Hamed Khosravi - Faculty of Materials Science and Engineering, K. N. Toosi University of Technology, Tehran, Iran. Department of Materials Engineering, Faculty of Engineering, University of Sistan and Baluchestan, Zahedan,Iran
Reza Eslami-Farsani - Faculty of Materials Science and Engineering, K. N. Toosi University of Technology, Tehran, Iran.

In the present study, multiscale nanosilica/E-glass/epoxy anisogrid composite panels were investigated for flexural properties as a function of nanosilica loading in the matrix (0, 1, 3 and 5 wt. %). The surface of the silica nanoparticles was firstly modified with 3-glycidoxypropyltrimethoxysilane. The Fourier transform infrared spectroscopy revealed that the organic functional groups of the silane were successfully chemically grafted on the surface of the nanoparticles. It was illustrated that flexural properties of thecomposite panel loaded from the skin side can be significantly enhanced by incorporating silica nanoparticles. From the 3-point flexural test, it was found that using of 3 wt. % nanosilica was the most effective in increasing the load bearing capacity and energy absorption value, while the specimen containing 5 wt. % nanosilica demonstrated the highest flexural stiffness. The results obtained for the anisogrid panels loaded from the skin side showed that these structures displayed excellent damage resistance which is represented by their energy absorption capability. Moreover, a significant portion of energy absorbed after the primary failure at the peak load. Finally, the results correlated well with the observation of field emission scanning electron microscopy micrographs where the nanocomposite panels exhibited higher degree of fiber-matrix interfacial strength and also enhanced matrix characteristics, imparted by the incorporation of surface modified silica nanoparticles.

Anisogrid-stiffened composite structure, Multiscale composite, Silica nanoparticle, Surface modification, 3-point bending response, Energy absorption