PhD Dissertation Defense:Yağız Özbek
INNOVATIVE MANUFACTURING FOR SANDWICH STRUCTURES: APPLICATION OF ATMOSPHERIC PLASMA ACTIVATION AND INCORPORATION OF RECYCLED THERMOPLASTIC COMPOSITE SKINS
Yağız Özbek
Manufacturing Engineering, PhD Dissertation, 2024
Thesis Jury
Assoc. Prof. Dr. Hatice Sinem ŞAŞ ÇAYCI (Thesis Advisor), Prof. Dr. Bahattin KOÇ, Assoc. Prof. Volkan ESKİZEYBEK, Assoc. Prof. Bekir BEDİZ, Asst. Prof. Cihan ÇİFTCİ
Date & Time: 17th December, 2024 – 15.30 PM
Place: FENS L067
Zoom link: https://sabanciuniv.zoom.us/j/6938110217?omn=99052655769
Keywords : Sandwich Structures, Atmospheric Plasma Activation (APA), Randomly Oriented Strand (ROS), CF/PEKK, Mechanical Performance.
Abstract
Advancing sandwich composite structures is crucial for overcoming performance, sustainability, and structural reliability challenges in the aerospace industry. This thesis explores the effect of composite surface treatment on the mechanical performance of secondary bonded sandwich structures. It also provides a comparative analysis of sandwich structures with traditional thermoset composite skins and recycled thermoplastic composites for aerospace secondary load-bearing applications. The research begins by examining the effect of atmospheric plasma activation (APA) treatment on the thermoset composite skins and its influence on the mechanical performance of sandwich structures. Once the behavior of the thermoset sandwich structure is understood, this analysis serves as a reference for evaluating the potential use of recycled thermoplastic skins in sandwich structures. Next, the thesis investigates the influence of strand size and morphology on the physical and mechanical properties of recycled randomly oriented strand (ROS) CF/PEKK composites. By comparing ROS composite panels made from long, short, and shredded strands, the study identifies the most suitable alternative to thermoset composite skins. Following the optimization of the manufacturing process for both the recycled ROS composite skins and the sandwich structure as a whole, the thesis conducts an in-depth analysis of the mechanical and thermomechanical behavior of sandwich structures incorporating recycled ROS composite skins. In conclusion, this thesis demonstrates that recycled ROS composites offer an environmentally friendly and cost-effective alternative to thermoset composite skins in sandwich structures for aerospace secondary load-bearing applications.