The mechanical properties of sandwich structures based with composite column cores

Composite sandwich structures containing high-performance core materials based on vertical composite columns have been manufactured using a lost-mold technique. The structures were prepared by drilling holes at specific locations through a dissolvable mold block. Long carbon fiber strands were then inserted into each of the holes, ensuring that one continuous tow extended through all of the vertical elements within a given core structure. Two threading techniques were used to prepare the composite columns. One resulted in the horizontal fibers extending along the inner surfaces of the composite facings and the other involved weaving the fibers through the composite facing. Both methods offered the advantage that the fibers formed part of the upper and lower skins. Following infusion with epoxy resin, using the VARTM manufacturing procedure, individual specimens were removed from the blocks in preparation for subsequent compression testing. The results were compared with an FE model which showed good agreement in terms of predicting the modulus of elasticity and peak stress.