Veysel Erturun

Purpose: This study aims to homogeneously mix Al, Zn, Cu, and Si metal powders with graphene nanoplatet and SİC ceramic powder reinforcements at various times and different Zn ratios using a high-energy ball milling device (Spex-type Retsch MM 400 model mixer). Design/methodology/approach: X-ray diffraction analysis (XRD) was used to investigate the effects of different Zn ratios and alloying times on the alloying process. The XRD data were used to calculate the crystal size using the Scherrer and Williamson-Hall equations. The alloyed powders were sintered and turned into billets. Then, images were taken from the polished surfaces using scanning electron microscopy. In addition, Vickers microhardness measurements of these billets were also examined. Findings: The Vickers microhardness test results showed a general trend of increased hardness with prolonged alloying times and elevated Zn content. The increase in composite stiffness can be attributed to two main factors. First, the high concentration of hard ceramic particles in the softer aluminum matrix contributes to this increase. Second, the formation of a robust interface between the aluminum matrix and the ceramic particles also increases the stiffness. This interface ensures efficient load transfer and increases the overall stiffness of the composite. The EDX analysis results also support the XRD findings. Originality/value: A high-strength aluminum alloy composite material has been produced and characterized for aircraft fuselage structures.

In this study, self-piercing riveting (SPR) connection, which is one of the joining techniques of aluminum alloys, is investigated. SPR is a cold mechanical joining process used to join two or more sheets of material by pushing the rivet that pierces the upper sheet under the guidance of a suitable mold and then locking it to the lower sheet. The SPR process was carried out with the split Hopkinson pressure par test system. The bar inside the cylinder, accelerated by pressure, performs the riveting process by hitting the surface of the mold developed for SPR. In this study, different numbers of slots were opened on the rivet tail, and the process was carried out using SPRs at different deformation rates. A powerful tomography scanner device designed for 3D metrology was used to visualise the SPR joining mechanisms without cutting. Tensile-shear tests were applied to the samples made with rivets with different numbers of slots and different pressures, and cross-tension tests were also applied to the samples prepared with rivets with different numbers of slots. The opened slots caused a decrease in the maximum strength of the samples. It was understood that the appropriate riveting pressure could change the connection strength by approximately 50%. In general, the force values decreased as the number of slots increased.

In this study, fretting wear in riveted lap joints of aluminium alloy plates was investigated. For the fretting test, 6061-T6 aluminium alloy plates, which are widely used in aircraft construction, and blind rivets were used. Experiments were carried out using a computer controlled Instron testing machine. Fretting surface roughness, microhardness was investigated by metallographic techniques and scanning electron microscopy.Tensile load cycles in the riveted lap joint were found to cause damage to all surfaces. Two contact surfaces where friction occurs were investigated. The contact surface of the lower plate with the upper plate, and the contact surface of the lower plate with the rivet head. As load and cycles increased, fretting scars and surface roughness increased.Consequently, it has been determined that fretting damages occur between the contact surface of the plates and between the plate and the rivet contact surface.