Optimization of low-velocity impact behavior of FML structures at different environmental temperatures using Taguchi method and grey relational analysis

Carbon fiber-reinforced Aluminum Laminate(CARALL) materials are a relatively new generation of Fibre Metal Laminate(FML) materials that have attracted interest due to their superior properties. This study investigates the low-velocity impact behavior of CARALL structures at different environmental temperatures(-40°C, 23°C and 80°C). Two different groups of CARALL composite structures with varying fiber orientations were produced by hot pressing in a 3/2 arrangement: C1(Al/0°90°/Al/90°0°/Al) and C2(Al/0°0°/Al/0°0°/Al/0°0°/Al). Low-velocity impact tests were conducted at 23J, 33J, and 48J energy levels using a Ø20 mm spherical impactor tip. The area of damage was detected by ultrasonic C-Scan. In addition, analysis of variance(ANOVA) was applied to reveal the influential parameters and their effect levels. After conducting experiments using the Taguchi L ₁₈ test set, it was observed that the C2-coded specimen yielded better results in terms of maximum peak load, maximum displacement, and damage area. While the decrease in temperature increased the damage and maximum peak load, the increase in temperature did not cause a significant change in the maximum peak load. The primary damage mechanisms observed in damage investigations were matrix cracks and delamination between composite layers. Although delamination is present between the Al/CFRP layer, it is not significant. This result highlights the success and importance of the Phospho-Sulphuric Anodizing(PSA) pre-surface treatment applied to the aluminum plates. In all experiments, the most effective parameter was the impact energy. The optimal experimental conditions (23°C temperature and 23J impact energy with the C1-coded sample) were determined using grey relational analysis based on principal component analysis.