Experimental Study on the Bending Behavior of 3D Woven Glass Fiber Sandwich Composite Panels

Three-dimensional integrated woven sandwich composites (IWSCs) consist of two woven fabric faces and an integrated hollow core. The two parallel faces are bonded using pile yarns which keep a defined distance between the top and bottom. In order to characterize the mechanical properties, three-point bending test was performed on the IWSC sandwich composites. The results showed that by increasing the thickness of the composite and therefore increasing the moment of inertia, the flexural strength of the specimens increases. The average amount of bending force increase by increasing the thickness for different samples is equal to 80% to 120%. Also, by increasing the pile density, the flexural strength in hybrid and non-hybrid specimens increases. Therefore, the maximum flexural load is obtained from the composites with the highest thickness and pile density. On the other hand, due to the different arrangement of piles in the warp and weft directions, IWSC panels show different behavior in these two directions. The values of flexural strength in the direction of the warp are higher than the direction of the weft due to the higher density of pile yarns and therefore the higher shear strength of the structure in this direction. In different composites, this difference is 75% to 90%. The fracture properties of the composite under bending load show that due to the high strength and modulus of the face-sheets compared to the core section, the piles are more deformed and damaged and the face-sheets are not noticeably damaged. Also, the damage to the top face sheets of samples tested in the weft direction is greater than that of warp direction.