Çeşitli mikro kanal kesit geometrilerine sahip karbon elyaf takviyeli kompozitlerin darbe ve eğilme davranışlarının belirlenmesi

In this thesis study, the effect of embedded microchannels serving functions such as thermal management, self-healing and damage detection in smart/multi-functional composite applications on the mechanical performance of carbon fiber reinforced polymer (CFRP) laminates has been investigated in terms of channel cross-section geometry. Reference test specimens without channels (NC) were compared with reference test specimens which have circular (CC), square (SC), hexagonal (HC), and star-shaped (StC) channels; behaviour under bending load was evaluated using a three-point bending test according to ASTM D790, while behaviour under impact load was evaluated using a 30 J low-velocity drop weight test according to ASTM D7136. In order to quantitatively relate geometry to the mechanical results, cross-sections of reference specimens were scanned using a coordinate measuring machine (CMM) and modelled in CAD software to calculate section properties. The results indicate that microchannel integration does not completely compromise performance under suitable production conditions; however, the damage initiation threshold and propagation characteristics change significantly as the cross-section becomes angled or complex. In terms of equivalent bending rigidity (SB), the highest increase compared to the NC (non-channelled) reference sample was observed in the circular-channelled (CC) reference sample (+68.1%). The absence of sharp corners in the circular cross-section limits stress concentrations, ensuring a more homogeneous load transfer and explaining the observed trend. In addition, circular geometry can offer advantages in terms of preserving fiber continuity, as it can cause lower local fiber deviation compared to sharp-edged channel geometries during manufacturing. While peak forces followed a similar pattern in impact tests, the absorbed energy was found to be lower in all channelled groups compared to NC (non-channelled test specimens). However, post-impact visual examinations have shown that the discontinuities created by micro-channels can divert the path of damage propagation, thereby limiting damage propagation in the thickness direction to a certain extent and contributing to the damage remaining more localised. Keywords: Smart composites, Embedded micro-channels, CFRP composites, Bending test, Impact test