Effect of Cryogenic Environmental Condition upon Flexural Properties of Aluminum- Epoxy/ Basalt Fibers- Glass Fibers Laminates

In this study, effect of fiber arrangement and cryogenic cycles on the flexural behavior of fiber metal laminates (FMLs) were investigated. The FMLs were prepared from two aluminum 2024-T3 plates and basalt-glass fibers/epoxy composite in the central part of it. These composites were prepared in 5 different fiber arrangement by hand Lay-up technique. In order to enhancement of adhesion between aluminum and composite, aluminum surfaces were treated by electrochemical treatment (anodizing). Each cycle was carried out in 3.5 min between -100 and 25 °C. The laminates were cycled for 40 times and their flexural performance were studied before and after cryogenic cycle. In order to characterization of failure mechanism of specimens, scanning electron microscopy and optical microscopy were used. The highest and lowest flexural strength and modulus consequently belonged to the specimen with layers of basalt fibers (BFML) and the specimen consisted of glass fibers (GFML) because of weak properties of glass fibers in comparison to basalt fibers. After carrying out cryogenic cycles, BFML had the highest percentage of difference with respect to this specimen before carrying out the cryogenic cycle. These difference in flexural strength and modulus were 6% and 4.9% respectively. But in the case of GFML, difference percentage in flexural strength and modulus were 2.5% and 1.6% respectively that was the lowest percentage of difference after cycling. When the hybrid FMLs were carried out by cryogenic cycles, due to overcoming the pressure stress mechanism on delamination between composite components, results showed enhancement in flexural behavior.