Recently, glass fiber reinforced polymer composites have been increasingly used in applications which are exposed to impact loads due to their high strength, low weight, and corrosion resistance properties. Therefore, the effect of curvature of composite laminate on their impact resistance is important. In this study, the mechanical properties of three curvature diameters and two stacking sequences, which have not been compared before, were examined and compared. The diameter of curved composites is 760 mm, 380 mm, and 304 mm and flat designated as A, B, C, and D, respectively. The fiber stacking orders are [0/0/-45/+45/90/90]S and [90/90/-45/+45/0/0]S designated as Type 1 and Type 2, respectively. The drop-weight impact tests were performed and failure modes of composites were examined. It was observed that the impact resistance decreases with the increase of curvature, where 760 mm diameter and Type 2 composites had the highest strength in all of the composites. In addition, delamination, fiber breakage, and matrix cracking failure modes were observed in the composites after impact. The reason why the strength decreases as the curvature of the composite increases is that the curved areas create an effect that increases the external force applied. The reason why Type 2 stacking order is more durable than Type 1 stacking order is that the 90° fiber direction in the bottom layer has a damping effect on the applied force. According to the results of this study, composite materials with larger diameter and stacking order starting with 0° provides more mechanical strength. [Formula: see text]

Purpose The purpose of this paper is to investigate and find out the surface and electrochemical behaviours of twin roll cast (TRC) 8006 aluminium alloy with different thicknesses due to the cold rolling rates after the TRC process. Design/methodology/approach The 8006 aluminium alloys are mostly used for the food packaging industry, as they are corrosion resistant, lightweight and shapable materials. The present work investigates the surface and corrosion behaviours of 8006 aluminium alloys at different thicknesses. TRC aluminium alloys were cold-rolled at two different reduction rates before investigation. X-ray diffraction (XRD) and energy dispersive spectroscopy (EDX) tests were used to examine the phase and elemental analyses. FE-SEM and 3D profilometry also used to observe surface morphology. Open circuit potential (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy tests (EIS) were carried out to find out corrosion behaviours. The results show that the more cold rolling reduction (CRR), the more corrosion rate and surface affection of the TRC 8006 aluminium alloys. Findings According to the electrochemical tests (OCP, potentiodynamic polarization test and EIS) and surface morphology results (such as SEM, 3D profilometry and XRD) the more the rolling rate the less the corrosion resistance. Originality/value First corrosion behaviour investigation of twin-rolled 8006 Al alloys using electrochemical techniques. First investigation of CRR effects on electrochemical corrosion behaviour of 8006 Al alloys with 3.5 wt.% NaCl solution using EIS. First investigation of 8006 Al alloys as a food packaging material with electrochemical ways.