It is generally accepted that mechanical properties of sandwich composite are affected by curing pressure variation. For the present study, the effects of curing pressure variation on the compressive properties of balsa wood sandwich composite were investigated. For this purpose, a compressive test was conducted using balsa wood and honeycomb core sandwich composite, applying 40 psi and 60 psi curing pressure conditions. The results showed that compressive load of balsa wood sandwich composite applying 60 psi curing pressure condition is higher than applying a 40-psi curing condition. This phenomenon is due to an increase in the adhesive strength of the balsa wood sandwich composite as the curing pressure increases, thereby improving the compressive strength. Deboning and local buckling were observed on fracture surfaces of all balsa wood sandwich composite, but only global buckling was observed at honeycomb core sandwich composite.

It is well-known that the mechanical properties of MMT (montmorillonite) nanocomposites are better than those of conventional composites. In this study, tensile tests were performed to determine the effect of silane modification of MMT and its weight ratio on the tensile properties of MMT/epoxy nanocomposites. It was found that the tensile strength and the elastic modulus of MMT/epoxy nanocomposites increased with increasing weight ratio of MMT. The elastic modulus of silane-modified MMT/epoxy nanocomposites was higher than that of untreated MMT/epoxy nanocomposites, irrespective of weight ratio.

It is generally accepted that fracture toughness of fiber-reinforced polymer composites is affected by strain rate in an atmospheric pressure condition. For a present study, the strain rate effect on the fracture toughness of fiber-reinforced laminated composites in the hydrostatic pressure condition was investigated. For this purpose, fracture tests have been conducted using graphite/epoxy laminated composites applying three steps of the strain rate at 270 MPa hydrostatic pressure condition. The strain rates applied were 0.05 %/sec, 0.25 %/sec, and 0.55 %/sec. Fracture toughness was determined from the work factor approach as a function of applied strain rate. The result showed that fracture toughness decreased as the strain rate increased. Specifically, the fracture toughness decreased 12% as the strain rate increased from 0.05 %/sec to 0.55 %/sec.