İlgi alanları

• MakaleYayıncıda açık erişim2026Scopus SJRQ1/r/bayburt/12680
  Surface modification and tribological performance of AISI 4140 steel via shot peening and plasma nitriding: A systematic evaluation of conventional, repeated and severe plastic deformation

  Erdoğan, Ömer; Kovacı, Halim

  Despite its widespread industrial use, AISI 4140 steel exhibits limited resistance to wear and surface damage. This study investigates the effects of vibratory shot peening and plasma nitriding processes, applied individually and in combination, on the tribological performance of AISI 4140 steel. Shot peening was performed under conventional (CSP), re-shot peening (RSP) and severe shot peening (SSP) conditions, while plasma nitriding was carried out at temperatures of 460 °C and 535 °C. The severe plastic deformation created by shot peening increased dislocation density, significantly improving nitrogen diffusion during plasma nitriding. The SSP condition resulted in the highest surface hardness, increasing from 248 HV0.1 to 533 HV0.1, while the combined SSP and plasma nitriding treatment produced a maximum hardness of 920 HV0.1. In dry wear tests, the combined application of shot peening and plasma nitriding significantly reduced the wear rate, achieving a reduction of approximately 94% compared to the untreated sample. In saltwater environments, wear behaviour was controlled by the continuity of the nitride layer and the diffusion depth, resulting in an 82% reduction in wear rate for the SSP and plasma nitriding condition. Overall, it has been observed that applying vibratory shot peening prior to plasma nitriding significantly improves the tribological performance of AISI 4140 steel.

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• MakaleAçık Erişim2023Scopus SJRQ2/r/bayburt/12918
  Dynamic response of polypropylene honeycomb/polystyrene foam core sandwich composite panels: Experimental and numerical analysis

  Caliskan, Umut; Demirbas, Munise Didem; Erdogan, Omer

  In this study, dynamically loaded sandwich panels with two different core materials and face sheets made of aluminum alloys (6061-T6) were investigated experimentally and numerically under low-velocity impact. Polypropylene, PP (C3H6)n honeycomb and extruded polystyrene foam, XPS (C8H8)n were preferred as core material. By using the contact force and kinetic energy changes, which were the impact test results of the sandwich panels, the contact and impact resistance was examined. As a result of the tests, damaged regions and permanent central displacement were determined and energy absorption capabilities were demonstrated for two different structures. The results obtained were compared with the results obtained by the open finite element method. In this study, it was shown that the face-sheet thickness of sandwich panels was an important parameter affecting the impact behavior. The behavior of the core material when the face-sheet loses its rigidity was investigated and it was found that polystyrene foam was more effective in preventing impact damage. However, it was found that using the PP honeycomb or XPS was affected the impact behavior in different points.

  AtıfScopus10·WoS10·OpenAlex12

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