Influence of core and matrix modifications on the mechanical characteristics of sandwich composites

Sandwich composites are increasingly being used for a variety of applications owing to excellent properties like high bending strength and stiffness, low strength-to-weight ratio and excellent damping and acoustic properties. However, there are certain issues faced while using sandwich structures for structural applications which includes debonding of face sheets from core, matrix cracking and core shear failure. In the current work, an effort is made to enhance the mechanical characteristics of sandwich composites by altering poly vinyl chloride (PVC) foam core and adding multi-walled carbon nanotubes (MWCNT) to epoxy resin used as the matrix. Four different configurations of sandwich laminates were fabricated using vacuum bagging process: (1) plain core and neat epoxy resin (2) core with blind holes and neat epoxy resin (3) core with blind holes and epoxy resin with MWCNT (4) core with through holes and epoxy resin with MWCNT. Flexural and compression tests were carried out on these sandwich specimens according to American Society for Testing Materials (ASTM) standards. Sandwich specimens with through holes in the core and resin mixed with MWCNT exhibited better mechanical characteristics compared to the other sandwich laminates. Type 4 sandwich specimens were able to withstand 12% and 16% more flexural and compressive loads respectively compared to conventional sandwich specimens.