Hygrothermal degradation of mechanical properties of nanoclay based stainless steel and glass fibre-epoxy laminate

Fibre metal laminates (FML's) are the multilayer composite laminates of metallic sheets and fibre reinforced plastic (FRP) composites. The stacking sequence of metallic sheets and FRP prepregs in FML's vary as per the type of fibre metal laminate and its application. FML's are the most suitable materials for shipbuilding, aerospace and aeronautical structural use due to better mechanical properties over traditional materials. In the present research, the mechanical properties of nanoclay based stainless steel and glass fibre-epoxy laminate (SS FML) have been investigated. Hygrothermal conditioning of specimens was performed in two aqueous environments at 40 °C and 70 °C for three months. After hygrothermal conditioning, tensile, flexural, compression and Izod impact tests were performed as per ASTM standards. It is concluded that the nanoclay addition in the epoxy matrix of SS FML improves its mechanical properties drastically. It is due to the fact that the nanoclay in the epoxy matrix improves the interfacial bonding between the composite layers. It is observed that the mechanical properties were reduced more in distilled water due to the salts available in seawater that reduces the moisture absorption in epoxy matrix of SS FML. It is also noticed that the temperature has the considerable effect on the degradation of mechanical properties. Higher temperature of water softens the epoxy, results in highest degradation in distilled water at 70°C.