the composites as a flame retardant, and it has improved the stiffness and impact resistance of the composites. Besides, incorporation of SH and Mg(OH)2 elevated significantly the glass transition temperature of the composites. The use of Mg(OH)2 delayed 60% the flame retention of the composites observed from UL-94 HB flammability testing. In summary, they could be suitable for components such as spare wheel wells, seat backs, trunk floor, the acoustic panel behind the door, and airbag housing.
  • Öge
    Inspection of microwave self-healing efficiency in carbon nanotube reinforced polymer composites for aerospace applications
    (Wiley, 2024) Irez, Alaeddin Burak ; orcid.org/0000-0001-7316-7694 ; Makina Mühendisliği
    The aerospace industry is evolving very rapidly every day, and due to the low operational and maintenance costs, unmanned aerial vehicles (UAVs) are utilized for many duties, including imaging, patrol, surveillance, and delivery. Flying platforms prioritize effective load-carrying capacity and light weight. To achieve this, lightweight materials with sufficient strength are utilized, and design optimizations are implemented. This study investigates material development for a UAV propeller, taking into account the possible consequences of a bird strike or hard landing such as micro damage occurrence. In this study, a twin-screw extruder was used to produce hybrid composites by blending a thermoplastic, polyamide-6 (PA6) with olefin block copolymers (OBC) and carbon nanotubes (CNT). After manufacturing test specimens by injection molding, tensile and Charpy impact tests were performed. OBC increased the elongation capacity and impact resistance of the PA6 through maleic anhydride (MAH) grafting while reducing the tensile strength. CNT incorporation compensated for this drop, but it rendered the composites more brittle. More importantly, due to the CNT's microwave (MW) absorption capacity, the hybrid composites have gained self-healing properties. Extended MW exposure time and high MW powers may cause localized burning of the material, resulting in a decrease in its self-healing efficiency. Following the failure of the examined composites, SEM microscopy revealed various toughening mechanisms in the composites. The use of a modified Halpin-Tsai model to estimate the elastic characteristics of CNT-reinforced composites revealed promising results, with minimal discrepancies when compared to experimental data. Highlights CNTs were found efficient for the self-healing behavior which is critical for improving the lifetime and planning maintenance for UAV propellers. CNT content, MW power & exposure time all impact the self-healing efficiency. Extended MW exposure time and high MW powers can cause localized burning of the material, resulting in a decrease in its self-healing efficiency. CNTs created bridge effects, ultimately leading to an enhancement in the strength of the composites. The use of a modified Halpin-Tsai model yielded good accuracy with experimental data.
  • Öge
    The microstructural evolution of material extrusion based additive manufacturing of polyetheretherketone under different printing conditions and application in a spinal implant
    (Wiley, 2024) Irez, Alaeddin Burak ; Dogru, Alperen ; orcid.org/0000-0001-7316-7694 ; orcid.org/0000-0003-3730-3761 ; Makina Mühendisliği
    With the advances in additive manufacturing, polyetheretherketone (PEEK), a biocompatible polymer, can be used in biomedical applications such as spinal implants. This paper aims to investigate the evolution of the microstructure of PEEK parts manufactured by material extrusion (MEX)-based additive manufacturing with different printing parameters. The effect of layer thickness (LT) and nozzle diameter on mechanical properties was investigated using tensile, Charpy impact, and short beam strength (SBS) tests. Two different LTs, 0.1 and 0.2 mm, and two different nozzle diameters, 0.6 and 0.8 mm, were used as printing parameters. By increasing the LT, tensile strength dropped by around 24%, and impact strength by almost 55%. Moreover, altering the LT resulted in a 15% decrease in interlaminar shear strength (ILSS) from the SBS test. In addition, increasing the nozzle diameter also led to a significant reduction in all of the results as tensile strength, Charpy impact strength, and ILSS. The results were also consolidated by scanning electron microscopy. The main findings were that increasing LT leads to an increase in microstructural defects that act as stress concentrators. Following the tests, response surface methodology (RSM) was used to determine optimal printing parameters. In the end, using the optimum printing parameters from the RSM study, a structural analysis of a MEX-printed spinal implant was conducted through finite element method, considering the loading cases mimicking daily human body motions. Highlights As layer thickness increased, tensile and impact strength dropped. Tensile and impact strength dropped truly with increasing nozzle diameter. SEM revealed that increasing layer thickness causes more microstructural flaws. FEM analysis showed that PEEK-based implant provides structural integrity.
  • Öge
    Transformation of waste carbon fiber prepreg into sustainable composites: application in the automotive industry components
    (Wiley, 2024) Irez, Alaeddin Burak ; Yakar, Hasan ; orcid.org/0000-0001-7316-7694 ; Makina Mühendisliği
    Carbon fiber (CF) prepregs are employed in the manufacture of many different aeronautical structural and non-structural components. Following the cure of the prepregs in molds, trimming is generally used to give the final shape to the components. Considering the aircraft's vast surface area and the use of multiple prepreg layers in each component, an extensive amount of carbon fiber prepreg is discarded. The unique characteristics of carbon fibers render this CF waste highly valuable and requires its efficient recycling. Cured waste CF prepregs were milled and processed in this research to produce chopped carbon fibers for use in the novel composite development. The matrix material used in the composites was selected as recycled polypropylene sourced from old surgical masks, which highlighted the sustainability of the developed composites. To enhance the quality of the fiber-matrix interface and improve the impact resistance of the composites an anhydride-grafted polyethylene (Fusabond) was employed in small quantities. From mechanical characterizations, synergistic effects of the fillers were observed. Besides, compositions containing CF and Fusabond are found more impact resistant than neat matrix. In addition, the use of carbon fibers increased fracture toughness of the matrix through various mechanisms including fiber bridging, fiber pullout, and matrix plastic deformation identified by scanning electron microscopy fractography. Thermomechanical characterizations using dynamic mechanical analysis revealed that carbon fiber raises the neat matrix's glass transition temperature. The developed materials are intended to be employed in the automotive industry to produce inner fender liners, with an optimal composition determined by an optimization research. Highlights Carbon fiber (CF) derived from aerospace fresh scraps significantly improved the mechanical properties of the polymer matrix. Anhydride-grafted polyethylene incorporation remarkably enhanced the impact resistance of the polymer. CF demonstrated a bridge effect and improved the fracture toughness of the composites. The use of recycled CF presents encouraging prospects in the automotive industry for the production of inner fender liners.
  • Öge
    Tribologically enhanced self-healing hybrid laminates for wind turbine applications
    (Wiley, 2024) Hasırcı, Kemal ; Ergene, Berkay ; Irez, Alaeddin Burak ; orcid.org/0009-0004-8370-515X ; orcid.org/0000-0001-6145-1970 ; orcid.org/0000-0001-7316-7694 ; Mechanical Engineering
    Wind turbines are subjected to extreme weather and load conditions; hence, high strength and impact resistance are required. Furthermore, wind turbine blades can be subjected to impact loads such as bird strikes, resulting in the formation of microcracks. Self-healing capsules can be used to mend turbine blades for microscale damage. The incorporation of self-healing capsules may cause a decrease in the mechanical characteristics of the composites prior to impact resistance, which can be compensated for with efficient fillers such as silicon carbide whiskers (SiCw). Thus, a novel hybrid composite structure is examined with the advantage of using a self-healing mechanism and SiCw reinforcement. Tensile, tribological, and Charpy impact tests were performed to characterize the mechanical and tribological properties, which were supported with microscopic observations. Multiple experimental characterizations were performed to investigate the impact, and the ultimate tensile strength (UTS) and energy absorption capacity of the structure were shown to increase by 32% and 45%, respectively, with the addition of SiCw. The presence of self-healing agents provides a 5% rise in UTS after enough time for healing following the collision. The structure's tribological performance is improved by 10% in wear resistance and 20% in friction coefficient. Highlights Hybrid laminated composite structure with silicon carbide whisker and self-healing capsules. Tensile and Charpy impact tests conducted with microscopic observations Increased ultimate tensile strength and energy absorption capacity by 32% and 45%. Tribological improvement by 10% in wear resistance and 20% in friction coefficient.