Effect of nano-silica on fatigue behavior of glass fiber-reinforced epoxy composite laminates: A Weibull distribution approach

The aim of this study is to assess the impact of nano-silica in glass fiber-reinforced epoxy composite (GFEC) subjected to static and fatigue loading. Laminates were prepared in compression molding machine followed by the tensile test and tension-tension fatigue testing at five different stress levels (from 50% to 90% of ultimate tensile strength). The addition of 3 wt% of nano-silica with epoxy improved the tensile and fatigue strength as compared to neat GFEC. Scanning electron microscope (SEM) images of the fractured specimen showed the damage pattern which indicates that neat GFEC laminate exhibited damage patterns characterized by fiber breakage and matrix cracking. On the other hand, the modified GFEC with nano-silica showed damage patterns including fiber pullout accompanied by fiber breakage and matrix cracking. During cyclic loading, the stress-strain hysteresis loop shows a reduced slope, indicating a decrease in the dynamic modulus of the specimen. This reduction in slope signifies a loss of stiffness during cyclic loading, particularly at high-stress levels. The highest dynamic modulus at high-stress levels indicates a rapid progression of severe damage and a shorter fatigue life. On the other hand, at low-stress levels, the lower magnitude of dynamic modulus suggests a moderate damage progression and a longer fatigue life.